I have a 52 volt 24 ah triangular battery that I purchased from Luna along with a BBSHD motor that i installed on a Jamis Durango II last spring and have been enjoying it to commute 50 miles to work and back for several months until it suddenly left me stranded at work on two occasions acting as though the battery was dead....only to find out later the battery was not dead, but was simply asleep and shut down. Three times now the battery seems to go to sleep when I set the charger to charge to 100% and it is apparently getting an overcharged cell and waiting to bleed down the voltage before I can use it. I have been able to jump start the battery the first time by just plugging it into the charger later hours after the shutdown and it sprang to life as though nothing was wrong. I have two chargers and have had it happen with both chargers when set to 100%. Unlikely the chargers are bad I am hoping it is only a setting in the BMS or at worst the BMS needs to be changed. Any input would be greatly appreciated until I hear back from LUNA I am not using the bike, as it is very cold and bad weather here in Maine I cannot chance on getting stranded by a sleeping battery. There is a small volt meter plugged into the pack that will let me know if the battery is awake or not so today it is asleep after getting charged up last night and I drove the E Car (Honda Clarity hybrid) to work instead. I will call home to have the better half check to see if it wakes up on its own or if it will need to be jump started. I could always only charge to 90% which will in the long term only increase the amount of charge cycles, but I only have one smart charger and will need a second unless I am going to babysit the battery while charging on the basic charger as I have the volt meter it is doable but the 2 times I let it go to 100% I got stranded so not a good plan as pedaling a 65 pound bicycle 25 miles with no help from the motor is more of a workout than I want!
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52 volt 24 ah battery playing possum
- Thread starter patdown45
- Start date
dogman dan
1 PW
One thing might be going on here. Your battery might be going too full and sleeping because its badly out of balance. A bms can only do so much per cycle, and it could be that the thing just needs more balancing to return to more normal.
Can you measure the voltage of each cell at the bms? Doing that while it is asleep after a charge would help both us, and Luna CS diagnose this.
The way I advise forcing a bms equipped battery to balance is charge full, let sit 30 min for the bms to work, then ride around the block to discharge just slightly. Repeat about 10 times, till the pack starts to hold its full voltage whatever it is. This won't work unless you charge full, so the sleeping might make this hard to do.
In other words, each cycle of this the whole pack keeps creeping up in full voltage after the charge and 30 min wait. So if 58v full is normal, an unbalanced pack would be less, say 56v. Then a few cycles of this force balance and you get it to hold at 57v. When it won't climb any more, its as balanced as it gets. Bear in mind, a new pack can hold full voltage, but as it ages this drops. It really drops when a cell fails in the pack, but older cells will charge to 4.2v, but then self discharge back to 4.18, or 5.15 as they get older and older. But if one cell group is losing its capacity a bit more than the others, it will fill first, and the rest get an undercharge. Then this keeps going that way till the pack is severely out of balance.
If you have access to the bms wires, and the battery warranty period is over, then it might be possible to locate the highest charge cell group, then rig up a way to discharge it some. I have done this with two wires soldered to a car turn signal light bulb. Somehow connect the bulb to the highest charge cell group, and lower it to same as the others. Then put it back on the charger with the bms plugged back in.
Can you measure the voltage of each cell at the bms? Doing that while it is asleep after a charge would help both us, and Luna CS diagnose this.
The way I advise forcing a bms equipped battery to balance is charge full, let sit 30 min for the bms to work, then ride around the block to discharge just slightly. Repeat about 10 times, till the pack starts to hold its full voltage whatever it is. This won't work unless you charge full, so the sleeping might make this hard to do.
In other words, each cycle of this the whole pack keeps creeping up in full voltage after the charge and 30 min wait. So if 58v full is normal, an unbalanced pack would be less, say 56v. Then a few cycles of this force balance and you get it to hold at 57v. When it won't climb any more, its as balanced as it gets. Bear in mind, a new pack can hold full voltage, but as it ages this drops. It really drops when a cell fails in the pack, but older cells will charge to 4.2v, but then self discharge back to 4.18, or 5.15 as they get older and older. But if one cell group is losing its capacity a bit more than the others, it will fill first, and the rest get an undercharge. Then this keeps going that way till the pack is severely out of balance.
If you have access to the bms wires, and the battery warranty period is over, then it might be possible to locate the highest charge cell group, then rig up a way to discharge it some. I have done this with two wires soldered to a car turn signal light bulb. Somehow connect the bulb to the highest charge cell group, and lower it to same as the others. Then put it back on the charger with the bms plugged back in.
