My kick scooter project

[ElectricGod]

From my learning the stranded cable is much better at eddy losses than solid core, I notice it uses the same casing as my brushed motor if I knocked the magnets off and refaced it the brushless inners may retro fit I hope I'll check dimensions I would only do this because I can not see any brushless motor casings local with a mounting bracket they are all same as yours mount at end caps rather than its belly they are only in hypertoys USA that come with bracket and direct fit on for a razor with a bit of cutting but it cost to much to import.
Won't the 14awg windind up the current flowing capability of the motor without producing as much heat but then run at a higher kV rating and then overvolt wont you have a 15000rpm+ rotor ? you may have to add more turns in the stator to lower the kV back down ? It will run like a tank i think you may not need cooling with a good rewind do a motor calc and hats off to you it will fly.
What I was thinking is the 48v may handle a litlle increase on voltage and current but only slightly so 60v 40a or 2400w peak a 60v 2500w controller I guess only way is try it for myself I think but from my understanding bldc motors don't overvolt as well as direct DC motors as well as your windings are stationary so naturally harder to flow air through them but try not to flow the air to fast there's a perfect range for carrying heat away but not creating a lot of windage losses ive read a lot of post of people sctraching they head with unexplainable unfathomable rewinds but I hope u crack it, because i want to follow suit in time lol .

Rewinding motors...Everything is a trade-off. My understanding is that the losses from lots of insulation due to many small wires is worse than the issues involved with a few large strands. Small wires have their own issues. Many small strands tend to not stay put, they move and vibrate and wear the insulation off of each other. Large strands don't move or vibrate so much so they don't wear against each other and cause eventual shorts.

I tried to get motors on alibaba, but the Chinese take tons of patience to deal with and they get all obtuse and uncooperative when you try to get straight answers out of them. I've asked the same question, worded different ways like 5 times and never get straight naswers. After a while I just give up and move on. The few times I have successfully dealt with Chinese sellers, it went well, but the rest of the time I never get past first base! Shipping was not the issue. IT was simply getting answers to simple questions. For example, I found a seller on alibaba for the 2000 watt BOMA I am using. We got as far as getting a price and then they wanted me to pay them by some weird way that had no guarantees that I would get anything. I asked for alternatives or even help with making the payment and they were all of a sudden totally unhelpful and acted like we hadn't just spent 2 weeks trying to buy a motor. Same for wheels, transmissions...you name it! I'm kind of burnt out dealing with Chinese companies. I can't imagine how they stay in business with the shit they put you through.

KV is realated to windings per tooth. It doesn't matter if you use 28 awg wires and there are 20 of them or if there are 2 14 awg wires. Its still the same number of windings to get the same KV.

Air flow...pretty sure I'm not pushing too much air. I could push twice as much air through and still be OK.

I can't speak to which motor type over volts better than another. Personally I think BLDCs over volt just fine. The issues are magnetic feild strength, heat, feild coil resistance, saturation...which apply to all motor types. I'm not sure what a direct DC motor is, but a universal motor or DC brushed motor have brushes and that is a huge waste of efficiency. Cars used to have points in them until electronic ignitions were invented and engine reliability was significantly improved. The same can be said of mechanical methods of switching magnetic fields. I'll take mosfet switching over brushed/mechanical switching every day of the year.

Rewinds...lol...I'll go with what works first and then once I have some experience and successes under my belt, I'll try some more "radical" rewinds. My first rewind will be with round 14 awg wire, but I am already looking at rectangular wire. The idea is to maximize how efficiently the space that windings fill is used and to waste as little as possible. Many small strands wind easily, but the losses from wasted space and insulation makes it a poorer choice. A few large strands with minimal wasted space is best.

 

[Ianhill]

I get you now your using the same cross section of copper but each strand is large now? So u get the same results as before but better quality cable , sad to hear the parts issues u have been getting, its a bit lapsy to only support large orders they will be feeling the struggle china has cornered the world market in most metals so we all dance to their tune at the moment upside is something's are getting very cheap but quality of some items is low I had a motor with the 8 hole vents on the end cap with the inner mesh and guard to hold it all down was not installed but stuck to the magnets inside lose to spin up with the armature needless to say lucky as it wouldn't turn by hand so I opened it to inspect and seen the terrible assembly if it spun up it would of sounded like a bag if hammers but it would of stalled and burn out I think.
Your the first I can find on net given these motors some loving they are a good choice really bearings easy to find easy maintenance and sprockets bolt up no potching or weak connectors and things to go wrong its simple and effective

 

[MrDude_1]

I get you now your using the same cross section of copper but each strand is large now? So u get the same results as before but better quality cable , sad to hear the parts issues u have been getting, its a bit lapsy to only support large orders they will be feeling the struggle china has cornered the world market in most metals so we all dance to their tune at the moment upside is something's are getting very cheap but quality of some items is low I had a motor with the 8 hole vents on the end cap with the inner mesh and guard to hold it all down was not installed but stuck to the magnets inside lose to spin up with the armature needless to say lucky as it wouldn't turn by hand so I opened it to inspect and seen the terrible assembly if it spun up it would of sounded like a bag if hammers but it would of stalled and burn out I think.
Your the first I can find on net given these motors some loving they are a good choice really bearings easy to find easy maintenance and sprockets bolt up no potching or weak connectors and things to go wrong its simple and effective

two larger 14ga wires fit and have a LARGER cross section than the 30-40 smaller wires that fit in the same area. You can almost double the area. You cant quite double the amperage because of cooling issues, but they can be lowered with an impeller pulling air through the motor.

