tucker74
100 µW
I have had it on charge for an hour and still battery is dead can anyone help please 
Why is my polaris battery doing this when i plug charger in.
- Thread starter tucker74
- Start date
tucker74
100 µW
Yes it is green until I plug it into battery.
Your battery could be damaged and the BMS is keeping it from being charged to prevent further damage. Can you provide more details like how old it is and how many charge cycles it’s had? Has it been in storage? Any recent degradation in performance, or anything unusual happen the last time you used it?
tucker74
100 µW
It has been in storage for nearly 8 years . My friend used it 4 times from new then stored it as he replaced with motor bike. So I have taken the battery to charge it and it is just doing . I have only charged it for an hour because I don't want to damage it anymore. It was fine when he put it away.
RunForTheHills
1 kW
You can't store a battery for eight years without maintaining it. Most likely the battery management system is preventing you from charging the battery because the cells have dropped below the low voltage cutoff due to self discharging for eight years. You should buy a new battery.
Wow. See above.
tucker74
100 µW
Thank you I will look into finding a new one on Internet.
2Phast2Delirious
100 W
- Joined
- Mar 16, 2022
- Messages
- 105
Did you check the voltage before and after charging for an hour?
I've personally bought an old supply of new lithium e-bike batteries and spent eight hours on charging it, checking the voltage with a meter every 30 to 60 minutes. I bought them intending to disassemble for the cells, but since I was able to bring them back to life, I decided to leave it exactly as it was.
Before placing it on the charger, I do recall connecting some of the batteries in parallel with a good one (1-5min) to allow for a quicker revive because the voltage were too low to charge via BMS.
I've personally bought an old supply of new lithium e-bike batteries and spent eight hours on charging it, checking the voltage with a meter every 30 to 60 minutes. I bought them intending to disassemble for the cells, but since I was able to bring them back to life, I decided to leave it exactly as it was.
Before placing it on the charger, I do recall connecting some of the batteries in parallel with a good one (1-5min) to allow for a quicker revive because the voltage were too low to charge via BMS.
Last edited:
tucker74
100 µW
What do you mean parallel with a good battery. Does that mean connect batteries together + to + and - to - before charging?
jetpackjbd
100 W
Yep, exactly. You can bypass the charger that way, which isn’t recommended but can be done to revive batteries that are too low of voltage for your charger to recognize. Can be a bit of a fire hazard as you’re charging a questionable battery at like 30 amps, but the BMS should hopefully do something to prevent a fire. Maybe.
Sometimes it’s the BMS that won’t let you charge the battery because of low voltage, not just the charger, in which case connecting the battery to another battery won’t do anything. The only way to bypass the BMS in a pack like this would be to disassemble the pack and charge the cells directly, but that’s even more of a fire hazard.
I’d suggest just buying a new pack or finding someone to rebuild your existing pack if you can’t buy a new one anymore.
2Phast2Delirious
100 W
- Joined
- Mar 16, 2022
- Messages
- 105
any working battery that is fully charged and has the same voltage.
Correct. After monitoring and charging it for one to five minutes in parallel, disconnect the batteries from parallel and put it back on the charger to see whether it will charge further.
Please do some research on this method and do it at your own risk as it may be unsafe.
Last edited:
tucker74
100 µW
I will look into to that thank you.
The BMS should *already* have done something, if the charger itself won't charge it because it's too low it should mean the BMS has turned it's output off. If it hasn't, or can't, then connecting an essentially unlimited current source to the pack could set the cells, wiring, BMS itself, etc on fire.
If a fire doesn't occur now, it can still have damaged the cells in a way that could lead to a fire at any moment anytime in the future, and you cannot know if this has happened.
The BMS FETs could also be damaged from the current, and in such a way as to leave the BMS unable to ever disconnect the pack from the charger (or load, in the case of single-port BMS). When that happens, then the cells are completely unprotected; no matter what limit they exceed, the BMS can do nothing about it. And unless you test the BMS to verify it still correctly functions, and that the FETs still perform exactly as their spec sheet says they should, you won't know this has happened either, and will still be expecting the BMS to protect your cells, which it isn't doing...so any form of damage can happen to the cells at any time from any excursion outside their limits, and you won't know that's happened either.
At least, not until that funny smell starts.... :/
Keep in mind that the entire reason the pack won't charge in those situations is because the safety mechanisms built into it have found a problem with the cells that has been determined to be unsafe to recharge.
You may never have a problem with a cell that has had an excursion outside it's limits, or you could have a fire in the next few minutes with it.
The problem is that you cannot know if such damage has occured, and you cannot predict it's future behavior except that the likelihood of a catastrophic failure increases with usage and time.
That's the whole reason these things *have* the protection devices.
If you're not going to "listen" to them, you might as well just take them out entirely and run the cells bare. :/
Last edited:
tucker74
100 µW
Thank you I didn't try that anyway as I didn't fancy blowing myself up .
So is this battery scrap now?
So is this battery scrap now?
I think, someone with a bit of experience, could take this battery apart and measure the voltage of every section. Probably after 8 years most of the cells have self-discharged. By charging each section separately there's a chance to bring it back to life, or determine if the cells are dead for good.
PS i dont recommend connecting with another battery in parallel - usually you don't fix electronics with a hammer.
PS i dont recommend connecting with another battery in parallel - usually you don't fix electronics with a hammer.
Last edited:
