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Milliohm meters and component testers

Posted: Jan 09 2018 1:52pm
by ElectricGod
Some time back on my Power Velocity controller thread I stated that I was seeing inconsistent results in AOT290 mosfets. People criticized me and basically said I didn't know what I was talking about. I attempted to get people to refute my tests with testing on their part and none of the critics would in any way present actual test results.

In the process of that discussion, I bought 3 devices. An inexpensive component tester that measures Rds, a 2 wire milli ohm meter and a 4 wire milli ohm meter. I'll state right up front that of course the 4 wire meter is going to do the best job of measuring very low resistances. That was never in question for me despite the many critics claiming I thought otherwise. I just wanted to prove if the 2 wire meter could do the job or not.

So then here's my results...

This is my 2 most recent component testers and a bunch of components that I had that were unknown. They both cost less than $30 and do a great job of identifying loads of 3 legged or 2 legged parts. I highly recommend getting one if you want to quickly determine if your part works or have no idea what something is and want to determine quickly what some component is. I like the tester on the left better than the one on the right. It has far more functionality and the screen is easier to read. The right unit however is capable of measuring Rds...down to about 5 milli ohms. This is not useful for measuring Rds in mosfets used in controllers. Either meter will tell you what kind of component you have and lots of other specs on that part. I use these testers when ever I get a new batch of mosfets. In seconds I know which mosfets are matched and which ones are not. I also find that commonly mosfets are out of spec. Both of these testers on the same component are within 1-2% accuracy of each other.

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I haven't gotten around to further mosfet tests yet, but several critics refused to accept that I could test new mosfets on my component testers and see results that were well outside of specs. I pointed out that I was testing on my component testers and that after 3 of these testers, they were quite consistent with their test results despite being 3 different designs and made in 2015, 2016 and 2017. None of that mattered. I "had" to be doing something wrong, frying them with static...whatever, but the parts were sacred and holy and always 100% in spec. LOL! OK...believe what you like. I've tested mosfets so I'm not confused on this subject.

If you want to test components to see generally if they work or not or to determine what it is, get a Chinese component tester. They work great for most 2 or 3 legged electronic part. Some exceptions should be noted. Quite a few 3 legged parts are actually an integrated circuit and NOT just a single component inside. Voltage regulators and halls are great examples of this. It is not uncommon for these testers to NOT be able to identify them since they are multiple components integrated together into a 3 legged package. Don't assume that because your part is displayed as Unknown or bad that it is bad. Go look up it's data sheet to be sure it's not a 3 legged IC. Things like mosfets, resistors, caps, transistors, diodes, LED's, inductors should all read correctly. If any of them come back as unknown or bad, then that's an actual bad part.

This is a mosfet I tested...looks good!

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I bought a $40 2 wire milli ohm meter. I wanted to see if it would do the job of measuring down to 1 milli ohm or not. It's spec's say it should...so why not? The meter I purchased is really for testing capacitor resistance, but I already knew it would measure the resistance of anything and it does. Of course the critics leapt on the meter like it was a plague to be extinguished. LOL! I knew it wasn't going to do as well as a 4 wire meter, but that wasn't the point. Was it good enough to measure mosfet Rds or a shunt? I have to say that NO it's not, but if all you need is 10 milli ohm resolution then it's good enough for you. The original meter came with cheap alligator clips that would not consistently "grab" a component so they didn't measure low resistances consistently. I replaced the factory alligators with Kelvin clips and then connected both jaws together with some solder braid. The meter is much more consistent now, but it still doesn't reliably measure down into the sub 10 milli ohm range.

This is the meter testing a .005 ohm shunt. As you can see, the factory leads measure it as .012 ohms...just about 250% too high. LOL! If I jiggle the leads, the meter will sometimes actually measure .005 ohms, but most of the time it would display something much higher like this.

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The kelvin clips arrived a few days ago so I upgraded the meter leads and now I don't have to wiggle and jiggle to get consistent readings. Of course it still doesn't do sub 10 milli ohms very well, but it can. What do you want for a $40 2 wire meter?

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I paid about $100 for this 4 wire resistance meter. They get lots more expensive than this! All it does is measure very low resistances. It too uses Kelvin clips, but each side of the jaws is a separate test lead. Testing a precision .005 ohm shunt gets me pretty close to what the part should be. No surprises there.

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Why would someone want a meter that can only measure very low resistances and what is a milli ohm? A typical DMM measures down to about 1 ohm. That's enough resolution for checking your car speakers or for general continuity testing. What do you do when you want to measure lower resistances? Lets say you want to check some switch or relay contacts and you are concerned that they might be scorched. The $40 meter will test that. If you get anything above 100 milli ohms, those contacts are probably damaged. So then what is a milli ohm. Milli indicates 1 thousand or in this context 1/1000. So imagine your car speakers are 3 ohms each and you wanted measure the resistance of the speaker cable. Are they really "low ohm" cables? The $40 meter will tell you that close enough that it won't matter.

What if I want to test the resistance of a mosfet or a shunt? Now we are getting down into the very low milli ohm range. Modern mosfets such as the IRF4110, AOT290 and so on are used in motor controllers and BMS and are designed to have almost no resistance from source to drain (Rds). Achieving ever lower resistances across the switched junctions in a mosfet is something every mosfet manufacturer is seeking. For measuring this low of a resistance, you really need a 4 wire milli ohm meter. The 2 wire meters just can't do the job reliably. My tests show that's the case and I was already suspicious it was true, but hey test and now I know for sure. The next question is why do you care about the drain to source junction resistance? Resistance is loss and loss usually means heat in mosfets. The mosfets in your controller or BMS can only handle so much heat and then they die. Quite often they get too hot while still operating well under their current handling limits. Using mosfets that can handle more heat and also have very little Rds means they can run much closer to their current limits for more time than a mosfet that has a much higher Rds and less heat handling. Let's look at the the AOT290 vs the IRF4110. Both have similar Rds at 3.5 and 3.7 milli ohms, but the AOT290 can handle 500 watts of heat while the IRF4110 can handle 370 watts. The AOT290 can run hotter for longer than the IRF4110. Now lets talk about the AOT290 vs an IRF4115. The IRF4115 has 9.3 mill ohms Rds and 380 watts of heat dissipation. This is 2.6X more resistance than the AOT290. Resistance=loss=heat. The IRF4115 running at the same amperage and voltage as the AOT290 will get 2.6X hotter and also can't handle as much heat as the venerable AOT290. So low Rds keeps your mosfets running cool which means they can run harder and longer. The lower the junction resistance just means your controller won't overheat as easily as it would with higher Rds mosfets...and that is good for you!