 

[Ianhill]

Cheers Mr dude for explanation Iam rusty now long time since I learnt about motors, so by doubling the cross sectional area and keeping the turns same the current handling ability's will increase at the same no load speed giving more usable torque before hitting heat problems, I will like to see the results off this as these motors will be run of the mill for a good few years to come.

 

[Ianhill]

I can remember when I used to install the ac drives and induction motors with a few others i worked with some of the motors would be delta configured and others wye, in a wye the winding would have a reverse winding pattern, Delta winding has more speed less effeicent where as the wye winding pattern had loads of torque low I think the motor we talk of is a delta wound so should see some good speeds I best get saving a few Penny's I can get a motor fairly cheap UK stocked and Copper is cheap no better time to rewind than know.

 

[Ianhill]

So ideally u want the optimal thickness of winding for the current carrying capability you need then squeeze as many turns in as you can to give you as high working voltage as practical so you can exploit more rpm.

 

[ElectricGod]

Update...

The rewire is about done and was lots worse than I expected. I know that a hot phase wire melted a cat 5 cable I was using to run the back lights. It's what I had at the time and I was being cheap. LOL!!! The lesson here is do it right the first time or just don't bother! Anyway, the wire that got melted together ran to the back of the scooter to run the rear lights. Several wires in the cable shorted, got even hotter and then added to the whole melting problem. Since it was dark out, I had lights on so then the shorting issue continued to spread until the lights went out and then some smoke came out of the left switch module. That's when I became aware that I had a problem. I tried the switches a couple of times and then realized things had gone badly wrong what with the smoking switch cluster! I was able to salvage the smaller switch cluster, but the one that ran the horn, main lights and directionals was a giant melted mess inside. I had another switch cluster that I mistakenly purchased so now it is being used. I am also now using hi temp wire that withstands soldering temperatures everywhere and it's 26 awg instead of the barely adequate 32 awg patch cable wires. I still have a couple of terminations to connect to my wiring block and then double check I did everything right, but I should be finished tonight. Geez what a pain for using low temp wire!!!

I have also, replaced the feild/phase wires with 8 awg wires. That ought to take care of whatever I will EVER do with this scooter! I also ran them differently which shortened the phase wires by about 12". Originally I reused the hole that came out of the battery box for everything. There was no need for anything different and that meant my phase wires needed to be longer to route around the batteries and then out the left side of the battery box. The original hole was way too small anyway for the 8 awg phase wires so it made sense to drill out a new hole on the back right corner and run them straight out from the motor controller and save a foot of length in the process. I routed the hall cable out the new hole too. The LIPO battery packs are a little more crowded now and I don't need one of my cardboard shims anymore, but I think this will be much better over all.

My existing battery wires going to the controller are 8 awg and I have a 100 amp shunt connected to my watt meter. I'm not getting close to 100 amps so it's not a problem yet, but I'll probably upgrade my power wires to 6 awg and use a 200 amp shunt I have at the same time. I considered going to 4 awg, but that's probably waaaaay overkill.

 

[ElectricGod]

I get you now your using the same cross section of copper but each strand is large now? So u get the same results as before but better quality cable , sad to hear the parts issues u have been getting, its a bit lapsy to only support large orders they will be feeling the struggle china has cornered the world market in most metals so we all dance to their tune at the moment upside is something's are getting very cheap but quality of some items is low I had a motor with the 8 hole vents on the end cap with the inner mesh and guard to hold it all down was not installed but stuck to the magnets inside lose to spin up with the armature needless to say lucky as it wouldn't turn by hand so I opened it to inspect and seen the terrible assembly if it spun up it would of sounded like a bag if hammers but it would of stalled and burn out I think.
Your the first I can find on net given these motors some loving they are a good choice really bearings easy to find easy maintenance and sprockets bolt up no potching or weak connectors and things to go wrong its simple and effective

two larger 14ga wires fit and have a LARGER cross section than the 30-40 smaller wires that fit in the same area. You can almost double the area. You cant quite double the amperage because of cooling issues, but they can be lowered with an impeller pulling air through the motor.

what MD said...the only advantage the small strands have is they are easy to wind. Big wire is stiff and doesn't like to lay down around curves nice and tight. You have to prod and push it into place. Looking at my 80-100 and these BOMA motors, even with many tiny strands of wire the windings are not very tight. They are after all cheap motors...what can I expect?

