36volt BMS board help

six9giant

Pedelecer
Apr 16, 2016
73
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Maryport, Cumbria
Yes, I thought that also and he got £40 for a knackered battery, which annoyed me badly, I just put it in the cupboard and forgot about it, until last week.
Asked the local guy for help, he has already fixed two different batteries for me that had corrosion damages to internal wires.
 
D

Deleted member 4366

Guest
Probaly too late now, but paypal will refund you if the item was described as working, but wasn't. I don't know what that capacitor does. It doesn't seem to be across the main battery wires. There's another one there. I've got a feeling that it's something to do with that 8-pin plug. This battery must be a special one of some sorts.

Coming back to your 13.6v. That only means that the BMS is switched off. My suspicion is that there's a switch on that multi-pin connector. Was there ever anything connected to it? I've seen it now on Ebay, where there doesn't appear to be anything on that connector. Maybe it's a programming port or something like that. Did you check the individual cell voltages,which should be done before thinking about another BMS?
 
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six9giant

Pedelecer
Apr 16, 2016
73
10
66
Maryport, Cumbria
Probaly too late now, but paypal will refund you if the item was described as working, but wasn't. I don't know what that capacitor does. It doesn't seem to be across the main battery wires. There's another one there. I've got a feeling that it's something to do with that 8-pin plug. This battery must be a special one of some sorts.

Coming back to your 13.6v. That only means that the BMS is switched off. My suspicion is that there's a switch on that multi-pin connector. Was there ever anything connected to it? Do you still have a link to the Ebay listing so I can see what you bought?
The battery is still sold by Bankrupt Bike Parts, I'll just check for a eBay number for you. Brb
 

soundwave

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May 23, 2015
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anotherkiwi

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Jan 26, 2015
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Looks like a right fly by night operation... well spotted sw
 
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six9giant

Pedelecer
Apr 16, 2016
73
10
66
Maryport, Cumbria
Talk about it in the morning again, thanks for the help so far and hope we can reach a happy conclusion, as I feel it can be saved somehow, brick walls are always meant to be dismantled and rebuilt in a hypothetical way
 

soundwave

Esteemed Pedelecer
May 23, 2015
16,921
6,516
Paypal time limits
A buyer must open a dispute via the Paypal Resolution centre within 180 days of making the payment. This is an extension of the 45 days which it was previously. Buyers are encouraged to deal directly with sellers to resolve the dispute.

http://www.which.co.uk/consumer-rights/problem/am-i-protected-when-selling-with-paypal

open a dispute with pay pal and get ur money back,that thing could of exploded or burnt ur house down worst case.

its not worth even trying to repair it tbh as the cells are prob knackered anyway.

  • THIS IS NEW OLD STOCK POWER OUTPUT HAS BEEN TESTED BUT NOT CHARGED
  • how can you test the power output if it has not been charged???
 

soundwave

Esteemed Pedelecer
May 23, 2015
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Address:
Bankrupt Bike Parts
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West Midlands,
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Telephone:01384 568521

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C

Cyclezee

Guest
The eBay seller has 99.8% positive feedback from almost 140,000 which sounds great, but the 54 negative over the last 12 months would have put me off.
 
D

Deleted member 4366

Guest
The eBay seller has 99.8% positive feedback from almost 140,000 which sounds great, but the 54 negative over the last 12 months would have put me off.
I don't think OP bought it directly from them. My understanding is that he bought it from somebody that did.
 
D

Deleted member 4366

Guest
I've been studying that BMS. It has some unusual features, but most of it is normal.

As far as I can see, there's no damage other than that capacitor. Why does your electrical guy say it's completely blown?

My guess is that the blown capacitor doesn't do anything, and your problem is elsewhere. You need to get a voltmeter to measure the voltage on the cell-pack side of the BMS, i.e. on those big black and red wires at the top of the photo, and then, keeping our black probe on the big black wire, probe each of the pins on the back of the 13 pin connector. That will tell us what's wrong and whether you can do anything with it.

The BMS PCB is configured for 12 chanels, but 2 remain unpopulated. That means that two of the pins on the 13 pin connector are not used. A standard BMS will have a 9, 10 or 11 pin multi-connector, so you'd have to cut off the present one and splice all the wires to a new one. Hopefully, you won't need a new BMS.
 

six9giant

Pedelecer
Apr 16, 2016
73
10
66
Maryport, Cumbria
I've been studying that BMS. It has some unusual features, but most of it is normal.

As far as I can see, there's no damage other than that capacitor. Why does your electrical guy say it's completely blown?

My guess is that the blown capacitor doesn't do anything, and your problem is elsewhere. You need to get a voltmeter to measure the voltage on the cell-pack side of the BMS, i.e. on those big black and red wires at the top of the photo, and then, keeping our black probe on the big black wire, probe each of the pins on the back of the 13 pin connector. That will tell us what's wrong and whether you can do anything with it.