So then why not just get low Rds mosfets and plug them into your controller. Great idea! Do it. But, I want to know if they are actually within manufacturer specs or not. That is where the component tester and 4 wire meter comes into play. Now I can measure all the mosfets specs and Rds for myself and then pick the mosfets that most closely match up. OR!!! I can buy loads of a specific mosfet and then find the ones with the lowest Rds and use them in my controller. Remember... resistance=loss=heat.

Mosfet testing

Posted: Jan 09 2018 3:08pm
by ElectricGod
I'm moving this over here and that helps keep the Power Velocity controller thread cleaner and on topic.

Supposedly A $30 component tester can't test a mosfet and get real results. Supposedly only the manufacturer of that part can test accurately and you can't. LOL...OK...believe what ever you want, but I know better. I have purchased several pieces of test equipment for this test. I'm going to test a bunch of mosfets and let the chips fall as they may.

I am testing 10 new of each mosfet: All mosfets are purchased from digikey, mouser or arrow except the ebay IRF4110's. Values in parenthesis are for identifying each mosfet of each type. They are in order of cost where number one is the cheapest mosfet.

If you know of another mosfet that has a low Rds, low on time, 100 volt and high current, high wattage, please post them. I'm willing to test other mosfets. If your suggestion is less than 375 watts, I'm going to ignore it if it doesn't also have a less than 3 milli ohm Rds.

1. Chinese IRF4110 purchased on ebay (C1 to C10)
2. IRF4110 (I1 to I10)
3. AOT290 (A1 to A10)
4. IXFP180N10T2 (X1 to X10)
5. CSD19536KCS (S1 to S10)

The tests consist of several things.
1. Put each mosfet labeled 1 to 10 in 2 component testers, record it's measured specs.
2. Set my bench PSU to Vt, put a .3 ohm resistance in series with the mosfet source and 15 volts on the drain. Measure the voltage drop across the resistor. Do I get 250uA across the resistor? If this matches what the component testers measure, that's proof the testers work as expected.
3. Set my PSU to Vgs(th) min/max and test Rds. This is just for curiosity. Do all mosfets of the same kind turn on the same?
4. Set the PSU to 10 volts at the mosfet gate and measure Rds.

A note about Vgs(th)...
I have seen this value vary widely in AOT290's. In my testing with component testers, this value can be way over specs. In testing the AOT290, I have seen a few mosfets at the minimum value of 2.9 volts, quite a few at or near the typical spec of 3.5 volts and many at or above the maximum of 4.1 volts. I've been told by the critics how this is not possible, but my testing shows what it shows.

For anyone who cares, here's a great PDF on mosfet testing.
https://www.vishay.com/docs/90715/an957.pdf

A few specs from the spec sheets. Sometimes they don't list all the values so this is what I have to work with.
IRF4110:
Rds: typical=3.7 milli ohms, max=4.5 milli ohms
Vgs(th): minimum=2.0v, maximum=4.0v

AOT290:
Rds: typical=2.5 milli ohms, max=3.2 milli ohms
Vgs(th): minimum=2.9v, typical=3.5v, maximum=4.1v

IXFP180N10T2:
Rds: max=6 milli ohms
Vgs(th): minimum=2.0v, maximum=4.0v

The results will be tabulated and presented here. As posted many times before, the results will be the results!

MINI BUCK converter and XM-L2's

Posted: Jan 14 2018 4:01am
by ElectricGod
More LED work done...

I got these little adjustable BUCK boards on ebay for 50 cents each. They work perfectly for driving XM-L2's. I'll be adding them to the XM-L2 lights soon. They take up to 24 volts in and convert it down to as low as 1 volt.

https://www.ebay.com/itm/10pcs-Mini360- ... 2749.l2649

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This XM-L2 is driving from 3.5 volts. It's running on the 6S pack it's sitting on with the BUCK dropping that to 3.5 volts.

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Handlebar Switch Clusters

Posted: Jan 26 2018 1:32am
by ElectricGod
I don't know about anyone else out there, but invariably I have more lights and accessories than what a single switch cluster will handle. My throttle will have a switch on it. The left side of my handlebars commonly have 2 sets of clusters becasue one isn't enough. I came across a couple of interesting products on ebay that finally address my switch issues.

This is commonly how my left side handle bar looks. One cluster is never enough. None of these directional switches are very clicky and it's easy to miss the off position.

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The above switches are the sort of cluster that I typically find and they are fine for headlights horn and directionals. They are never particularly tactiile for directionals. I always have at least 2 more sets of lights and commonly there's something else too.