 

[Ianhill]

Can't wait to hear how this goes , I had a look at a supplier for windings and some wires are not solderable some are I found some rectangular but as for finding the equivalent awg sizes its a bit of math to be done sizes like 3.81x2.5 and few others decent price though could be a good choice for many really the power it will deliever I can see you have put a lot into it and nothing ever goes smooth so I hope this 72v works out for you , I've worked out a way of fitting 72v 16ah lipo under my deck with a custom metal battery box extended under the motor as its now above deck ill gain 6inch depth in battery tray size in side i will be left with a long tall narrow gap a speed controller will fit for a fairly standard looking light maybe 40mph on the small wheels razor but should sound nice a electric motor rapidly revving upto 7000+ we will find out on razor mk3 brushless

 

[Ianhill]

My ammature seems to be around 28 turns hard to tell really of I think maybe 14awg not a bad job really all tight enough but i have read off a double rewind of 18x2 12awg is a good choice more speed on my setup but i not going to be throwing money at these motors as i really didnt want to buy a controller other than i seen what I had now delivered £20 so thought give it a go as the motors would only end up in junk pile I have had a look at brushes and after 30miles or so they are now wearing in a bit not so flat giving a small point of contact so should get a bit more efficent 16 miles harsh riding is plenty for now my packs at 3.8v rest then,
what's your range on all that ah ?

 

[ElectricGod]

My ammature seems to be around 28 turns hard to tell really of I think maybe 14awg not a bad job really all tight enough but i have read off a double rewind of 18x2 12awg is a good choice more speed on my setup but i not going to be throwing money at these motors as i really didnt want to buy a controller other than i seen what I had now delivered £20 so thought give it a go as the motors would only end up in junk pile I have had a look at brushes and after 30miles or so they are now wearing in a bit not so flat giving a small point of contact so should get a bit more efficent 16 miles harsh riding is plenty for now my packs at 3.8v rest then,
what's your range on all that ah ?

With spinning coils you can't get away with winding them loosely. The wires would wobble back and forth with the rotational forces and rub each others insulation off and probably break too. Loose windings on a brushed motor is a recipe for poor reliability. On a BLDC, the windings are fixed so loose windings are only effected by vibration and collapsing/expanding magnetic feilds and that is waaaaaaaaaaaay less than the rotational forces of a brushed motor. Regardless, look at a a real industrial grade motor...there's no slop in them. The windings are tight and neat and bound together so things can't move. That's the way to wind any motor!

I seriously doubt your brushed motor has 14 awg wire in it. I will hazard a guess...having never seen yours, but having taken apart a few motors that you probably have 20 awg or 24 awg wires. A 14 awg wire is a little more than the thickness of a number 2 pencil lead. 24 awg is about like a .7mm pencil lead.

Rewinding a brushed motor...
LOL! That would be interesting I'm sure, but IMHO...a giant waste of time if it wasn't like .5 hp or more. Regardless, the brushes are a huge failure point and the stators probably couldn't handle a lot more current if you did rewind one for torque. As a rock bottom minimum, I would double the brush size and wire 2 stator contacts together as if they were one contact. Of course that would kill RPMs which is the only real reason brushed motors survive very long anyway. It could be done that a brushed motor could be wound for 120kv, but don't load it very heavily or the brushes will burn up. Wind it for 250 kv and it will live lots longer!

LIPOS...
OK...I use them too. They are cheap and readily available at any R/C store, BUT!!! They suck. hahaha. No seriously LIPOs have their place, but in long term use they are a terrible solution. LION is far better. AND LIPO has much less charge density than does LION. The reason why the R/C world worships at the feet of the LIPO god comes down to cost, ease of use and weight. Back when everyone had no choice bu to run NiMh, large batteries didn't exist because they weighed way too much, but LIPO changed all of that. You can now get 20,000mah and still be a couple of pounds. However LIPO is easily damaged in several ways. Over charging, over discharging, physical damage, heat...LION is much more resilient, weighs less for the same Ah and will do almost double the charge cycles. I'm opportunistic...so I'll do LIPO for some things and then LION for others. I suspect that your LIPO batteries have seen a few charge cycles and are getting weak. If you do LIPO's (I'm not a LIPO hater), then build with double the capacity than you will typically use. OK yeah...it will weigh more and be a much bigger pack, BUT you can go a couple of days or more between charges and make your charge cycles go a lot further. Then charge only as often as you absolutely need to and NO MORE THAN THAT!!! You want to extend your charge cycles for as many days as possible. Oh yeah...and stay away from going down to 3 volts and as high as 4.2 volts. Charge to 4.15 volts and stop discharging at 3.5 volts and you will almost double your LIPO life span. There's one more thing too. LIPOs for R/C usage generally suck. The quality of the cells is less than wonderful and QC is usually mediaocre at best. No one takes a stack of cells and put them through their paces a few times before building them into a LIPO pack. R/C manufacturers basically take a stack of cells and slap them together and charge. If it charges to 4.2 volts per cell...well that's a good pack. Ummm...OKAY...but what about cells that charge to 4.2 volts, but have high internal resistance or have less than typical capacity. That's for the buyer to find! UGG! But hey...that's the world of R/C LIPO batteries for you!

