Parts all rated in AC. How to tell what their DC rating is?

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omegagamer89

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Aug 15, 2012
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I would say that plug is suitable only for charging a battery, so presumably your charger is at most 5 amps.

The problem is not so much the blades of the plug, but that it will wear and start making poor contact. Too poor for pulling a motor for example.

Ask us here about what plug is best for this, or that. Then we can tell you how the plug melted when we did this, or that.

There are some "what's your favorite connector threads".
 
The reason you won't find a DC rating for it is because it is for ~250V AC use only ;)

The AC/DC issue for switches and relays is different as contacts are less able to break a DC circuit than an AC one. This isn't really an issue with a connector, it's actually an issue of electrical safety.

Quoting Rod Elliot:

Extreme Warning: Never, EVER use a mains connector of any kind for DC. While it might be tempting to use an IEC connector (for example) for low-voltage DC, doing so is illegal and extremely dangerous. You might know what it's for, but anyone else will assume that it's a mains input (because that's what mains connectors are for - mains !).
Should a mains lead be plugged into your 'DC connector', the end result will be at best an entirely fried piece of electronic ash. At worst, someone could suffer an electric shock or be killed. YOU could then be charged with manslaughter, because what you have done amounts to wilful disregard for basic electrical safety and is clearly negligent. If the person survives, you can expect to be sued for damages, since the person affected did nothing wrong, but received an electric shock or other injury due to negligence on your part. Depending on the laws where you live, you may be charged with negligent homicide or similar (the legal wording might differ, but the end result won't be good for anyone involved).

Mains connections are for mains - nothing else, ever!
Click to expand...

http://sound.westhost.com/psu-wiring.htm

Whether someone uses a mains connector for DC is a personal safety judgement call, but it explains why you won't find a DC rating published anywhere.

BTW, I've founf Mr Elliot's articles on electronics very informative for a newbie to electronics, like me :)
 
There are dc connectors with dc ratings. Few cross-over products though.
iirc Mains connectors have good wear resistance but don't conduct quite so well. eg: Small signal wires might be gold plated, but gold plate just vanishes from power connectors if they spark. Most materials can be grouped into use for different contacts.

I should know more, but I made an early start as usual *hic*
 
Here is an example of the same switch being used for AC and DC, it shows the quite different requirements and should convince you to search out properly rated DC equipment for your EV.

https://www.youtube.com/watch?v=Zez2r1RPpWY
 
he is not switching anything. he just doesn't have a clue of what to use to make a connector from.

use anderson connectors or the Hobby King plugs. some people like the 4 mm and some like the 5mm. depends on how much current they wanna pull to prove their bike is better.
 
The issue is that that is the exact type of plug I need to use. My motor kit has this type of plug to connect the motor/controller to the battery pack: http://www.skycraftsurplus.com/images/products/detail/rp7516.jpg

And Id rather avoid having to chop that off and solder on a different type of plug. So then, the only option is that exact style of plug I linked to in my main post.

I had already had all this set up and my bike ran fine for months. However, ive since built a new battery pack (higher amp hours) and when I plugged it in, there was a spark at the point where the positive wire connected to the back side of the plug, leading to the battery, and it basically burnt the wire off of the plug. It never happened before, so Im guessing it was my crappy soldering job.

Anyway, my point is that I would like to avoid switching to a totally different type of connector if at all possible. I want to stay using this:
http://www.skycraftsurplus.com/images/products/detail/rp7516.jpg
http://ecx.images-amazon.com/images/I/51WGoTwjZAL._SL1500_.jpg


Are you guys saying that this type of plug is totally unsuited to DC?
 
the spark is caused when you connect the battery to the controller and the battery pushes current into the input capacitors of the controller. it will always do that unless you turn off the battery before connecting, leave it permanently connected, or use the precharge resistor.

you do not wanna use the wimpy connectors anyway. use andersons and either add a switch to the circuit current on the BMS like i do or build up one of the precharge circuits.

or you can open the controller and remove the drain down resistor across the input caps and leave it permanently connected and put the controller circuit current on a switch. use only real wire, not that rubber enclosed cable with the IEC plug on the end.
 
There is already a switch in the circuit. The switch was off when I connected the plugs, and then the spark happened when I flipped the switch and completed the circuit. As i said, I think the spark was a result of sub-par soldering right where the spark occurred.

