48 volt, 15 a*h, 18650 Calibike battery blacks out

[bigoilbob]

I have over 100 recharge cycles, and over 80 hours on this battery, with no problems until this week. Random blackouts. The on/off switch is fine. Service is restored by either plugging into the charger, or cycling the on/off switch. But only for a minute or 2. The problem SEEMS less frequent with very low amp draw, but I never draw more than 14-1 amps. Well below rating. Calibike (Rafe) is communicating, but SLOWLY. I think it's my BMS, which (1) Just seems to plug in, (2) Is cheap, (3) Could be properly chosen and sent by Calibike.

Any alternative ideas on my problem? If I could choose the right BMS, I would be happy to send for it. Anyone know the right BMS for my battery?

Thx in advance..

 

[Icewrench]

Sounds like the bms is shutting off.
Might be a problem with the bms.
Or it might be that the battery is out of balance.
Is there a weak cell group in the battery?

 

[Hwy89]

Like Icewrench said, it is most likely that the battery is severely out of balance and the BMS is shutting it down. Can you open it up and take voltage readings on each of the cell groups? If you can just access the BMS board you could measure at the pins where the balance wires plug into the board. Post a photo and someone here will tell you where to measure. Just be very careful not to bridge two pins with your meter probe.

 

[2old]

Agree with the above as this occurred with two 36V, 10 a/h dolphin batteries. Removed the pack from one and didn't see anything wrong except some no-name Chinese junk batteries. Just chucked it rather than take a chance. The second is ready for the same fate. Don't recommend this to everyone, but I like to sleep soundly at night.

 

[amberwolf]

There are a few calibike battery pack troubleshooting threads here on ES; some show in this search
https://endless-sphere.com/forums/search.php?keywords=calibike&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

one says that the bms doesn't have a balancing function on the pack he got, but that other packs do have them. So if yours doens't have a balancer, then your cells could be at varying voltages, states of charge, and the bms can't do anything about it.


When they are very different soc, then when you try to pull a significant current some of them drop below the LVC in the BMS, even though others are fully charged.

If there is a balancer on the bms, leaving the pack on the charger for days, or weeks, would eventually fix it if it's all working like it should.

But if it's not, or has no balancer, you'd have to manually drain the high cells or fill up the low ones.


If you look around at the various other battery troubleshooting threads, many of them show how to do this.

 

[bigoilbob]

There are a few calibike battery pack troubleshooting threads here on ES; some show in this search
https://endless-sphere.com/forums/search.php?keywords=calibike&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

one says that the bms doesn't have a balancing function on the pack he got, but that other packs do have them. So if yours doens't have a balancer, then your cells could be at varying voltages, states of charge, and the bms can't do anything about it.


When they are very different soc, then when you try to pull a significant current some of them drop below the LVC in the BMS, even though others are fully charged.

If there is a balancer on the bms, leaving the pack on the charger for days, or weeks, would eventually fix it if it's all working like it should.

But if it's not, or has no balancer, you'd have to manually drain the high cells or fill up the low ones.


If you look around at the various other battery troubleshooting threads, many of them show how to do this.

Thx amberwolf - and all of you. If I had to guess, it would be your contention that I'm dropping blow LVC, and don't even see it on my controller B4 blacking out. As for all of the checking by other posters, I know you mean well, but I paid many hundred bux to avoid being in the battery diagnosis biz.

Rafe has quoted me a new BMS, but also asked for a pic of my current one. I asked for a quote on a new one based on the hope that he knew exactly what he sold me ~1-1/2 years ago. I'll cut my cardboard and send him that pic, but I wish that he had a firm idea what he has been interselling......

 

[bigoilbob]

Agree with the above as this occurred with two 36V, 10 a/h dolphin batteries. Removed the pack from one and didn't see anything wrong except some no-name Chinese junk batteries. Just chucked it rather than take a chance. The second is ready for the same fate. Don't recommend this to everyone, but I like to sleep soundly at night.

Special thx to you for not sparing me on what might indeed be the case. But I'm gonna chase my possibly/probably badly spent $'s with a few pennies on the hope of recovering my battery. Specifically, ~$36 for a new BMS to get service from my $550 battery back.

 

[dustNbone]

I'd check the cell group voltages first before investing time and money in replacing the BMS. Keep in mind that it's probably not cutting out on low pack voltage but rather low voltage on one set of cells. The readout on your display won't reflect this. If that's the case the BMS is working as it's supposed to, and replacing it will result in the same problem. Check the voltages after it cuts off, there's a good chance you will find one group is substantially lower than the remainder. The test costs nothing but a bit of time.

 

[Hwy89]

Being in the "battery diagnosing biz" may be beneath your dignity but realize that plugging a new BMS board into a pack with possibly defective cells may not be a cure.
If you do get a replacement, be sure to do as AW suggests and leave it on the charger for a long enough time for the cells to balance. Oh but wait, you don't care to determine if they are balanced or not. So, never mind.

 

[999zip999]

You should write down on paper the cell voltages starting at the neg end. Like this.
1. 3.99v
2. 2.89v
3. 3.89v

13. Xxxx volt
I tape or shrink tube my probes so only a small tip shows this makes it hard to short. Report back.
You should only put a bms on a balance pack. It's just a little baby balancer can't work miracles so balance your pack first before installing new BMS.

 

[amberwolf]

Thx amberwolf - and all of you. If I had to guess, it would be your contention that I'm dropping blow LVC, and don't even see it on my controller B4 blacking out. As for all of the checking by other posters, I know you mean well, but I paid many hundred bux to avoid being in the battery diagnosis biz.

Unfortunately, you've ended up in it anyway, as everyone will eventually, unless they just toss the battery as soon as any problem arises.

You can't see it on your controller becuase it's all inside the battery, and unless you have balance wires that come out of the pack and go up to the handlebars to a device that shows you each cell group's voltage all the time, you cannot see the problem without opening the pack.

Replacing the BMS is almost certainly a waste of money, as it is almost never the BMS at fault in cases like yours--it is almost always a cell group (or groups) that is low compared to the others, or a balance wire that is no longer connected properly (or at all) to a cell group.

Usually when BMS fails, it's the charge or discharge FETs, and then either the pack won't charge at all, or it won't discharge at all...it doesn't usually cut out after working for a moment.

Sometimes a bad BMS may *cause* a cell balance problem, for a number of reasons, but that's not that common either.

Either way, unless you check the individual cell voltages while you have the pack open, you won't see whether or not the cells are the problem. It only takes a few minutes, and it is easy if you look at other threads that show pack testing to show you how (might even be a wiki entry by now); you can even look at my old Vpower / Volgood / CammyCC repair threads for pics and info, if you search my posts for those terms.