Wire...
I looked around at motor places and wire suppliers and also ebay and amazon. I couldn't believe it!!! I found 14 awg wire (the exact same model number and manufacturer and hi temp stuff that wire suppliers sell, but for 20-30% less on amazon and then get free shipping too! OK so I don't buy in 10,000 foot quantities so I can get a serious price break, but I WILL take what I can get.

Rewinds...
I intend to rewirnd a 1500 watt BOMA and the 80-100 at virtually the same time. So there will be news, photos and failures/successes in the next few months. A spool of 14 awg wire will be on my doorstep next week. I went with copper wire...can't imagine not soldering to it! I once saw a motor made of silver wire...cost a fortune, but it was almost 98% efficient. I use 8mm bullets for everything over 1000 watts. No one can ever accuse me of underkill on motor connectors!!! I really need to buy a solid R/C motor controller to test these rewinds on! 100 amps ought to do it with minor loads. I just want to test the rewind on no load conditions to determine Kv and if it even works or not. Then I'll drop the motor onto my scooter and give it the real workout. It all comes down to maximum magnetic saturation possible. You will never get more torque than the NEO's can push/pull against. AND...efficiency suffers at higher Gauss levels. And while N75 magnets are possible, they cost a fortune and are really difficult to protect all that magnetism from heat. Hence the n35-n50 range used in most motors. They provide plenty of magnetic "push" or "pull" with much less volatility, cost and efficiency losses.

72 volts...
Nothing ever goes smooth...ummm tell me again who Murphy is? LOL...well yeah, but that doesn't stop me from trying. There's one thing to say about 72 volts or 60 volts...they are cheats. If you can't do it at 48 volts, then go on do it at more voltage with less reliability...that's a recipe for long term success...NOT! OK...over emphasizing my point. 72 volts is cool, but Ideally 48 volts is plenty, but it means a motor that has the KV to do what you want and the gearing to utilize it. Most of us (myself included) take what we already have and bump the voltage to get more speed at the cost of reliability. There is pretty much no speed limit you can't reach at 48 volts and 10 billion amps. Oh and by the way...all those batteries you used to up your voltage can now be used to up your current instead. I'll still build 72 volt systems, but its not ideal or the most reliable way to go.

Range...
I have no idea. I didn't dare find out because I didn't have motor cooling and then once I added active cooling I had a wiring meltdown from inadequate phase wires overheating. On my old 48 volt setup, 48 volts and 24,000mah I could go almost 24 miles at 25+ mph. It's anybodies guess what I can do now at double the Ah and 72 volts and 43 mph.

Congrats on finding room for more batteries!!! 40mph on an e-razor...that sounds like suicide by road rash waiting to happen! Can I ride it!!!

 

[Ianhill]

My electrical knowledge is very good i would of like too thought i did spend 4 years learning different electrical principle's 8 months on motors alone it never covered in depth motor rewiring but mainly the relationships between the different effects formulas for it all and basic rules etc
As for battery's.
I always learnt there's an 80% golden rule that you never discharge more than 80% of a battery.
Lipo prismatic cell.
Voltage sag is lower under load because it has a larger cathode area to cope with the current demand the discharge curve is higher up the voltage scale and stays flatter to the end of discharge from 4.20v to 3.8v that's a 0.4v drop at 80% depete but they suffer from the cold worse than other chemistry because their electrolytes are trapped in a polymer solid also because the cathode is so large its it's down side and that's the failing point over time so it won't reach as many discharge cycles as a 18650 no matter what charging method.
18650 cell.
The discharge curve is more linear from 4.1 to 3.50v at 80% theres more voltage drop noticeable 0.6v drop but it has a liquid electrolyte so better temp resilient still the cathode surface area is many times smaller so even with fancy materials and nano coating it will not deliver as much current if its a 1s vs 1s so thats why you have to parallel 18650 cells alot more than you would lipo but when lipos mistreated they result in swelling and if mistreated further the pack can split wide open and lithium can oxidize with the open air bursting into flames but that's an extreme case of negligence like having a rucksack of lipos to boost range they should be in a sealed compartment that can not vent at you.
My lipos are brand new I charge to 4.20 because I will use the pack straight away always obey the 80% golden rule and use a bleed discharge to reach a storage charge, i take the rated c as the maximum c so not to stress the battery's I use a 16ah 12s configuration 3 packs 4s2p so a 4s8ah x 6 for the price I could replace my lipos twice and have change compared to an equivelent 18650 pack 18650 must spend many years in a car so are a good choice but as for lipo 1 or 2 years heavy use and they would need to be changed but I still i feel lipo is a slightly better performer and take up less space like for like its a no brainer to me but that's my situation and view space is tight plus what's available in the UK where 18650 are either fraud or ££££ and rc hobbie suppliers are plentiful and lots of deals to be had so think wisely safely and most of all ENJOY.

 

[Ianhill]

The resistance of a new typical lipo is around 5milli ohms and on a 18650 is around 120milli ohm i know this from experience not stevie wonder saw this or joe bloggs said that. And that's why I would never mix these chemistrys they are in no ways paired in resistance or voltage characteristics to act the same in a group, electric always takes the path of least resistance or so nursury said meaning the lipos will deplete sooner than the lazy 18650 and pick up more of the ah under loading. lipo can deliver alot more current singulary really they cannot be compared in c rating but theres other factors that are key for public use in homes etc safety longevity and rc guys want big power and can swap out easily its not the same for a tesla so they go with 18650 cell for lots of factors its better but in my case temps not an issue and lipos discharge curve wins it for me.