This is a really nice cluster and the shell is metal, not plastic like so many others. The directional switch is super clicky which makes finding the off position easy and tactile so that I don't have to look down to find it. The toggle is for the head lights. If it was replaced with a 3 way switch, it could do off, low and high. This is probably the best 3 switch cluster I've ever found. At less than $6, that's a deal!

https://www.ebay.com/itm/7-8-22mm-Alumi ... 2749.l2649

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This is an all plastic 5 switch cluster I found. It's probably going to serve most folks well enough who need more than 3 switches. The bottom completely comes off which makes removing it from your handle bars easy since you don't need to slide it off the end of the bar to remove it. At $8 it's still pretty cheap. If you want a single left side switch cluster, then you will want to remove one of the switches and replace it with an on-off-on switch. It also has 2 momentary switches. Most people really only need one momentary switch for their horn. Moving one of the locking switches in place of the second momentary switch and then filling the empty hole with a 3 way switch would make this usable for most people who need a couple more switches and want a single all in one solution.

https://www.ebay.com/itm/Motorcycle-7-8 ... 2749.l2649

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I found this 7 switch cluster. I can't imagine needing more than this! It only has 2 locking switches and the rest are momentary. I had to buy more locking switches and replaced all of them except the one in the horn position and of course I added a 3 way toggle switch for directionals. The toggle is reasonably clicky. It has a metal shell and the bottom is held on by 2 M6 screws. There's 2 switches on the underside. It's fairly well constructed. AT $17 it's a bit expensive and especially since I have to replace all but 1 of the momentary switches. I think after I was done modding it, It cost me about $24. However, now it does everything I want.

https://www.ebay.com/itm/1x-7-8-Motorcy ... 2749.l2649

I added a JST connector so I could completely disconnect the bottom from the top. 5 locking switches is quite a lot and I don't think I need more than that ever. All switches have a single wire in common except for the 3 way switch.

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More LED stuff

Posted: Jan 31 2018 1:41am
by ElectricGod
Not really EV related, but a fun LED side project never the less. I'd like to see one of those expensive key chain lights be any brighter than this!

I bought 2 rechargeable LED keychain lights. They come with a chinese XP-L2 that had a strong blue hue to it...about 6K. They were decently bright, but I knew that I had real CREE XP-L2 LED's which were going to get put in these tiny lights. I reflowed a single LED so I could compare before and after results.

https://www.ebay.com/itm/Mini-LED-Brigh ... 2749.l2649

This is how they came to me from China. The black light is all aluminum with an aluminum reflector except the LED carrier which is brass. The other one is all stainless with an aluminum reflector and brass LED carrier. They include an internal micro USB port for charging the battery. It contains a tiny lithium cell.

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Once I had it apart and removed the Chinese LED, I compared a real CREE XP-L2 with the one in the light. It's obvious that the Chinese LED is NOT on the same par as the real part.

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Once I had one of the CREE LED's flowed onto the carrier, I took this picture. The real CREE LED is significantly brighter. For the comparison, I made sure both batteries were fully charged to be sure the brightness test was fair. The real LED's look downright yellow next to the 6K chinese LED. The real XP-L2 are 4K LED's. There's no doubt that this LED swap was well worth it. It looks like it's 3X brighter at least.

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I've had the beat up red light for a long time. I upgraded the LED in it some time ago with a much larger one that tripled it's brightness. Despite it having a really cheap LED in it, it's nearly as bright as these new lights before the XP-L2 swap out.

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This is one of the upgraded lights next to the beat up red light. Definitely much brighter.

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Quadlock adapter

Posted: Jul 25 2018 10:24pm
by ElectricGod
I like quadlock products. They hold really well. BUT they make mounts for a limited selection of phones. Most people are relegated to either buying the narrow band of supported phones or using the universal mounting kit. All of my phones fit into that category. That means attaching a quadlock wart to the back of the phone if I want to use it on my EV's. Personally I think it sucks as it makes the phone nearly twice as thick and it can't sit flat anymore. When I got a new phone a few weeks ago, I was NOT going to put another wart on it!

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I have lots of neo magnets so I used some to make a magnetic mount possible. Now the phone doesn't need a Quadlock wart on it. I found these stick on magnet plates for phones on amazon. I paid $5 for 10 of them. They stick to any flat and clean surface. That old quadlock wart is getting pulled off my old phone! BTW...once you stick a quadlock to something, good luck getting it pulled off! That glue is really good stuff.

This is the back of the phone now. I can't tell it's there since the phone still lays perfectly flat.

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I bought another quadlock universal mount. These things are NOT cheap at $15 each for a piece of plastic!

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I used another of the stick-on steel plates and super glued 8 neo's to it and then trimmed off the extra plate to make this.

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I then peelled of the backing on the quadlock adapter and off the back of the steel plate and stuck them together to make this. I may add some electrical tape on top of the magnets so the surface is less slick and can't scratch anything.

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On the back of my phone. 100% removable and attachable to anything else with a steel plate on it. It holds my phone quite well and I will never need to buy another quadlock universal adapter wart ever again.

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Re: Random tools and EV related projects

Posted: Aug 30 2018 6:25pm
by ElectricGod
That magnetic quadlock adapter has worked super well. My phone might as well be glued down!

Re: Random tools and EV related projects

Posted: Jan 10 2019 2:05pm
by ElectricGod
The magnetic quadlock mount worked out really well. I have 2 now. One is in my car all the time and the other gets swapped to whatever EV I am using at the moment.

I have 5 smart phones I use for various things. They all have a steel plate on them now.

XHP70.2 LED mod

Posted: Jan 16 2019 12:14pm
by ElectricGod
I bought a few of these lights on aliexpress. The hosts are well made. Solid aluminum, glass lense and aluminum reflector. Even the chinesium XHP LED in them is pretty good. These lights are all around pretty decent and well worth the money. The only plastic part is the gromet that seals around the wires as they exit the light and the spacer that isolates the LED from the reflector.

This is an ebay auction for them. I got them for $15 each including shipping on aliexpress.

https://www.ebay.com/itm/LED-Motorcycle ... :rk:1:pf:0

A pal in the UK wanted me to mod one with a legit CREE XHP70.2. I added an internal 1/8" thick aluminum disk. There's a narrow channel milled right under the LED for the wires to exit. This would have created a hot spot directly under the LED. The added aluminum disk fixes this issue. Getting the wires through that channel is a little harder now, but still doable. I used teflon coated wire since they would be so close to the underside of the LED. THe exit via that dark circle in the aluminum.

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The XHP70.2 gets secured to the center of the aluminum disk with thermal glue.

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If Chinese manufacturers are going to skimp, it's usually in things that "look" like they are quality and are not. These lights have an aluminum reflector and a glass lense.