The BMS PCB is configured for 12 chanels, but 2 remain unpopulated. That means that two of the pins on the 13 pin connector are not used. A standard BMS will have a 9, 10 or 11 pin multi-connector, so you'd have to cut off the present one and splice all the wires to a new one. Hopefully, you won't need a new BMS.
My repairer didn't say the whole board is blown, just that capacitor had blown to smithereens.
he has never worked on a Lithium battery before, so this like myself, is uncharted waters etc.
Why I turned to you guys for help.

Thanks to all the fellow members for your contributions so far, much appreciated.
Bryan
 

craigp

Just Joined
Apr 18, 2016
4
2
40
I've been studying that BMS. It has some unusual features, but most of it is normal.

As far as I can see, there's no damage other than that capacitor. Why does your electrical guy say it's completely blown?

My guess is that the blown capacitor doesn't do anything, and your problem is elsewhere. You need to get a voltmeter to measure the voltage on the cell-pack side of the BMS, i.e. on those big black and red wires at the top of the photo, and then, keeping our black probe on the big black wire, probe each of the pins on the back of the 13 pin connector. That will tell us what's wrong and whether you can do anything with it.

The BMS PCB is configured for 12 chanels, but 2 remain unpopulated. That means that two of the pins on the 13 pin connector are not used. A standard BMS will have a 9, 10 or 11 pin multi-connector, so you'd have to cut off the present one and splice all the wires to a new one. Hopefully, you won't need a new BMS.
I thought it would be easier if I reply here on behalf of bryan.

I have tested the dc input and have the correct voltage of 42v.
I have tested each wire on the white connector whilst charging (green light on charger) and the voltages are as follows :

Pin 1 - ground
Pin 2 - 3.4v
Pin 3 - 6.79v
Pin 4 - 6.90v
Pin 5 - 10.37v
Pin 6 - 13.85v
Pin 7 - 14.13v
Pin 8 - 14.14v
Pin 9 - 14.13v
Pin 10 - 14.3v
Pin 11 - 14.3v
Pin 12 - 40.8v
Pin 13 - 41.9v

The blown area on the bms has been cleaned and I have probed the pads and found 42v on one pad which has continuity with the dc input, However I do get 42v direct to the battery when charger is connected so you are probably correct in the blown component is unrelated

I have also tested all of the larger components on the board and all are working ok.
 
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six9giant

Pedelecer
Apr 16, 2016
73
10
66
Maryport, Cumbria
I thought it would be easier if I reply here on behalf of bryan.

I have tested the dc input and have the correct voltage of 42v.
I have tested each wire on the white connector whilst charging (green light on charger) and the voltages are as follows :

Pin 1 - ground
Pin 2 - 3.4v
Pin 3 - 6.79v
Pin 4 - 6.90v
Pin 5 - 10.37v
Pin 6 - 13.85v
Pin 7 - 14.13v
Pin 8 - 14.14v
Pin 9 - 14.13v
Pin 10 - 14.3v
Pin 11 - 14.3v
Pin 12 - 40.8v
Pin 13 - 41.9v

The blown area on the bms has been cleaned and I have probed the pads and found 42v on one pad which has continuity with the dc input, However I do get 42v direct to the battery when charger is connected so you are probably correct in the blown component is unrelated

I have also tested all of the larger components on the board and all are working ok.
Craig.
Welcome to the discussion and thank you for the contribution, look forward to seeing you soon at the repair shack.
Bryan
 
D

Deleted member 4366

Guest
Something very strange going on. The wires are the sense wires on each of the 10 cell groups. If the total is 41.9v, the 10 cell groups should go up in increments of 4.2v, apart fom the two not connected. Pull the connector out and check the voltages on the slots on the side. Maybe it's not making good contact.Try pulling it on and off a few times to see if the battery comes back to life.

Did you check that your voltmeter is working properly and the battery in it isn't down?

You shouldn't check them with the charger on. Maybe the PWM was upsetting your meter.
 
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craigp

Just Joined
Apr 18, 2016
4
2
40
Something very strange going on. The wires are the sense wires on each of the 10 cell groups. If the total is 41.9v, the 10 cell groups should go up in increments of 4.2v, apart fom the two not connected. Pull the connector out and check the voltages on the slots on the side. Maybe it's not making good contact.Try pulling it on and off a few times to see if the battery comes back to life.

Did you check that your voltmeter is working properly and the battery in it isn't down?

You shouldn't check them with the charger on. Maybe the PWM was upsetting your meter.
I have just rechecked with the connector disconnected by probing the pins on the connector and also at the tabs on the battery and they are all correct. yes my multi meter is working correctly.

And have also tested with the charger disconnected now with the same result.
with the charger disconnected the 42v that is at the main battery terminals drops down rapidly to 11v and the individual cell voltages slowly go down aswell
 
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