 

[ElectricGod]

Friday night I got most of the way through the rewire and realized I had some mistakes in where stuff was terminated on my terminal block. I was trying to reuse the terminal block wiring as it already was laid out. I decided to pull all the wires off of it except power and start over. When I wired up the terminal block the first time it was somewhat haphazard and I never documented what each position was. Redoing everything was a good idea and I got it all correct the first time except my back directional lights were reversed. That took loosening 2 screws and swapping the wires and I was good to go. Now every position on the terminal strip is documented both by wire color and what it connects to. MUCH better!!! Well the batteries were sitting at 83.4 volts, so after testing everything multiple times on my stand, I was ready for a ride. It took me part of Saturday to finish the wiring reorg and testing. While I was in there, I replaced the cheap low temp wires on several things with the hi-temp 26 awg wire I bought after the meltdown. I shouldn't have any problems with wires melting anymore. The motor field wires are now 8 awg and a foot shorter than before.

Sunday (today), I took it for a ride. I attached my camera to the scooter to record the event. Anyway, the video is 41 minutes long and the ride is right at 13 miles. It's along bike paths around my city. There's places where I could ride full out (40mph) and did and of course around people there was no way I was going to pass them faster than 10 or 15 mph. Anyway, every 3 or 4 miles I would stop and put my hand on the motor in various places. I have a thermometer for it, but don't have it mounted yet. The air temperature is in the 50's F with some wind and the motor never got more than 80F or that's about all the warmer it felt to my hand. There are several places on the ride where there are 6 degree hills and the 1500 watt motor with 25 pounds less weight would struggle to pull me up them. The 2000 watt motor and battery enhancements had no problem accelerating nice and strong up the hills. The last part of the ride is about 1.5 miles on the road. The first half of that is up a 5 degree hill and then about .5 miles on level roadway before I get back to bike trails again. Anyway, since I had a nice long straight path where I couldn't possibly risk hurting anyone, I just floored it all the way once I got to the level roadway. I held 40 mph for about .5 miles and mostly kept up with the cars. Changing lanes to cross over to the bike path wasn't the normally scary adventure of being 10-15mph slower than the cars.

I started at 83.4 volts and ended at 71.2 volts under load after riding for 13 miles and 41 minutes. While on the .5 mile straight away going 40mph, battery voltage dipped to 68 volts, but I was pulling 40-60 amps continuous for a mile by then and at the end of the ride! Acceleration was really strong the whole time. At any speed over about 10-15 mph, the motor comes into it's own and if you crank the throttle a little, the motor just takes off. I think my throttle positioning in the Kelly motor controller can be adjusted a little to make the low end torque better. I have it set to an exponential ramp which makes taking off from a stop a little slower, but then it just takes off. The idea was to not cog badly and burn out the motor at low RPMs. I'll fiddle with the throttle setting some later after riding it to and from work for a while. I still don't know how far I can go, but 13 miles with no feeling of loss of performance was spectacular! My old LIPO packs by themselves were getting pretty saggy after 10 miles of use on the old setup. Reusing the old LIPOs and all the used laptop batteries is working out quite well. I checked the motor one last time once I got home again after that 40mph run at the end and it never got too hot to touch...I'm guessing 100F. The blower and heat sinks worked perfectly. I left the blower running for several minutes anyway and the motor was room temperature in about 10 minutes. I'm pretty happy with things as they are right now.

I opened up my LION battery box. It has never seen a ride longer than 5 miles so I was curious if there was any evidence of battery heating being a problem. The cells raised the temperature in the box to about 80F, but none of the plastic battery holders show any evidence of melting or heat damage. I'm going to call that good enough for now. Maybe on a hot summer day with the black grip tape on the top of it soaking up the heat, maybe they will get too hot then. The LIPOs never got very warm either. I put some hi density foam on the feild wires inside the battery bay to see if it would melt or not. The foam since it's all tiny air bubbles doesn't take much heat to melt. There was zero evidence of any heat issues in the field wires. There better not be! They are 8 awg wires now. The wires have almost no air space around them since they are crammed between the metal wall and LIPO packs. I still have 6" lengths of 12 awg coming out of the motor, but they have lots of open air flow around them.

Next up will be rewinding a 1500 watt BOMA with 14 awg wire. I'll probably extend the rewound motor wires out of the motor and attach 8mm bullets directly to them. That way there wont be any intermediate silicon wire connections. In the 2000 watt motor, I have 12 awg wires soldered to the ends of the motor windings. This isn't ideal, but I have no choice since they are too short to extend out the motor case. The motor case is identical to the 2000 watt version so adapting my blower manifold to it will be stupid easy...pop it off the 2000 watt motor and onto the rewound motor and I'm done. I got the 14 awg wire yesterday. I can't wait to see what a rewind will do for a cheap Chinese motor! The windings are poorly done, loosely laid down and made up of many 30 awg strands. There's tons of wasted space in the teeth as a result. I'm pretty sure I can do a way better job!