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This specific Castle BEC is too weak for the XHP70, but you get the idea. I have 15 amp BECs coming soon for them. These hosts have very little internal space. Ther eis no room to place the BEC inside and the legit XHP70.2 runs too hot for the BEC inside these small hosts. It would get cooked. I have to water proof the BEC and mount it elsewhere. Castle Creation BECs are really nice. They can be set to a wide voltage range and their current ratings are usually pretty accurate.

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To test the light once it was all built, I used a 5S, 12,000mah LIPO pack. This is the current at the pack...about 3 amps.

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This is the nature of DC-DC converters of all kinds. input and output voltages and currents do not have to match, just the over all wattage. 5S is approximately 20.5 volts. At 3 amps that's 61.5 watts. I have the BEC set to 6.7 volts and I'm reading about 8 amps going into the LED or 53.6 watts. The 10 amp BEC does get pretty warm so I'm betting the lost wattage is heat in the BEC or 7.9 watts...which is a lot IMHO.

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This is a smaller host of somewhat similar quality. However as is typical, China decided you don't need an aluminum reflector or a glass lense. Otherwise it is the exact same quality as the bigger version. This host is too small to run an XHP LED, but it's perfect for an over driven XML. The black light at 53.6 watts gets pretty warm just sitting on my desk running for 30 minutes. The silver one with an XHP in it would get far hotter than is acceptable for this monster LED.

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I made a couple of videos last night comparing the XHP70.2 with the factory light and with a 100 watt equivalent LED bulb.

https://www.youtube.com/watch?v=zzqlr2G ... m6nfZ&t=0s

https://www.youtube.com/watch?v=WpW6J4- ... m6nfZ&t=0s

XHP70.2 LED light

Posted: Jan 23 2019 11:08pm
by ElectricGod
I completed this light today and then did some testing.

I originally bought the wrong Castle Creations BEC and of course it was too weak for the XHP70.2 without lots of heatsinking. The 14S, 15 amp BEC 2.0 is is the right BEC for the job. Never the less a little beefing up is always a good thing. After making sure it works that is!

There's a really small piece of aluminum on top of these mosfets and other components that acts as a "heatsink". It really is not enough AND I wanted to waterproof the board. I coated the entire top side in conformal.

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The bottom gets a thick coating of conformal too. I add a bit of heat shrink around the base of the wires so they can't flex independently and break off the board as easily. Each wire also gets heat shrink around it so that can't shrink back or have an insulation failure at the board. They are just nylon insulated. The big wires at the right are silicon insulated. They will take lots of heat without issues.

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I made this U-shaped section of aluminum that is just slightly taller than the thickness of the board components that wraps around the board. The mosfet side gets thermal glue on it and is then pressed down to the aluminum. There should be enough thermal glue in there to fill every gap in the top of the board so that heat can transfer to the aluminum as directly as possible. I clamp the board down until the thermal glue sets up. This makes the mosfets have nearly direct contact to the aluminum. The tweezers are wrapped in tape to squeeze down the board to the aluminum until the glue sets up. While I'm at it, I filled in around most of the board. The next day, I filled in the gaps and around where the tweezers were so that thermal glue transfers heat to the aluminum form every surface possible. This also ensures there are no voids or places that water can get into the BEC. It will probably be mounted near the light and where weather can get at it.

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I really shortened the programming cable and then buried it in heat shrink so that water can't get in anywhere except at the pins. This was probably not necessary, but oh well. The whole thing went inside an 18650 tube and shrunk together. You'll notice the CC bEC label on top. That was the aluminum heat sink that was originally on the BEC.

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The bottom of the BEC with a little thermal paste or gap filler can be zip tied down to something metal to act as a bigger heat sink. For my testing I used a 3x3 heatsink.

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I ran the light with no air flow for 15 minutes and temps peaked at 217F which is pretty hot, but it all worked OK. No Chinese LED would tolerate that without burning out! The BEC got to 120F on the heat sink. I turned on the fan and measured the air flow with my anemometer. The fan is about 8" from the light. The meter said at the fan I was seeing about 10 mph air flow and in front of the light 6 mph air. That's pretty slow! I was soon seeing the light cool off. Within about 3 minutes it was down to 140F on my laser temp meter. I left the light running with the fan for 30 minutes and temps dropped to 100F at the light and 92F on the BEC. This is what I expected and is "normal" conditions the light will work in. Most folks won't be moving quite that slow so most of the time the light wont get overly warm.

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Deans connectors are fairly ideal for this sort of thing. I put them between the BEC and the light and for feeding 12v into the BEC. I don't really care if there is water incursion at these connectors. What will it damage?

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Re: XHP70.2 LED light

Posted: Jan 25 2019 3:14pm
by MJSfoto1956
ElectricGod wrote:
Jan 23 2019 11:08pm
I completed this light today and then did some testing.
A+ work there.

Mosfet switches

Posted: Jan 31 2019 12:57am
by ElectricGod
The XB-502 has dual XHP70.2 head lights. The headlight switch was never intended to handle that much current. It's just a matter of time before the contacts are gone. I needed a better way to turn on the power for them. AKA...mosfet switches. I really only need 2 mosfets, but got several of these 4 mosfet boards from ebay so I guess more is better. I can always double up the mosfets for more current.

The mosfets on the boards are good for 100v and they are average mosfets, but they are good enough for this use. If I really cared, I'd swap them out for a top end mosfet, but they wont see enough current to matter. The right board is how they arrived to me. I replaced the screw terminals. They were not very good. The control connectors don't lock in place without special connectors and I have lots of JST stuff so I swapped them out too. I pulled the mosfets, straightened the legs, tested each one and then soldered them down into the board as far as they would go. This will maximize the current handling of the mosfets and allows me to add a heat sink. There's an LM723 voltage regulator on the board and they are good to 40 volts. These boards despite the mosfets are NOT good to 100 volts. They are useful for 5-40 volts.

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The original screw terminals on the left pinch the wires under the screws and can break them. They are capable of 2-3 amps. The screw terminals on the right, use little boxes that are drawn up around the wire by a screw. The screw never touches the wires and never causes any pinching or breakage. Also they can handle a lot more current...more like 10 amps. I use these screw terminals a lot. they are pretty darn good and not very costly.

