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Battery BMS Repair or Replace


SinisterPrime
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Hey everyone

I've been a lurker for a long time around this website picking up what i can for my new love in the EUCs and i picked up a Zipwheel 16" as my first wheel back last year and have used it for about 5 miles daily up until last month when i was involved in a RTC with a speeding motorist i managed to get out the way but i was unable to get the wheel out in time and it was launched 15ft up the road cracking the case open and throwing the battery. I have since tested the wheel and it appears both the motor and the controller by some miracle survived undamaged as the case seems to have withstood the impact although is now in a sorry state and needs replacing, however the battery although worked for the tests didn't seem to fair as well its landing appears to have damaged something on the BMS PCB (Picture) and being that i don't know what its for i haven't dared to try and charge it  for my lack of knowledge in batteries and things i've read about them exploding or catching fire and seeing i have my baby girl in the house wouldn't risk it without seeking advice from someone who knows these things. I have since been without my wheel i have ordered a new battery but i would like to either repair the PCB in this battery or replace it as all the cells appear to be completely undamaged. This being the case i searched online for the same PCB so i could just swap them out but have have no luck in finding the board they used even seeing the model number on the front of it (A4-FL16s-DLC) didn't help me to source a replacement i have looked on aliexpress to see if i could find a different board to replace it with but i have no idea which ones would be suitable as i know they have ones for E-Bikes that would be dangerous on the unicycle, unexpected cutoffs and such and was wondering if any of you here may have had something similar or are more techy then myself who may be able to help me in sourcing a cost effective replacement board as i would hate to see these cells wasted

Thank you all in advance

BMS.jpg

Cellinfo.jpg

Edited by SinisterPrime
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@SinisterPrime, glad you are OK, that sounds scary!

 That BMS looks to be pretty much a standard BMS for 16s packs. There is a component, probably a transistor that looks to be burnt out just to the right of those two big silver squares. It is probably same as the two above it so could possibly be repaired if identifiable. The thin red and black wires go to the charge point and the thick red and black to the main board on the wheel.

To be honest, the 3 FET's on that board (big black things above the silver squares )look like they are there to cut power on high current/low voltage so that board is probably of the type intended for ebikes anyway. 

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I appreciate your reply, the damage seems quite severe in the sense there is scorch marks but not knowing what its a part of circuit is damaged i didn't want to risk charging it. So i need to source a replacement board for this battery pack but i'm not sure which ones i should be looking at or purchase as i am not so knowledgeable with battery packs like this as it is the first item i've ever owned thats needed one, and although i understand what the circuits on the BMS are for and a rough idea how it works i'm still abit confused as to what BMS to buy as i still find them abit confusing i assume from what i have read that i am going to need one that does cell balancing, over voltage protection and under voltage protection but i don't know what amp drawn should be what i use i know the motor in the zipwheel is only around 350w-400w do you know what boards would make a suitable replacement?

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A new BMS is around $30-42?  A new battery pack is about $114?  Even if the cells are all still 100% fine, the effort to disconnect all the wiring from the batteries and connect them to the new BMS might not be worth the $80 in savings?  It might be worthwhile to just get a new pack to get you rolling again quickly and keep the old pack to build a spare battery pack in the future if you can source a replacement BMS or replace the burnt out surface mount component.  One concern might be physical damage to the cells that you cannot see.  Say you are able to find a new BMS board and connect it all correctly.  If there are some cells which are damaged in the crash that aren't clearly noticeable, I wonder if charging them up would be dangerous.  Is saving $80 and spending all that effort in the repair worth the risk?

Edited by HunkaHunkaBurningLove
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Thank you very much your replies i have checked the cells around the outside and the whole thing was wrapped in plastic wrap then cardboard seems the out wrapping bore the worse of it but the BMS landed PCB down so took the damage.

12 hours ago, Chriull said:

To reuse the batteries you'd have to ensure, that the insulation between them is still intact and no cell has any physical damage

Acutal "good" BMS have all integrated Circuits to control the threshold and balancing and the limits have to be programmed. Here the example for the ninebot BMS:

i wouldnt want to waste these cells as i know they are good quality samsung ones but i know if i keep them at the low state of charge they are at now it will drop further and become unusable and seeing as i have a soldering iron and the kit i need to do the repair i would like to at least attempt it as if the cell insulation is damaged they can be rewrapped, the guy in my vape shop does them and worst case could use the cells for my vape or something

16 hours ago, HunkaHunkaBurningLove said:

keep the old pack to build a spare battery pack in the future if you can source a replacement BMS or replace the burnt out surface mount component.

this is my prefered choice but i really would need help selecting which BMS i could use and a place from which i can buy them if anyone has any items because for me even if this doesn't work i'm willing to try so i can learn and maybe in the future build my own custom battery pack for my EUC

