Lifepo4 fully discharged

[newbbike]

Hi guys

I have been given a spare battery pack for my bike which is lifepo4, the lady that gave it to me said it is no use and won't charge. Now it is marked as a 48V 10ah pack and when I plug her charger into it, it does refuse to charge it. But I'm fairly sure that I read something a while ago about this and that I can boost charge it with some other 48v supply as it is only the charger that refuses to charge a flat lifepo4....is this right? Or should I be forgetting it and taking it to a battery recycle point?!

 

[banbury frank]

Hi I would suspect a faulty BMS battery management

you need to open the pack find the 48 volts before the BMS and see if there is any voltage if so charge direct without the BMS then you can buy a new BMS is a small circuit board

LiFePO4 Bleeding Balancing BMS for 16 Cells in Series - BMSBATTERY

it has 3 or maybe 2 connections for the negative + 16 connection for each cell

it will come with diagram

Frank

 

[aaannndddyyy]

Hi guys

I have been given a spare battery pack for my bike which is lifepo4, the lady that gave it to me said it is no use and won't charge. Now it is marked as a 48V 10ah pack and when I plug her charger into it, it does refuse to charge it. But I'm fairly sure that I read something a while ago about this and that I can boost charge it with some other 48v supply as it is only the charger that refuses to charge a flat lifepo4....is this right? Or should I be forgetting it and taking it to a battery recycle point?!

Charger
Dose the lights light up on the charger.
check the plug for a loose wire or blown fuse.
Is there a voltage at the outlet point of the charger close to 60v.
check the out put connector for a loose wire.
check the fuse inside the charger

Battery
check the voltage with a volt meter
check the fuse
check for a loose wires

As banbury frank says in the post below.
Also un-plug the plug from the socket before checking for loose wires. Dont do these checks well your in the bath or outside in the rain, all work done at your own risk and use your common sence.

If all this checks out take reading of voltages and report back for other options.

 

[banbury frank]

DONT open the charger if it is a switch mode type the can be 1.000 volts inside It can kill

Frank

 

[newbbike]

Thanks for the advice guys, I will have a test tomorrow....

The charger is fine it charges my battery no problem, the dud battery pack is identical to mine, when it is plugged into the charger it momentarily shows a charging light then switches to charged and gives no more output. She said she had run it right down when she left the lights etc running for 3 days and then this problem started.

She's already bought a replacement, it'd be great if I can get this one up and running as a spare for mine! I'll check voltages etc tomorrow, open the pack and report back....

 

[newbbike]

OK, so i opened it up today to reveal the guts......

It only measures 12.3 across the series cells, can I add a 48VDC supply across these points to put some charge back in before connecting the normal charger? Not that i've got a 48V supply however! I can perhaps do this in banks of 12v but would i need to disconnect the cells first to do this? Or am i barking up the wrong tree?


Also the output from the charger is 63.2V


Cheers

 

[banbury frank]

Just connect the normal charger onto the heavy black and red wires on the battery making sure you get the polarity rite

The
Bms only balances out the cells

charging without it wont hurt for one charge then you can measure each cell

if that works you need new BMS

Frank

 

[newbbike]

Thanks frank, trying it now....

 

[newbbike]

Now connected, voltage dropped to 6V and is steadily rising....

 

[aaannndddyyy]

Now connected, voltage dropped to 6V and is steadily rising....

IT might be a good idea to take it up to LVC 42.5 with direct charging then try charging though BMS ,if there are any dead cells you may overcharge with direct charging.

 

[newbbike]

I was thinking that it might be best not to take it too close to 48V, it's currently at 27.1V

 

[newbbike]

OK, so a couple of seconds after the last post it shot up to 40.1V and the charger light turned red to indicate it was charging, so i've disconnected the makeshift wires I had connected from the charger to the batt and reconnected the BMS and plugged the charger in the normal socket....so far so good!!

 

[banbury frank]

Hi
once charged you will need to run down and recharge 4 to 6 times to allow the BMS to do its job and balance the cells all the cells should read the same voltage

Frank

 

[newbbike]

OK, cheers....how do i run it down, just use it normally on the bike?

This forum is great! Thanks a million for the advice guys, very much appreciated.

 

[aaannndddyyy]

OK, cheers....how do i run it down, just use it normally on the bike?

This forum is great! Thanks a million for the advice guys, very much appreciated.

With this type of battery lifepo4 running it around the block just to get rid of the service charge will be enough a couple of time as its not a new battery, then leave it on the charger for 12 to 24 hours and keep an eye on it.

 

[banbury frank]

Hi Anybody want to Know how a BMS works well this is probably the Bleeding type

it is wired across the positive terminal on each cell or bunch off cells
so if you look on a 48 volt pack 16 on 36 volt 12

they must be connected in the right order or the BMS will catch fire

some battery packs use very small cells and put them in multiples to make 3.2 volt but higher amp hours ( Capacity Range )

The battery cells are charged at 3.6 volt max

the BMS has a resistor to dump the over voltage on lifepo4 this is 3.2 volts this is switches in and out by a transistor so you will get some heat on the BMS board so don't worry that is normal it will only be some off the resistors that get hot

the whole pack is about 52 volts but called 48
same with 60 volt it is about 66 volt but called 60 volt

This is different on Lithium - ion higher voltage less cells

I build high power lifepo4 battery's 48 volt and 60 volt with 80 amp BMS rated continuous 80 amps peak 20 seconds at 160 amps

Frank

 

[stevebills]

The external battery is 36v 20ah li-ion frank and how long do I leave it charging and wil it be safe to go bed while its on?

 

[banbury frank]

Hi Steve as long as you use the right charger it is OK It will cut off when it reaches about 42 volts the BMS balances out the cells so they are the same voltage the bms may work again once you get some charge in the battery

so Plug and Go

Frank

 

[stevebills]

Hi Steve as long as you use the right charger it is OK It will cut off when it reaches about 42 volts the BMS balances out the cells so they are the same voltage the bms may work again once you get some charge in the battery

so Plug and Go

Frank

I hope it works and I nearly throw this battery away last week and was about to order a ping cheers Frank

 

[newbbike]

I'd just like to say thanks to the guys that gave me input and support in fixing the battery pack! It is up and running and now I have a free spare pack for my bike which has saved me a chunk of money, not that I would have spent it anyway but it is a bonus!!

Cheers