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The final product. The heat sink is covered in a couple layers of kapton tape. The mosfets have thermal glue behind them and are secured by an insulated screw. I also coated all the electronics in conformal. This will handle quite a lot of current per channel now and water can't hurt anything.

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solder and soldering 101 part 1

Posted: Aug 27 2019 12:43am
by ElectricGod
I posted all of this elsewhere in a build thread, but this is my general EV related thread so I'm reposting it here.

People think that soldering is easy. It is if you do a few things correctly. I've been soldering for 40 years and so I'm pretty good at it and I'm particular that my solder joints look a certain way. I often times find solder work that is really pathetic. A lot of stuff like switch clusters out of China, wiring and things hand soldered in China are horribly done. Of course they use cheap Chinese solder which I'll talk about later.

Here's a good video on soldering
https://www.youtube.com/watch?v=SFKYUi3p8zY

I have to add a few items to the video since it deals with small connections only.

1. Go to the local hardware store and get a tin of solder flux. I solder a lot...like multiple times a week and a tin of flux will last me a year or more doing just EV related soldering. It is commonly used for soldering copper pipe together, but it is your best friend when soldering wires and electronics. It is very common that a wire won't tin properly with just the flux in the solder. Dip it in the flux and then it soaks up solder like nobodies business! The tiny bit of flux inside the solder just can't keep up with all the air gaps in between wire strands. I dip any wire end in solder flux before tinning it. The tinning process goes so much better if I do. A solder pad that won't flow solder very well probably just needs a tiny dab of flux added to it. I dip switch legs, wire ends, parts legs, just about anything in flux so that I get optimal solder flow.

2. If you have a bullet connector or large hunk of copper or whatever it is, put a little solder flux on the area that is supposed to get soldered to. Then heat up that area and the solder flows much better and bonds better. If the solder makes beads on the surface, there's very likely a need for some flux to get through the oxide layer and to help solder flow. For small components being soldered to a board, I probably won't add flux to that, but just about everything else...definitely yes.

3. Everybody wastes solder. Everybody can scrounge solder from old circuit boards or other sources. It doesn't matter the source, it's just solder and you want a little blob of it sitting around. I have no idea what that solder my blob is actually made of. It's all kinds of solder from all kinds of places. I solder a lot so I have the blob I use which is about 1/2" across and then a much larger blob that is waiting to be eventually used up. A little flux on many small drops will clean up the tiny bits of solder and cause them to flow together into a large blob. Whenever you need to tin the end of a wire, dip the bare wire end in the flux, melt the solder blob and immerse the end of the wire in the solder blob. Instant tinning! If the wire won't take solder very well, dip it in the flux again and then into the liquid solder blob again. I re-use solder in this manner constantly. The same solder blob can be remelted a thousand times and be just fine. If it gets grunge in it, put a little flux on the blob and remelt it...clean solder! The above video showed cleaning your solder tip and then retinning it with fresh solder. Why waste new solder when you have a solder blob readily available? Just dip the soldering iron tip in the melted solder blob and it's tinned again.

4. When your solder cools, it should be smooth and gloosy. It should flow around the connection smoothly and evenly. Clumpy solder or solder with chunks in it or a joint that doesn't flow very well was either made too cool, needs more flux or there's oxidation that the flux can't overcome. I tend to solder hotter than most people do. I use a Hakko 936 soldering station that has variable tip temperatures. I solder too hot becasue I want excellent solder flow. It also means I need to be quick so I don't damage heat sensitive electronics and plastics.

Notice the large solder traces on the bottom of this motor controller. They are lumpy and dull.

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This is the exact same solder traces. Now they are lots smoother and more shiny. I did 2 things. The first was my soldering iron was hot enough to properly melt the solder. The second was I added a little flux to them to clean up the solder once I did get it to properly melt.

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5. In the above picture, notice how the solder is not silvery and glossy despite reflowing it with sufficient heat. it has a dull shine, but not a glossy shine to it. This is due to the metals used in the solder. The big thing these days is to use lead free solder. That's fine, but it means that the metals used need to simulate the melting and hardening points for lead and tin and the flowing and bonding characteristics of those metals. Cheap solder is made of garbage ingredients. Good lead free solder has a high silver content...like 1-2%. The silver makes the solder look glossy, but it also is an excellent bonding agent. Cheap solder can look dull becasue the metals used do not heat and cool at the same rates. Lead and tin harden pretty close to identically so they make glossy connections that do not have tiny fractures. Cheap solder will have metals that cool at radically different rates or harden at differing temperatures so the solder will be dull and rough. Looking at it at 500X you will see tiny cracks, fissures and crystal like structures in the solder. This is BAD. As metals cool, they contract. As a metal transitions from liquid to solid it contracts a lot. If the contraction ratios of all the metals and the temperatures they harden at are not similar enough the solder connection will be full of tiny cracks and fissures. Just avoid cheap solder. Chinese solder can be the worst!

This is horrible solder. I bought a couple spools of it and it's just crap. I won't be buying Chinese solder again! Who knows what is really in this supposedly 60/40 Chinese solder! There's virtually no chance it is what the label says. If I run out of good solder blobs, I'll melt down some of this and mix it with good solder for the purpose of tinning wire ends and my soldering iron tip. Otherwise, it is virtually useless in my opinion.

https://www.ebay.com/itm/0-8mm-400g-60- ... SwB-1YyKM5

It's a little more money, but this is going to be good solder that cools shiny, flows well and makes a strong joint. Of course it's made by Kester and they have been selling solder to professionals for many years. A couple more dollars for good solder is worth it IMHO. When Kester lists metal content, those are real values and you can expect good results.

https://www.ebay.com/itm/Kester-1lb-Sol ... 0020!US!-1

6. Soldering irons...just avoid the $10 soldering iron from walmart or radio shack!!! Seriously! Don't EVER buy them. They are not worth the electrical chord they come with. Don't be uber cheap. Get something decent. As a minimum, you want interchangeable tips. Avoid soldering guns. They are basicly terrible for soldering just about everything. I had one and threw it away. I didn't use it for anything.