 

[ElectricGod]

The resistance of a new typical lipo is around 5milli ohms and on a 18650 is around 120milli ohm i know this from experience not stevie wonder saw this or joe bloggs said that. And that's why I would never mix these chemistrys they are in no ways paired in resistance or voltage characteristics to act the same in a group, electric always takes the path of least resistance or so nursury said meaning the lipos will deplete sooner than the lazy 18650 and pick up more of the ah under loading. lipo can deliver alot more current singulary really they cannot be compared in c rating but theres other factors that are key for public use in homes etc safety longevity and rc guys want big power and can swap out easily its not the same for a tesla so they go with 18650 cell for lots of factors its better but in my case temps not an issue and lipos discharge curve wins it for me.

Mixing battery chemistries...
That was my opinion too until talking to a couple of gigawatters on ES about reusing my old LIPO cells and expanding my voltage and capacity. I was going to make 20S1P packs out of my old LIPO's and buy more of the same LIPO cells to make new 20S1P packs out of new cells. One of those gigawatters referred me to a thread about mixing LIPO and LION batteries. My first response was the dude didn't plan ahead enough so his LION batteries had enough capacity to run his EV. The real answer was different. He did it because he had a small prebuilt LION pack and knew it wouldn't run his EV by itself so he used a bunch of LIPO bricks too. The end result was it worked as well as the LIPOs did. I have checked my LIPO cells and LION cells to see if they discharge differently and they don't really. I have 3 LIPO 20S1P packs in parallel with 7 20S2P LION packs and they all discharge at pretty close to the same rate. The LIPOs are not suffering because of their lower Ir. I think if you did a 20S1P LIPO in parallel with a 20S1P LION, well that might be different.

LIPO vs LION...
LIPO cells compared to 18650's are not dealing with the same constraints. A LIPO cell can be physically whatever size you can get. An 18650 has a fixed physical volume that dramatically limits what you can do with that volume. So of course you can put giant plates in a LIPO and get 80 amps continuous. LOL! Getting that out of an 18650 is probably impossible even with 100 years of further development. So do an apples for apples comparison. Buy the best LIPO cell you can get with the same physical volume as an 18650. Compare it against a samsung or LG 3100mah 5C 18650 cell and see which one works better. The 18650 will destroy the LIPO. Probably the LIPO cell will have maybe 1000mah capacity at 1 or 2 C. LION IS a lot better. Ask why Tesla uses loads of 18650's rather than giant LIPO cells...because the 18650 is not lazy and smashes the performance of any LIPO. Never mind that a LIPO will get you 200-300 charge cycles and an 18650 will get you more like 500 charge cycles. AND that's for good quality LIPOS and average quality LIONs.

 

[ElectricGod]

I bought a couple of 50 amp 20S BMS boards a while back. I intended to use them as balance chargers and run without a BMS in the scooter. The idea was to make balance charging quick and easy. A lot of people use an R/C charger to balance their cells and it takes them all weekend to do it. I know because I've done it myself! My idea was to use a 20S BMS as a balance charger so an entire 20S pack could be balance charged all at once. I would use my 84 volt charger as the power supply for balance charging. The idea works great and I balance charge an entire pack in an hour or so. I got the brilliant idea of parallel charging several packs at once from an R/C LIPO parallel charging articular I read a few months ago. It worked superbly well. All the individual cells in all the parallel packs charge correctly. The cells that have more voltage in them are pulled down by the cells that are low so that in the end all cells in parallel end up at the same voltage.

One of my LIPO packs is not the best anymore and so I needed to watch it more closely than the other 2 packs. I noticed that one of the cells in that pack got run down quicker than the rest of the cells in the pack. It's weak and I should replace it, but taking apart a battery pack is a royal pain so I'm putting it off until it gets much worse. The BMS and the other parallel cells will keep the weak cell from discharging too much. I have all 3 battery packs on the one BMS now. My LIPO packs have four 5S balance connectors so I added 3 sets of 4 balance connectors in parallel to the BMS. Last night I charged all 3 LIPO packs simultaneously via the one BMS. I then checked the packs individually when the charge was done, all the packs were balanced properly. Since it worked so well, I decided to just leave it in the scooter. There was a small space between the battery packs that was an ideal fit for the BMS. I wrapped the BMS in kapton tape several times to avoid any possibilities of random shorts.

This is the weaker pack charging on the BMS.

All 3 packs charging at the same time.

Everything in the scooter. There's no room in the battery bay for anything else. It's pretty much crammed packed with stuff now. The balance wires are way long, but when I put it all together, I didn't intend to leave the BMS in the scooter. Ah well, they are coiled by the XT60 connectors...good enough. The BMS is right underneath that clump of balance wires. It can't get any air flow around it, but there was no other place to put it. I used to run 4 30 amp BMSs on my 4 old 48 volt battery setup and they were buried under layers of kapton too and they never had overheating issues. I'm hoping the same will be true here too. I know the BMS is good for about 50 amps and I peek out at 80 amps and the LION batteries are running in parallel with the LIPOs too so I'm probably OK.