As I said, I am not interested in using Andersons or anything else. As I made quite clear, I need to use these same types of plugs. The type of plug is not the issue. The plug itself did not spark or fail. It was the WIRE at the point where it was soldered ON to the rear of the plug.
 
I get it now.
You won't find that style with a DC rating.

Your painting a story where the plugs are the wrong way around. If your battery is presenting it's power at that male chassis socket it's wrong. The controller does not need the shielded female, the battery does. As the battery is male, it has exposed live parts and will accept a kettle lead. Somebody could easily think that is the correct charging method and bugger it right up.


How many amps are you putting through it? I would say 15 is about your lot and expect it to melt around 25 but I'm just guessing based on thermal limits. I have seen them melt used within spec, so over specifying is just daft.
 
Well the battery pack is a 12s. I ordered 12 individual 1s, 5Ah lipo cells and wired them up into two 6s packs, which I have in series. So then, that would be 60 amps right? (5 amps per cell x 12 cells)
 
omegagamer89 said:
Well the battery pack is a 12s. I ordered 12 individual 1s, 5Ah lipo cells and wired them up into two 6s packs, which I have in series. So then, that would be 60 amps right? (5 amps per cell x 12 cells)
Click to expand...
Ouch! Some one needs to do serious reading. Better droop it all and dedicate few days to read everything you find about Lipo's on this forum. Use links on following tread!!!!!!!!!!!!!!
http://endless-sphere.com/forums/viewtopic.php?f=14&t=26621
 
Are you sure you didn't have the polarity crossed? The black wire in AC cables do not necessarily correspond with the black (ground) wire in your battery...Did you check the polarities with your DMM?

:D
 
The plug is rated to 10A AC and you'll have no problem pulling 10A DC through it. You can likely put more through it, up to the point where you can feel it starting to get warm.
 
No, the polarity wasnt crossed. I checked it with my multimeter. Even if the polarity was reversed, that still wouldnt cause that kind of spark and burnt wire JUST from plugging it in.
 
omegagamer89 said:
........ Even if the polarity was reversed, that still wouldnt cause that kind of spark and burnt wire JUST from plugging it in.
Click to expand...

Sure it could, depending on how you had it set up. I once blew the tips off my multi meter probes when I accidentally crossed them while metering my 36v battery. Big spark and DDM probes 1/3 shorter...:lol:

Glad they weren't crossed on your side.

As for the OP, their doesn't seem to be a crossover rating that I can find. The big difference is that AC fluctuates (Cycles) and DC doesn't.

This one is related to airplanes.....

 
Well, you aren't going to get us to say that plug is a good choice for a battery to controller connection. You'd be better off even with some bare wire and wire nuts.

Andersons and RC hobby bullets are the main choices, because you can take that connecting spark on the tip, then slide the connector in further to get a solid connect.

The ac plug just ruins itself with the spark, toasting the contact area of the female plug. It's not so much an AC DC thing, as it is the result of the capacitors in the controller causing the spark.

There are threads on spark proofing your connector.
 
Ive got things figured out with the wiring and the plug, so I want to thank everyone for their help with that.

However, now I cant seem to find the right fuse. The fuse I had with the old battery pack blew right away. I was mostly expecting that, since the new pack is much higher power. However, Ive now gone through several different fuses that I thought should have been sufficient, and theyve all blown too. What confuses me is that they all blow as soon as I plug the motor in. Not even when Im USING the motor, just as soon as I plug it in, even without actually running the motor and putting any strain on the system. I could understand if the fuses blew when I put the pedal to the metal, but I can understand why they would possibly blow right away, when the system is essentially idle and there is no load because the motor is just sitting there, not spinning.

At this point Im so frustrated with this thing, I dont even want to know WHY these are blowing, I just want to know what fuse WILL work. Based on the battery info I gave before, and a 36v 800W motor, what voltage/amperage fuse would I need here?

As a related question (mostly out of curiosity) what would be the major risks of just taking the fuse out of the system altogether? Just that if the voltage or amperage goes too high, it could damage the motor or controller, right?
 
It sounds like you have a fault.

If you post up specifications for your battery, controller and motor that would help in the diagnosis. Photos of each would also help.

