PLEASE HELP --- BATTERY PROBLEM

[gzmann]

I am having a problem with a Chinese made/sent battery that I have had no problems with unitl a few days ago. It is a 16S 48v 20ah battery with a bms. It came with a 3a charger. I have it on a converted mountain bike with a geared motor. I have been using and charging this battery without any problems for a couple months. Suddenly after using it for 20 minutes after a full charge it just stopped working in the middle of my ride. ( I can normally go 60 min without any problems) I peddled home, put the battery on charger and it WOULD NOT charge. I hooked it up to another similar electric bike and it would not run the motor either. When I hook it up and put on the electric headlight, the light just flashes rapidly.

I brought the battery to an electric bike shop and they told me they only deal with Bionix bikes and can not help me out.

Can anyone help me out???

I have put a lot of money in this bike setup and I am afraid I am going to have to leave this bike to the side as I can not afford another battery.

 

[dnmun]

do you have a voltmeter or wattmeter and know how to do stuff?

if you took it to a bike shop i kinda assume you are not used to repairing stuff on your own and have no tools or expertise.

i find most people just drop off their threads when presented with the need to examine the behavior or measure stuff.

but batteries are generally easy to repair. controllers are hard. motors almost impossible.

 

[gzmann]

Hello
I do repair a lot of things and have some equipment like voltmeters etc.
I am just not sure where to start??
Why does the battery become inoperable??
I tried to bypass the bms and run the battery directly to the motor but still no benefit?? I assume this is the controller's fault??
The battery voltage read 54v so why isnt it working??

Perhaps I need a little more education about where to start??

Gordon

 

[Amon]

Hello Gzmann/Gordon,

that sounds, judging from my experience, like a broken BMS or drifting/undervolted cells.

The most "standard" asian BMS and batterys are "fine for some months" on normal discarge speeds (means: low discarge ampere rate). But after this they tend to drift more than the BMS can balance, get fat (build up gas inside), go overvoltage or undervoltage and are "balanced to death" if you let it rest with an (probably always attached) BMS as alot of those asian BMS tend to balance all cells to match the lowest one - so if this one is defective.. you can guess the remaining story.

If I were you, I would open up the battery pack (maybe you selected no flat bag cell type but screwed cells like Headways?) and check for visible signs of deceased cells. If they all look fine, I would measure the voltage of all single cells (no need to detach them) with the Voltmeter/multimeter.

The main problem about those "manufactured packs" is the combination of an dumb charger (more like a plug-powersupply) and cheap BMS. Some people tend to leave them idling for a while and because of some more drifting / self discarging cells they "ruin themself" then (the BMS does).

But the only person which can look behind the shrinking tube is you.. and if you had any warranty on the pack or something like this, I would prefer to try to contact the shop and hope the best.

Best regards,
Amon

 

[Amon]

Forgot something:

Ah, 54V on 16 S would be around 3,375V each pack, if the controller takes a high ampere spike on power-on, this might result in a voltage drop too high to maintain function.

Are those LiPo/LiIon or LiFePO4/LiFeYPO4?

Best regards
Amon

 

[dnmun]

if your battery has no conduction when you bypass the BMS and connect directly to B+ and B- then there is an open circuit in the battery if you see no voltage.

 

[999zip999]

Where did this battery come from ? Maybe a pic.
So the battery dosn't work straight from the battery no bms just battery pos. and the neg. termanial

 

[gzmann]

I got the battery from china
the battery worked well until one day while using it, it suddenly gave no power ( no event to start it off)
the battery gave no power to the electric motor but did power the headlight i have on the bike-- even then all the light did was flicker rapidly??????? not sure why that is the case.

I will open up the shrink wrap and see what is wrong.

Thanks for the comments!!!!

Gordon

 

[dnmun]

you do not have to open the shrink wrap. post up a a picture of your battery and the BMS so we can see it close up on both sides.