 

[ElectricGod]

This morning I rode into work (5 miles). I have noticed that I drop about 2 volts very quickly. From a full charge (81.5 volts) within 1/2 mile I'm down to 79 volts. Then voltage stabilizes a lot and drops much more slowly. Well...I got 100 feet from where I lock up my scooter and realized I didn't have my cable lock so I turned around and went home to get it (5 miles). Ran inside the house, got the lock and headed back to work. (what an idiot!). I have a thermometer on the motor now so I know what temps I'm actually running at rather than guessing. It's a little hotter than my guesses, but not much more. The hottest I saw the motor get was 124F while riding. I suspect wind made that number a little lower than reality. I also checked it when I got back home and it was just sitting there off and it went up to 156F. After returning to work (another 5 miles), the motor was running at 114F. This is all within safe margins since the windings can take a lot more heat than that. I still need to work out a blower controller so the blower runs separate from the key and shuts off automatically once the motor cools down. Turning the blower on via the key is fine. I don't care about it running when I'm riding. The motor will heat up soon enough anyway! Right now the blower is on the 12 volt DC-DC converter that gets shut off via my mosfet switch that activates with the key switch. A simple 555 timer circuit that runs for 10 minutes after the key is turned off would be enough to dump 80% of the motor heat and wouldn't depend on temperature at all. I like the KISS principal!

After 15 miles of continuous riding, battery voltage had dropped to 72 volts. An hour later it has "recovered" to 76 volts. My hope is I can go 2 full days or more on a charge. If I get to 65 volts (3.25 volts per cell) tonight getting home, that will be a good safe cut-off that I can happily live with.

 

[Ianhill]

Been on a little break so only today I seen your updates glad to see she running well and in use the voltage drop at the start is a normal on my jellopy I fall to 4.1 fairly rapid 1 mile say, I use the icharger 1010b+ for me they offer great options they can perform an internal resistance check of multiple cells in a pack upto 10s and pack total resistance and it has a USB to connect to a laptop etc and perform a discharge graph so by looking at my voltage under no load I know exactly where im in my discharge curve without adding up all the capacity ive used. 15 miles is not bad at all I find stop starting to create most heat and lower the pack ah quickest at top speed for long duration I generate very little heat and use power in its most efficient way I would proberly reach around 20miles on a flat at top speed, I missed out in a secondhand lyen12 fet controller in UK. I didn't get it as it was setup for 24v so needed a resistor swap for 72v and no programming lead so bit of a risk

 

[ElectricGod]

Been on a little break so only today I seen your updates glad to see she running well and in use the voltage drop at the start is a normal on my jellopy I fall to 4.1 fairly rapid 1 mile say, I use the icharger 1010b+ for me they offer great options they can perform an internal resistance check of multiple cells in a pack upto 10s and pack total resistance and it has a USB to connect to a laptop etc and perform a discharge graph so by looking at my voltage under no load I know exactly where im in my discharge curve without adding up all the capacity ive used. 15 miles is not bad at all I find stop starting to create most heat and lower the pack ah quickest at top speed for long duration I generate very little heat and use power in its most efficient way I would proberly reach around 20miles on a flat at top speed, I missed out in a secondhand lyen12 fet controller in UK. I didn't get it as it was setup for 24v so needed a resistor swap for 72v and no programming lead so bit of a risk

Motor controllers are so easy to abuse and EV experimenters are the worst. We blow stuff up all the time. LOL. I would be somewhat skittish about buying a used one.

I haven't charged yet...I'm now at 20 miles and will be at 25 miles by the time I get home tonight. When I got to work this morning I was sitting at 69 volts under load. Who cares what the recovery voltage is...that last like 10 seconds. Whatever I have left when I get home, I'll call that my bottom or discharged level.

 

[ElectricGod]

Well I'm am moving in multiple directions all at once it seems.

I've built a couple of 84 volt chargers out of a single 24 volt, 25 amp Meanwell power supply and several DC-DC up converters. They work pretty well as long as I limit the output current to about 6 amps. I like the output voltage adjust ability I have. I can set my output voltage to anything between 26 and 90 volts.

Then I've purchased 14 awg wire to rewind an 80-100 and a BOMA motor. I'll get that started as soon as I get them taken apart. I still don't know how I'll push the bearing carrier off the iron on the 80-100 without damaging something. I have everything needed to push the stack out of the BOMA inrunner. I just need to build it into a press. Rewinding it will be interesting. There are no gaps between the teeth. You basically keep feeding the end of the wire through over and over until you get a tooth wound. UGG!

Then I'm purchasing a Lightingrods 3000 watt motor to go on this scooter. The 2000 watt motor is running great and i can do 40-45mph without issues, but I have so much battery capacity now that I might as well turn a little more of that into torque. The 2000 watt BOMA has like 100 miles on it now and I'm already replacing it. That's not the fault of the motor, but rather me wanting to push my speed higher. I guess a fool and his money are soon parted is true after all! I have been impressed with the BOMA motors. They are uber cheap, but they do the things they are supposed to do pretty well. If there was a larger version of this motor, I would buy one! Once I have the 3000 watt big block on my scooter, I'll take apart the 2000 watt BOMA and rewind it. I am very curious to see what its potential can be.