Thanks for the information, I have done a couple experiments since and found if I charge to 90% it is fine. Then I put it on 100% charge to see if I can watch the battery go to sleep, but saw the voltage go to 59.1 volts and decided to not proceed as that is higher than the charger is supposed to go. I will retry with the battery and charger in my basement in the wood stove incase it has a runaway cell. I don't want to open up the pack until I get some shrink wrap to replace what I have on it now, but I think it is apparent that I am going to have to. Thinking about changing the BBSHD Stock controller with the 800 asi external controller that will allow more speed and current with my 52 volt battery. I will keep posting with updates
Do NOT use that charger then, easy to burn the house down.patdown45 said:
Your BMS is doing its job, be grateful, many don't.
Put in another HVC layer of protection IMO.
And there are dedicated balancers that will do the job much faster and better, and without requiring you let the pack sit at too high V for too long, which harms longevity.
999zip999
100 TW
I more powerful controller can be to hard on your battery. How old is the battery. the charger should not go that high do you have a good battery In your meter ? The bms should kick in and bleed down the high battery charge if at not to high of charge rate ? But should never use a charger set to high and hope the bms can keep up with those little bleed resistors on most bms. Never over charge a cell.
I closely monitored the charge and it did never again go up past 58.6 and it also didn't go back to sleep so somehow I think it is balanced but I'm going to try the 10 quick run down a little bit charge it up Cycles to make sure it does seem odd that that Luna charger would even allow it to go up to 59 volts but that's what was reading on the little display that came with the battery I would double check that with a voltmeter the next time I see it but I just didn't want to take a chance I don't believe they're Chargers defective although it could be I closely monitor the charge and it didn't ever again go up past 58.6 and it also didn't go back to sleep so somehow I think it is balanced but I'm going to try the 10 quick run down a little bit charge it up Cycles to make sure it does seem odd that that Luna charger would even allow it to go up to 59 volts but that's what was reading on the little display that came with the battery I would double check that with a voltmeter the next time I see it but I just didn't want to take a chance I don't believe the charger is defective although it could be I will put a meter on it the next time it's charging to see how much is putting out. Just now it is showing 1.1 volt higher than my meter. The little meter that Luna supplied is plugged into the pack from Luna, I am not sure where. I just checked the charger output while charging with another meter at the xt60 charger connection I got 50 volts while the little meter from Luna was showing 51.1 so I think that meter from Luna is off. Hopefully things are all good now
I've concluded all the testing on the 52 volt battery and determine the BMS is defective after opening up the battery pack I discovered 2 of the balance wires was no longer connected and I re connected (soldered) them back on but the battery is still asleep and not showing voltage at the volt meter that Luna supplied. I've done voltage checks across each of the cells and they all are showing between 4.1 and 4.0 however in the 9th cell at the wire connection at the bms I discovered 0.0 voltage when the harness is connected to the BMS, however when I unplugged the connector and checked the voltage was 4.1 and 4.0 between all the cells and in series they went from 4.1 to 58.1
however when checking each of the cells at the balance lead connections where they are soldered to the battery it appeared to get correct voltages so the voltages I got at each of the series was 4.1, 8.2, 12.4, 16.5, 20.7, 24.9, 29.0, 33.2, 37.3, 41.5, 45.7, 49.8, 54.0 + 58.1. Reconnecting the balance wires has not helped and it is not waking up. Hopefully the replacement BMS will fix this. I have hand drawn out the placement on the pack and cannot find 1 of these balance wires the 58.1 the 14th ?
Sent from Samsung tablet.
however when checking each of the cells at the balance lead connections where they are soldered to the battery it appeared to get correct voltages so the voltages I got at each of the series was 4.1, 8.2, 12.4, 16.5, 20.7, 24.9, 29.0, 33.2, 37.3, 41.5, 45.7, 49.8, 54.0 + 58.1. Reconnecting the balance wires has not helped and it is not waking up. Hopefully the replacement BMS will fix this. I have hand drawn out the placement on the pack and cannot find 1 of these balance wires the 58.1 the 14th ?
Sent from Samsung tablet.
However you build it, leave access to the cell-group balance leads and the BMS easily replaceable.
Capacity test each old cell before combining with new, maybe resistance as well.
Best to break up those walls of text, new topics get their own threads, or e.g. join a Vruzend thread if you don't want to start a new one.
Capacity test each old cell before combining with new, maybe resistance as well.
Best to break up those walls of text, new topics get their own threads, or e.g. join a Vruzend thread if you don't want to start a new one.
999zip999
100 TW
Bms? Love or hate.. had one kill a cell group on my ping battery. How old is this battery ?
