Problem hub motor/battery cuts out under heavy load

[ridingmn]

Just to clarify for myself should I continue to drain charge any of the other cells or just keep the charger plugged in. And if I need to drain charge the other 15 cells what is the best way to do that, would I just wire flashlight bulbs to each cell? Sorry for what I'm sure are elementary questions.

 

[ridingmn]

Voltage seems to be dropping back to what it was before 54.7v even though it is still plugged in but I guess the BMS has the charger switched off.

 

[dnmun]

leave it charging all the time. to drain down the other cells you can find a long group that are high and connect the light bulb to each end of that section. working above and below the low cells. so you need a higher voltage bulb for longer sections. 120V AC bulb will work too.

 

[ridingmn]

I have the first 12 cells down to ~3.3v and am working my way down the line. What should I expect when I have them all around the 3.3v's of the lowest cell?

 

[ridingmn]

All cells are ~3.3v so they are closer to each other no obvious out layer, but the over all pack voltage is down to 53.6v inline with the ~3.3v per cell. Will the pack voltage start to climb now? If not any other advice.

 

[ridingmn]

Also I forgot to mention that the BMS has kept the charger off. The light has stayed green meaning for this charger that it is on but not charging.

 

[dnmun]

does your charger stay off and not turn back on? it may have a latching output so it is not set up to balance a pack under the BMS. open the charger and take some pictures so we can look inside if it never turns on red led again after it goes green the first time.

 

[ridingmn]

It does it has not switched back on all afternoon. Here are some photos of the charger.

 

[dnmun]

i don't understand why people do not post their pictures in their thread. i have asked the other guy to post his pictures in his thread and he refuses to do it too.

can you read the part number on that transistor in the lower right corner and what are those blue things with the white goop connected to?

you need to find the right kind of charger. this charger will not balance your pack under the BMS.

i wish the people who sell this stuff knew something about how a battery is balanced under a BMS.

 

[Dave Sloan]

To balance the battery you require a low amp charger. To achieve this add a load using a light bulb or resistor that slows the charging rate down. Most bms load up the cells that are close to charged giving the other cells a chance to catch up. If a charger with greater then 1.5 amps is used the bms cannot discharge the close to charged cells fast enough. By adding the load the time of charging is increased for the low cells. If the charger restarts after the high cell drops in voltage then you are off to the races. Otherwise you will have to use a timer or manually restart. Hopefully it is not the one cell = good luck

 

[ridingmn]

Hi sorry about the photos I'm just learning the forum, I have tried to post these photos in the posting. I was unsure of which transistor you wanted the number, which photo. What would be a good charger to purchase if I can't get this one to work. Thanks for all of the help.

 

[ridingmn]

Sorry it doesn't look like the photos posted in the post, I'll have to read more on the proper way to do it.

 

[dnmun]

that integrated circuit in the lower right corner controls the relay. it is turning the relay off when the voltage or current reaches a set point and i suspect the two trim pots are for setting the voltage and current. maybe only current where the integrated circuit decides it is essentially fully charged and turns off the relay.

 

[ridingmn]

Am I correct to assume that there is not much else I can do other than purchase a charger that will balance charge my battery? Why on earth would Golden Motor sell me a charger with a battery that won't balance charge it, I suppose because I don't know any better and buy it anyway

 

[999zip999]

The bms draining all the high cells the match the lowest cell takes a lot of time. Days on the charger. Running a small lifepo4 10ah till cut off or up steep hills kills small batteries if lugging a motor.

 

[wesnewell]

Unplug the charger from the battery pack. Then unplug it from the wall for 60 seconds. Now plug it back into the wall and then into the battery pack. Is it charging now?

 

[ridingmn]

Unplug the charger from the battery pack. Then unplug it from the wall for 60 seconds. Now plug it back into the wall and then into the battery pack. Is it charging now?

I tried and the charger switched on for 30-40 seconds and then shut off again, now it looks like cell 6 is the high cell, I'm am a little confused.

To balance the battery you require a low amp charger. To achieve this add a load using a light bulb or resistor that slows the charging rate down. Most bms load up the cells that are close to charged giving the other cells a chance to catch up. If a charger with greater then 1.5 amps is used the bms cannot discharge the close to charged cells fast enough. By adding the load the time of charging is increased for the low cells. If the charger restarts after the high cell drops in voltage then you are off to the races. Otherwise you will have to use a timer or manually restart. Hopefully it is not the one cell = good luck

If I try this method do I just hook a flashlight bulb to the main power coming in to the pack before it reaches the BMS? And do I need to drain the pack first.

 

[dnmun]

no, don't do that.

you can solder a wire across the relay and use this charger to see if you can balance the pack.

can you take the circuit board out and take a picture of the underside where the relay is located? see if you can follow the trace from the schottky diodes over to the relay.

that is the positive lead and it is what the relay switches. we can solder a wire on the bottom side to bypass the relay once you find it.

post up your picture here in your thread.

 

[ridingmn]

Here are some pictures of the underside of my charger, it looks unfortunately to be pretty cover up.

 

[ridingmn]

Are there any recommendations for a charger that would work for balancing my battery pack discussed above, I would love to be able to get if functioning properly again? Also is there a safe way to individually charge the low cells up to the high cells to manually balance and if so how would I do that and what charger would I use. Thanks

 

[dnmun]

can you remove that ground plane from underneath? we need to find the spots on the relay to jumper. the only way to do it is underneath i suspect. you can look and see if you can find how to put a jumper around the relay from the top. if we can make this charger stay on it should work yet.

 

[ridingmn]

I will try to remove the grounding plate to see if I can get a photo of the underside of the circuit board, then perhaps there might be a clear view of how to run a jumper wire past the relay. Thanks for all of the help, this is all very much above my pay grade, so I am learning as I go.

 

[ridingmn]

Here are some photos of the underside of the circuit board for my charger. please let me know if you see a way to work around the relay switch. Thanks

 

[999zip999]

You can also look around for a small phone charger at 3.6 volts. Check with meter, don't believe whats printed on the charger, plus check for polarity. So you charge just one low cell. Now you must sit and NOT leave. As that's when it Will overcharge
guaranteed.

 

[ridingmn]

can you remove that ground plane from underneath? we need to find the spots on the relay to jumper. the only way to do it is underneath i suspect. you can look and see if you can find how to put a jumper around the relay from the top. if we can make this charger stay on it should work yet.

Does anyone see a way to run a jumper wire as Dnmun suggested, please let me know. Also if you need a different photo or angle to see also let me know and I can try to provide it.

You can also look around for a small phone charger at 3.6 volts. Check with meter, don't believe whats printed on the charger, plus check for polarity. So you charge just one low cell. Now you must sit and NOT leave. As that's when it Will overcharge
guaranteed.

If I can't get the charger working, I'll try this. I'll start searching for an appropriate 3.6v charger today. Thanks everyone for all of the advise, hopefully I can get my battery working properly soon.