Then I'm looking at my next project. I found a much smaller electric scooter that weighs 22 pounds. That's about 1/5 the weight of my existing one. It's a little over half as long and has 8" pneumatic wheels. It has a brushed motor on it and an enormous battery bay for its size. I'm seriously thinking about buying one. The frame quality is quite good, but the electronics, motor and battery are garbage. Well that's fine with me! Guess what I will be upgrading anyway? The steel frame cradles a plastic battery box. I'll be replacing that with a custom built aluminum box that is a little larger. The brushed motor mounts to a bracket on the frame so that makes mounting a new motor so much easier since I can reuse the structure that's already there. It lacks a front disk brake, but that's easy and cheap to add. This little scooter is a ready to be modded design. I think with an 80-100 I can get her moving easily into the high 30's if not 40's speeds.

 

[ElectricGod]

I've had a mini 200 amp shunt for a good while now, but didn't want to use it until I had wire to run to it. My 100 amp shunt is 4" long. The 200 amp shunt in 2" long. I ordered some 6awg wire that finally arrived on Friday. I have been running 8awg wire from my distribution buss to the motor controller, but the motor controller has an 8awg and 10awg wire for plus and minus power. Anyway, the 6awg wire finally gets me to parity between the buss and the motor controller. I also had used a couple of 8mm bullet connectors to allow me to disconnect the shunt from the system, but they are just extra connections that don't serve any real purpose so I eliminated them on the new shunt. I had made a mistake when I built up the first shunt and cut one of my wires way too short so I had an extension on it to get it to the motor controller. Well all of that is done away with now and takes up much less space than before. The shunt on the left is the 200 amp mini shunt and the one on the right is a crappy shunt I got out of China. I took this picture before I modified it, bit I drilled and tapped holes on the sides of the shunt so that I could push the wire through big hole and then clamp it in place with set screws. It worked pretty well. I tinned the ends of the 6awg wires where they go into the shunt holes. It works pretty well. The wires are very secure in the shunt. The electrical tape just insulates everything. The deans connector connects to the watt meter.

This is the new 200 amp shunt with 6 awg wire next to the old 100 amp shunt with all the extra connections on it.

 

[ElectricGod]

I rode into work today on the new shunt and wires. I couldn't tell there was a difference...I guess it worked. Next up is a bigger motor!

 

[ElectricGod]

I don't know what happened tonight. The motor has been running fine. Going hard 40mph on it gets it kind of hot (150F), but then it cools down again. This morning it was fine. I topped out at 124F. Tonight I rode about 2 miles doing like 25-30mph I looked down at my temp gauge and it read 200F. All of a sudden the motor makes a weird sound and smoke poured out of it. The blower was running it wasn't due to air flow or no cooling. I looked in the vent holes a couple of days ago and the windings were fine. This happened all of a sudden. Well the motor is fried. Looks like I'll be rewinding it sooner than I thought! You could say that I was really surprised that the motor went up in smoke so suddenly. The Motor controller is undamaged. I hooked up my 1500 watt motor and it runs on the controller just fine. I'll just set the amperage low enough to run it for a while until I get another motor that's more powerful or rewind my 2000 watt motor. The 3 mile walk home was fun! This motor has less than 200 miles on it. I'm guessing there was a problem waiting to surface all along.

 

[Ianhill]

Thats cooked fair play only 200miles too
Ive found a monster lifepo4 cylindrical cell its a 50ah 55380 2000cycles or 10-12years have a look might be right up your street for needs I now u like a bit if power .

 

[ElectricGod]

Thats cooked fair play only 200miles too
Ive found a monster lifepo4 cylindrical cell its a 50ah 55380 2000cycles or 10-12years have a look might be right up your street for needs I now u like a bit if power .

My used laptop batteries are working great and they were virtually free so I'm pretty happy with that aspect of my scooter. I'm starting the planning process of building out a 23 pound scooter. I wont have room for tons of crappy cells on it so I'll have to go with good cells for it to run effectively. It will have 8" wheels and hopefully do 35mph on a rewound 80-100 outrunner.

The motor failure was sudden. There was no evidence that there was a problem until it momentarily stuttered and then lots of smoke came out of it. I'm guessing that there was an insulation wear issue or already damaged insulation that shorted together. I'll rewind it with 14 awg wire. I think it's currently wound with 9 winds per tooth with 13 or 14 strands of 18 awg wire. With 14 awg, I'll be able to get a couple more winds per tooth which will bump the Kv a little. Also, larger wire wastes space less on each tooth so that should help too. The windings on these motors aren't very tight and they secured the wires with zip ties. All of them were melted through when I took the motor apart.

It's the nature of the motor...these BOMA motors are cheaply made. Anyone else would charge $100 more for one and wind it much better than this. Failures are bound to happen with less than ideal windings.