12 hours ago, Chriull said:

Since the pack was thrown out of the case i would not repair anything - you'll never know if there are some small "cracks" which will "cut" connection by some mechanical or temperature change... Should be imho too much risk for a faceplate out of nothing...

i definitely wouldn't risk reusing this BMS now, you raise a good point so i will rule that out and look for a replacement instead

i also put more pictures of the rest of the pack to show you all

20160424_193849.jpg

20160424_193838.jpg

20160424_193653.jpg

20160424_193817.jpg

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I used this BMS to make my packs http://www.aliexpress.com/item/16S-15A-59-2V-li-ion-unicycle-BMS-PCM-battery-protection-board-bms-pcm-with-balancing/32414515852.html

as posted in this thread 

 

quality seems ok, although there are no sophisticated self balancing chips on it. I chose it, because it was easy to solder batteries to it (each battery can be soldered separately). hopefully i'll find time to test the batteries under controlled load this week to accurately check individual cell balancing and discharge/overcharge cut-offs. I'll be posting the findings in the thread above.

btw. before resoldering your cells to a new bms, I'd check the cells individually - it'd be quite a waste of effort if one or more of them is busted. at least measure the voltage on each cell and see if they are all equal.

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9 minutes ago, HunkaHunkaBurningLove said:

How can you tell if a BMS has self-balancing chips on it?

In the picture of the two boards mentioned here

49 minutes ago, HunkaHunkaBurningLove said:

OleTC mentioned this BMS.

You might try contacting him or read his thread to see how his build went.

Here's another one:

http://m.aliexpress.com/item/32422681053.html

you can see 4 small IC's. These are battery managment chips which should include balancing (to be sure one would need the datasheet). One can also see the 16 similar groups of (about 3 components) - in the first one divided in 2 groups of 8 and in the second one 4 groups of 4. These seem to be for the "external" balancing (which could be much more effective (powerfull) than the internal balancing included in the chips)

The first BMS linked has a cutoff discharge current of 40A +/- 5A which is imho not enough. Maybe with a 16s pack and a 350W wheel it could work - personally i would tend to a higher discharge protection current! The second has 60 +/- 5A which could be a bit of a narrow limit for a 16s2p pack. @Tomek's link has the highest with 80+/-10A. Personally i would go with the cutoff current as high as possible - just one faceplant reason less ;) The board can not really be seen on the picture but from the specs it should have about the same balancing as the other two boards.

I don't really understand in the specs of the first two links the supply voltage with 60V (would be 3,75V per cell for 16s) - makes no real sense imho and is hopefully a typing error...

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16 minutes ago, HunkaHunkaBurningLove said:

I thought 60v was pretty standard for these. Tomek's BMS has 59.2v which is weird.

With 16 cells between ~2,7V and ~4.3V it has to work within a range from 43 to 69 Volts. With maybe a higher upper limit for regenerative breaking

16 minutes ago, HunkaHunkaBurningLove said:

 What's a typical maximum amperage discharge rate for say emergency braking or hill climbing?

Hill climbing with a ninebot one e+ (15s2p pack and 500W motor) my maximum amperage was 42.16A driving:

and once 48,13A (had to jump off...;( ).

Regenerative breaking seems to have much lower peak amperages - but also i don't like to fall backwards or burn the mosfets, so normaly i do no emergency breaks. And from the fortionately seldom emergency break(s) (was imho just one until now) i have no logs...

And also as i like 9BMetrics very much it "only" has about 30 samples a second - so the real peaks could be much higher, and the numbers are delivered from 9Bot and ?noone? knows how exact they are...

 

 

 

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24 minutes ago, HunkaHunkaBurningLove said:

I thought 60v was pretty standard for these.  Tomek's BMS has 59.2v which is weird.  What's a typical maximum amperage discharge rate for say emergency braking or hill climbing?

i guess they just used 3,7v as average cell voltage (3,7v x 16 = 59.2v ) versus typically used 3,75v (3,75v x 16 = 60v)

it's just an indication, doesn't really matter, the battery's voltage changes as it discharges from maximum voltage (4,2v x 16 = 67,2v) versus full discharge cutoff (2,5v x 16 = 40v) (EUCs don't come close)

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Thank you very much everyone you have all been brilliant i may look at getting the BMS with the 80amp cut off save myself from any faceplanting

On 24/04/2016 at 10:22 PM, Tomek said:

but you have all helped me a great deal and should this happen again i know which ones to look for i'm hoping to get a bigger and better one soon as the small motor in my zipwheel and my 75kg 80kg weight is becoming abit of a problem i think as it does seem to strain abit with me on it and i have had unexpected cutoffs before on it which made me lose confidence with this wheel but i'd rather use this one with extra caution then be without one now so as soon as my New BMS i will fix the old pack and hook them together for extra safety maybe look at a gotway mcm3 or the Xima Lhotz for possible choices.