Data needed! ;)
 
i vote for bigger and bigger fuse until it doesn't blow anymore. if you need to have fuse above about 40A and cannot find bigger ones then solder two or three of the 40A fuses in parallel to get up to 120 or even 160A if you can and then solder the wires to the fuses. see how high you can go in fuse capacity before the fuse doesn't blow any more. see if it will go to infinity and beyond.
 
STOP! Fuse is for safety. Do not bypass. Something is not right with what you are doing. Draw a picture. Take a picture. Pay attention to + and -

What happens with a DC digital volt meter when you connect + and - backwards? Do you get a negative number? With my old analog meter the needle goes to the left when + and - are reversed.
1T032_AS01
 
marty said:
STOP! Fuse is for safety. Do not bypass. Something is not right with what you are doing. Draw a picture. Take a picture. Pay attention to + and -

What happens with a DC digital volt meter when you connect + and - backwards? Do you get a negative number? With my old analog meter the needle goes to the left when + and - are reversed.
1T032_AS01
Click to expand...

hey, that little voltmeter has a fuse inside. why not set the meter to read mA and then connect it in line to measure the current while testing it to make sure you really do have current in there. since the meter has a fuse it will be safe.
 
Punx0r said:
It sounds like you have a fault.

If you post up specifications for your battery, controller and motor that would help in the diagnosis. Photos of each would also help.

Data needed! ;)
Click to expand...

Im at work now, so pictures will have to wait.

The battery pack is 12 of these 1s cells, wired up into two 6s packs.
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=33117
The packs are then connected in series to the plug where the power cord for the motor plugs in. The fuse is between the batteries and the plug for the motor. There is also a switch just before the plug, so that I can connect the power cord to the motor, and THEN throw the switch to compelte the circuit. (It always blows the fuse as soon as I throw the switch)

The motor is a 36v 800w rear-wheel kit, and the controller is just the one that comes with the kit. This one;
http://www.ebay.com/itm/36V-800W-26-Rear-Wheel-Electric-Bicycle-Motor-Kit-E-Bike-Cycling-Hub-Conversion-/370982037638?pt=LH_DefaultDomain_0&hash=item566040a886

dnmun said:
i vote for bigger and bigger fuse until it doesn't blow anymore. if you need to have fuse above about 40A and cannot find bigger ones then solder two or three of the 40A fuses in parallel to get up to 120 or even 160A if you can and then solder the wires to the fuses. see how high you can go in fuse capacity before the fuse doesn't blow any more. see if it will go to infinity and beyond.
Click to expand...

I tried a 60amp 32v fuse last night, and it blew right away like everything else. There ARE no bigger fuses, other than ones that are literally 1000+ amps and cost upwards of $350 each. Ive searched around for two hours so far on google, amazon, ebay, hobbyking, home depot, autozone, component distributors, wholesalers, etc, and there is nothing in between.

You cant really parallel fuses like that. I mean, you CAN, but it wont work quite like youre saying. Unless the two fuses are EXACTLY the same, and the length of the wires on each one is EXACTLY the same as the other, they will NOT carry an equal load. The electricity will always take the path of least resistance, so if one wire is even a fraction of an inch shorter, then more power will flow through there. So then, two 60a fuses in paralell wont quite get me a 120a fuse. one of them will carry more load than the other. The one with the shorter wire might get, for example,52% of the load, and the longer wire will only take 48%. So we wont have 60+60= 120, it will be more like 68+52=120, with the shorter-wired fuse carrying 68amps and the other only carrying 52. (These numbers are just an example) Then, as soon as the heaveier-loaded one blows, the other one will immediately have to take all the current, and it will blow right away, too. I looked into that idea a few days ago, and its not workable.

marty said:
STOP! Fuse is for safety. Do not bypass. Something is not right with what you are doing. Draw a picture. Take a picture. Pay attention to + and -

What happens with a DC digital volt meter when you connect + and - backwards? Do you get a negative number? With my old analog meter the needle goes to the left when + and - are reversed.
Click to expand...
I know for a fact that the polarities are correct. I have double, triple, quadruple, quintuple checked this over and over. If I connect the multimeter with the polarity reversed, it shows up as the same number, but negative.


spinningmagnets said:
If the fuse blows as soon as you plug the battery in...and the motor is not even running...you have a short in the system.
Click to expand...

I have checked the entire system over and over many times. There is no short.
 
If no short ? Cut your off the end add andersons or 4 mm connectors plus an antispark precharged resistor and move on.
Throw away your old plug away so you won't use it again.
 
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