I've had several of this style of Weller soldering iron since the 80's and they still work great. The tip is replaceable and you will want to get a few different tips depending on what you are soldering. I think I paid about $35 for them too! I eventually wore out the original tips and bought replacements. They don't see use anymore, but they are a good soldering irons.

https://www.ebay.com/itm/WELLER-WP25-So ... 0020!US!-1

Ignore any soldering iron that is chordless or that runs on a fuel. You want one that plugs in to a power source such as the wall or a controller. You want a grounded soldering iron. That means 3 prongs in the plug. I had one of those instant on soldering irons a long time ago. They have the tiny gap in the tip that you bridge with the wire or solder and then it heats up. I paid like $40 for it and used it for a couple of weeks trying to get the technique down and to see if it was worth having. In the end, I gave it to a friend and went back to real soldering irons. Trust me on this, instant on is crap. Just get a soldering iron that needs to stay hot like the above Weller or the below Weller soldering station.

If you solder a lot like I do, then it may be compelling to get a solder station. My Hakko 936 was new in 2009. It has replaced all of my other soldering irons. With interchangeable tips and a really powerful temperature range, I can solder just about anything no matter how large or small it is. I bet it's still working in 10 years.

This is a Weller soldering station. I bet it's pretty good. I've never used it, but this is not going to be disappointing.

https://www.ebay.com/itm/Weller-WE1010N ... Sw-JJaaLUS

The Hakko 936 is no longer made, but you can buy them used for around $60. Don't be fooled by the Chinese knock-offs that look like the legit product, but cost $40. A legit 936 costs about $140 new.



Any soldering iron IMHO needs several features.

1. Interchangeable tips in several differnt types...one tip does NOT do everything. This is flat out a minimum requirement in my opinion. Sometimes you need to transfer loads of heat. That's a big, wide tip. Sometimes you need to solder to a tiny area. That's a very pointed tip. For most general soldering a tip that is 1/16" wide and partly flattened works pretty well. I vary mostly between 3 tips depending on what I'm doing. I have one that's a 3/16" wide flattened tip for soldering big stuff like large wires, bullet connectors and reflowing large solder traces. I have a tip with a 1/16" wide flattened end for general soldering. I have a tip that's elongated completely round and good for getting into tight spaces like soldering to the pins in an IP68 connector. I have lots of other tips too, bu they rarely get used.

2. Variable temperature with lots of wattage is the bomb. 70 watts is pretty nice! It means that I can turn the heat down to solder something delicate and tiny or turn it way up to solder a block of copper to a 6 awg wire. My Hakko gets hot enough to melt those aluminum solder rods. I can do limited aluminum soldering with it!

3. The grip needs to stay cool. If the handle is getting uncomfortably hot, then that means you won't be holding it for very long or doing a decent solder job. I solder for hours at a time and leave my iron on for hours at a time. The grip warms up to maybe 90F.

4. A slender soldering pencil is easy to manage and doesn't hinder your soldering work. A soldering iron that is bulky (solder gun) will just impair your work. I talked about my Weller soldering iron. I actually have 3 or 4 of them in different temperature ranges.. They are much larger soldering irons than my Hakko pencil. If I ever replace my Hakko for some reason, it will have to be with something that is slender, light weight and comfy to hold.

solder and soldering 101 part 2

Posted: Aug 27 2019 12:44am
by ElectricGod
In a previous post I talked about good and bad solder.

I pulled out my 500X USB microscope, melted a blob of crappy Jinhu solder and a blob of MG Chemicals solder and a blob of the random junk salvaged solder I use for tinning wire ends. The Jinhu solder smells like hair spray right in your face when the flux burns off. The MG doesn't really smell like anything. I have to say that the hair spray smell is quite annoying! Notice that the Jinhu solder says 60/40 on the lable. This indicates that it is supposed to be 60% tin and 40% lead. The MG solder also says it's 60/40. I believe that label, but the Jinhu crap is definitely NOT 60/40!

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I photographed these 3 blobs individually under the microscope so that I could not get them confused with each other. Left to right...MG, random and Jinhu. They are all going to have some amount of flux residue on them. The amount is not relevant to how good the solder is going to bond. These are fresh blobs of MG and Jinhu and who knows about the random stuff, but I did clean it up with a little flux.

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This is the MG Chemical solder. Kester 60/40 solder is going to look just like this. It melts right, solidifies right and bonds well...like good solder ought to do. It's glossy and smooth looking even at 200X. At 500X you can finally see that it some amount of surface roughness.

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Jinhu solder at 200X is obviously crap. It also does not flow into a joint particularly well and when it cools, it is brittle compared to the MG solder. The metals in the solder do not cool and solidify at the same rates. As a result the metals that cool quicker leave openings that the other metals get squeezed into since they are still liquid. The bumpy texture is the result. At 500X you can see the rough outer surface with glossy inner surfaces. The metal hardening rates are separated even more with the metal with the lowest melting point filling in the fissures or low spots which are now shiny.

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The random blob is who knows what kind of metals and it has been used over and over again. What specific metals are in here is anybodies guess! At 200X it looks far better than the Jinhu solder does. At 500X you get to see how much the salvaged solder is lacking. You can see open cracks and fissures in the surface of the solder. It's fine for tinning a wire end or solder tip, but not very good for serious solder work.

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A bit more solder testing...

I cut off the end of this junk circuit board and then cleaned off the green solder resist with a diamond emory board and then scrubbed it vigorously with a pencil eraser. When clean, I labeled the sections 1 (MG), 2 (random) and 3 (Junhu). Then I put down 3 small spots of flux so that I could put my 3 solder blobs on them.

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I heated the solder blobs just long enough to make it turn to liquid and then removed the soldering iron. The copper underneath did not have time to get hot enough to flow the solder. All close up shots are at 100X.