 

Edited by SinisterPrime
missed a bit and i am fatter than i thought
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42 minutes ago, SinisterPrime said:

Thank you very much everyone you have all been brilliant i may look at getting the BMS with the 80amp cut off save myself from any faceplanting...

It want save you from faceplanting - it just removes one cause for faceplanting :(

you still have cell undervoltage by "overpowering", etc...

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5 hours ago, Chriull said:

It want save you from faceplanting - it just removes one cause for faceplanting :(

you still have cell undervoltage by "overpowering", etc...

at least its one down though ;)

thats why i intend to upgrade soon but for the time been i think i will repair this pack with the new BMS have already ordered some xt60 parallel and t-plug parallel to hook the two packs up so i have a 16s2p to further reduce my risk of faceplants.

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  • 3 years later...
On 4/26/2016 at 2:14 AM, SinisterPrime said:

at least its one down though ;)

thats why i intend to upgrade soon but for the time been i think i will repair this pack with the new BMS have already ordered some xt60 parallel and t-plug parallel to hook the two packs up so i have a 16s2p to further reduce my risk of faceplants.

Dear SinisterPrime! 

If I connect 16s1p with one bms, and make another pack of 16s1p with a second bms, and connect them with T parallel and xt60 parallel splitter will it reduce the amperes to the bms, or should I make 16s2p with one single bms? 

Thank you for your answer 

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2 hours ago, Ch.Eng.62 said:

@Attila Demeter- Szatmári,

Well come to the forum.

Probably you didn't note that the post you refer is from April '16 and @SinisterPrime last visiting the forum is December '17

Thank you for the welcome, and for the fast reply. 

Can anybody please answer my question?

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3 hours ago, Attila Demeter- Szatmári said:

Dear SinisterPrime! 

If I connect 16s1p with one bms, and make another pack of 16s1p with a second bms, and connect them with T parallel and xt60 parallel splitter will it reduce the amperes to the bms, or should I make 16s2p with one single bms? 

Thank you for your answer 

Paralleled packs will share the current (if none is off by some protection circuitry)

1p configurations are at almost all EUCs overburdened and the cells will age faster.

The three points BMS fullfill with nowadays EUC is cell overvoltage protection, short curcuit protection (?except gotway) and cell balancing.

Cell undervoltage cut off is not used anymore, since this can lead to nasty accidents. Cell undervoltage warning would still be great to inform the rider of a "going bad" battery pack...

16s2p are common, two 16s1p could also make sense - depends on your requirements.

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18 hours ago, Chriull said:

Paralleled packs will share the current (if none is off by some protection circuitry)

1p configurations are at almost all EUCs overburdened and the cells will age faster.

The three points BMS fullfill with nowadays EUC is cell overvoltage protection, short curcuit protection (?except gotway) and cell balancing.

Cell undervoltage cut off is not used anymore, since this can lead to nasty accidents. Cell undervoltage warning would still be great to inform the rider of a "going bad" battery pack...

16s2p are common, two 16s1p could also make sense - depends on your requirements.

Thank you very much for your time and answer. 

I bought a noname chineese euc, which has 30v in battery's, and couldn't charged, so I decided to make new battery pack, but now not the original 16s1p, but I would like to use it to bigger distance, so would you like to use 32 cells.

Should I pay more for another bms for 2x16s1p

Or 

Could I use the original bms but in 16s2p if my requirements are these, sir? 

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42 minutes ago, Attila Demeter- Szatmári said:

Thank you very much for your time and answer. 

I bought a noname chineese euc, which has 30v

60V i assume? 16s makes 59.2V nominal voltage or 67.2V max voltage.

42 minutes ago, Attila Demeter- Szatmári said:

in battery's, and couldn't charged, so I decided to make new battery pack, but now not the original 16s1p, but I would like to use it to bigger distance, so would you like to use 32 cells.

Should I pay more for another bms for 2x16s1p

Or 

Could I use the original bms but in 16s2p if my requirements are these, sir? 

Many of the noname/first generation EUC have BMS with overcurrent cut off.

The wheel could be "designed" that with an 16s1p pack this overcurrent cut off (as good as) never happens - but with an 16s2p pack this cut off could occur regularly in high burden situations.

This possibility would lead to using one or two new BMS were one knows the exact specifications. If you use one or two is your personal flavored decision - depending what you get easier/cheaper and how you can build it up/put it into the wheel.

A second important point to consider is, that increasing the battery could lead to frying your wheel (in high burden situations), as you'll get this higher peak currents...

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