The MG solder blob. Still the best looking of the 3 blobs and it's even flowing a little bit.

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The random solder blob. No noticeable flowing yet.

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The Jinhu solder blob. No noticeable flowing yet.

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Fresh MG solder with no added flux soldered to the copper. I gave the copper time to heat up so that the solder could properly bond to the copper. You can see that the edges of the solder are well bonded to the copper and it's almost like they are feathered together.

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Fresh Jinhu solder with no added flux soldered to the copper. I gave the copper time to heat up so that the solder could properly bond to the copper. The Jinhu stands vertically away from the copper and does not flow into it very well.

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The final results.

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One more test on the solder blobs. This time I'm holding the soldering iron tip in each spot for 10 seconds to get everything hot. I don't add any flux or more solder. All I'm doing is heating the old spot for 10 seconds. This is more than enough time to heat the copper underneath and get the solder to flow onto it. 100X magnification. After I took these shots, I added a dab of flux to each of the 3 blobs and then reheated them for another 10 seconds each. Since the copper and solder was already pretty clean and fresh, this did not change the flow results at all.

MG solder...the edges of the solder are flowing onto the copper very nicely.

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Random solder...the edges of the solder are flowing onto the copper about as well as the MG solder. Despite this being who knows what solder mixed together, it's far better than the Jinhu crap!

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Jinhu solder...the solder stands vertical from the copper and does not flow hardly at all. This is not dramatically different from just barely melting the solder glob. As I've said all along...poor grade solder! Even the blob is very domed. It's like the blob does not want to adhere to the copper. If the solder is still fairly hot and mostly solidified, you can break it off the copper. It just does NOT bond very well.

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solder and soldering 101 part 3

Posted: Aug 27 2019 12:55am
by ElectricGod
I thought a smal ladd-on to this subject was in order. I scrounged some solder off a dead BMS that just came straight from China. I knew it was crap, but this is really bad. I've seen this before.

Here's the cold lump of solder. Notice how the desk top has no gunk on it. Notice how crusty looking the solder is. No gloss, dull and cracked looking. It;s actually full of pores and small cracks. NOT solid metal through and through.

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Notice the grunge and slime left behind the solder as it is rolled off a little. ALL of this goop was inside the solder in it's many little pores and cracks. How can that be good? All I did was melt the solder blob. Buy good solder...stuff with real lead and tin...made by weller or kester or other name brands. Avoid the chinese crap like I presented above.

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breakers and contactors

Posted: Nov 19 2019 10:17pm
by ElectricGod
It has been a good while since I posted in this thread.

I recently came across a DC breaker good up to 200 amps and 72v.
DC breakers have a voltage rating becasue they have a tuned circuit inside for breaking the arc without scorching the contacts.
I've run DC breakers at well over their voltage rating and they do OK.

This product line has a reset button so opening the breaker manually is pretty easy and they are water proof.

https://www.amazon.com/gp/product/B07DJ ... UTF8&psc=1

I want a contactor 99% of the time, but it would be nice if an overload occurred to have a breaker too. DC breakers that can handle a decent amount of voltage and current are far and few between. Most are good up to 48v and used for solar stuff. More voltage is pretty rare. I also wanted something inexpensive. All the the other higher voltage DC breakers that handle decent current cost well over $100. So here I am with a 72v, 200 amp breaker that cost me $26. I can live with that!

I want the breaker external so I can hit the reset button like I do when I turn off a contactor to cut battery power. All EV's need maintenance or upgrades so a convenient way to cut battery power is essential. This breaker thanks to the button can be my contactor and breaker all in one.

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There is a tiny issue, the battery posts are on top of the breaker. They are press fit stainless steel studs that enter through the bottom. The bottom of the studs are flared so you can't drive them out the top. You need to make the hole under each stud large enough to accommodate the flared section so you can drive them out the bottom. After that, flip over the studs and drive them back in the top. Now the studs come out the bottom so you can attach wires inside your battery box. This doesn't leave a lot of plastic around the stud.

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I assumed that the studs may not be long enough to pass through something before they are available for bolting down wire lugs. Stud length and much diminished plastic convinced me to do it this way instead.

There are 2 6mm holes in the plastic directly under the studs. I used these holes to get me dead center in the studs and then drilled them out to 7mm. Once I had drilled deep enough to be in the threaded section, I stopped drilling. I used my band saw to cut off the hollow stud and then tapped the hole for M8. A bit of clean up of any jaggy edges and they look like this.

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This stainless M8 bolt is just for example. I'll get some longer brass ones later.

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This threaded section is where the battery wires bolt down.

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The 2 open holes mount the breaker to the battery box wall. The 2 studs will need some clearance around then if they pass through metal.

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With the M8 bolts removed layout on something is pretty easy for the 4 bolt holes. A little silicon or closed foam around the holes will keep out water.

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Re: Random tools and EV related projects

Posted: Nov 19 2019 10:56pm
by amberwolf
I looked at some specs on this type of breaker on one of the various listings for them, and there's a bit of info that's not clear:
eNDURANCE FOR e9_123:500 cycles, 200% 14Vdc
Any idea what they might mean by the "e9_123:500" cycles part?

Also, there's this review
https://www.amazon.com/gp/customer-revi ... B07DJ5ZSTW
indicating at least some versions may have contact issues?

Looks like this version
https://www.amazon.com/STETION-Circuit- ... D32KT0JVNV

is available up to 250A for $19.99, but it only says up to 48v.

Re: Random tools and EV related projects

Posted: Nov 19 2019 11:10pm
by ElectricGod
amberwolf wrote:
Nov 19 2019 10:56pm
I looked at some specs on this type of breaker on one of the various listings for them, and there's a bit of info that's not clear:
eNDURANCE FOR e9_123:500 cycles, 200% 14Vdc
Any idea what they might mean by the "e9_123:500" cycles part?

Also, there's this review
https://www.amazon.com/gp/customer-revi ... B07DJ5ZSTW
indicating at least some versions may have contact issues?

Looks like this version
https://www.amazon.com/STETION-Circuit- ... D32KT0JVNV

is available up to 250A for $19.99, but it only says up to 48v.
E9: Type of breaker. Surface mounted with 2 outward facing terminals in these dimensions.
_123: No idea...I googled for "e9_123" and the only reference I found was the breaker you list above.
500 cycles: Make break cycles under load makes sense to me.
200% 14Vdc: Less arcing at lower voltage so you get 1000 make break cycles.

I saw lots of 48 volt breakers. I never run at 48v. The lowest I go is 66v and I build a lot more often at 82v. That's why I specifically went for the one rated for 72v.

These breakers are made in China. Contact issues...no surprises there. I've been using Chinese contactors for years and they do OK. Now that you mention this, I think I'll drill out the 4 rivets holding it together and take a look inside! I can easily put it back together with M3 screws and nuts.

Re: Random tools and EV related projects

Posted: Nov 19 2019 11:37pm
by amberwolf
I'm mostly curious because I'm interested in a waterproof solution for the trike that I can leave exposed underneath the cargo bed, easy to reach without looking, knowing where it is, and trip or reset as needed, in place of the regular flip-type breaker I have inside the cargo/seatbox, and potentially replacing the big battery cutoff switch.

breakers and contactors

Posted: Nov 20 2019 12:02am
by ElectricGod
Taking the 4 rivets out was easy. All I had to do was drill off the flared end and they pushed right out.

I'll just say up front, these E9 breakers are actually breakers capable of breaking a DC arc. They use a mechanical arc breaker inside. You can use them for DC at any voltage. Mechanical arc breakers don't really have a voltage range. It's electronic DC arc breakers that have a tuned voltage range. Feel free to use it at 12v or 150v DC. There is no difference.

The bottom of the breaker is all inside molded plastic. It won't ever let in water. The lid is sealed down with a silicon gasket that also seals around the post for the activation lever.

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OK...where is that arc breaker? I've seen it in DC breakers before. The silver arm lifts out easily. This is what the yellow button pushes on to open the breaker contacts. The small spring releases the yellow lever.

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Taken all apart...where the heck is that arc breaker?! I bet all the rest of the E9 breakers are just like it inside.

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There is a bit of scoring on the contacts already. I guess it actually got tested under load. I've seen 50 amp contacts on name brand relays and these are about 3X larger. I'd say they are 200 amp contacts once closed. Make/break...more like 100 amps. 500 make/break cycles under 200 amp load...highly unlikely....maybe 5 or 10 times before the contacts are getting rough. However for use as a contactor 99% of the time, I think the contacts will be OK. I use a precharge anyway so arcing across the contacts will be rare. For the occasional overload, I think it's OK. I did get the 200 amp version and intend to use it at more like 100 amps so for me, this will be OK.

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This little square of bi-metal is where all the magic happens. It's cold now so it forces the contact on it into the other contact in the base of the breaker. Heat it up and the bi-metal flexes the other way and breaks the connection. I guess the copper strip across the top is the current path and it heats up the bi-metal under it. I have to wonder if the lower amperage versions use a thinner copper strip and the same bi-metal square. I wonder if they all use the same contacts too?

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Will the DC arc breaker please stand up?! I still haven't found it!

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Here it is on the post that goes to the lever. When the breaker pops open, the spring that attaches to this post swings the lever out and this plastic paddle swings in between the contacts. It's a mechanical arc breaker.

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This position the contacts are closed.

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This position the contacts are open and the arc is broken.

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breakers and contactors

Posted: Nov 20 2019 1:28am
by ElectricGod
Putting the breaker back together, I realized that the bi-metal dome was not originally centered in the space. It's hard to see it in the picture, but it's all the way over to one side of the space. This means the contacts are not centered over each other. The retaining nut tightens and carries the bi-metal dome along with it until the dome touches the side wall. Nothing keeps the dome centered except that nut. The nut has nothing on it's threads to make it stay tight so I added a bit of blue locktite so it can't migrate loose over time. I wonder if this nut coming loose is the root cause for failure in these breakers or if the contacts are. Notice the clear bumper on top of the nut. It protects the silicon seal from abrading on its sharp edges.

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When I put the dome back in place, I put a screw driver in the gap so that the nut could not migrate the dome over to the side. I also tightened the nut more than it was from the factory. I really think that nut comes loose after a while for some breakers.

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While i was in there, I used some 2000 grit sand paper to polish off the tiny bit of scoring on the contacts.

4 M3 screws and nuts replace the rivets.

Motor winding spool holder

Posted: Nov 22 2019 10:18pm
by ElectricGod
Several years ago I tried to rewind a motor. I had a single spool of 20 awg wire and nothing to mount it on. I drove a screw into my bench top just so I could pull wire. It took forever to get 10 strands x 3 phases off a single spool. Later, I got some 14 awg on a single spool...same thing...nothing to mount it on. This is for the birds!

I went out into the garage, found a random stick of wood that fit inside the spool, found a couple of old pieces of pine board and some scrap plywood. In about 10 minutes, I threw together a spool holder. It worked, but it sucked and still only held 1 spool.

Time passed and I got tired of tolerating that slapped together spool holder. I needed a spool holder worth having. I made this. All the strands come out holes in the piece of wood and tie off to several screws so they stay put when in storage. It's about a year sine I first made it and I've made a few changes to it, but nothing major. It will hold 2 10 pound spools in the upper back or 4 5 pound spools...all side by side. Plus it will hold all the smaller spools down below. Or like you see here, 16 1 pound spools top and bottom. There is a third hole about center in the sides for really large spools. I have room in the lower back to add another set of holes for more 1 pound spools, but I have yet to need more than this. Right now...the upper right 4 spools are 24 awg and the rest are 28 awg. Being able to controllably pull so many strands at once is big time saver. They never snag or tangle on anything which is great. From the right side are 2 aluminum rods with knobs on them for holding the spools. The weight of the spools keeps the rods from sliding back out the right side.

To the left of the spool holder you can see a stator I just wound thanks to this spool holder.

Upper front view:

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Top down view:

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