LifePo4 not charging well.

[Range]

One of 4 of my batteries does not charge beyond 3.37v while d next to it is about 3.45v the last 2 are over charged to about 3.6 n 3.7 respectively. Overall charge on meter is 14.2v full charge. I make use of heltec bms. However, during usage/discharge,each battery reads same voltage for all 4 i.e about 3.31v or there about.How do I fix this pls? Battery is lishen 105amp, 3.2v.

 

[mrzed001]

One of 4 of my batteries does not charge beyond 3.37v while d next to it is about 3.45v the last 2 are over charged to about 3.6 n 3.7 respectively. Overall charge on meter is 14.2v full charge. I make use of heltec bms. However, during usage/discharge,each battery reads same voltage for all 4 i.e about 3.31v or there about.How do I fix this pls? Battery is lishen 105amp, 3.2v.

Did you do a proper top balance?
It seems your cells are not on the same SoC.
On a long run Heltec can bring all closer, but nothing is better than top balance

 

[TomC4306]

+1.
Disassemble, connect in parallel, apply bench power supply at 3.5v until current drops to zero.
Reassemble in series
Problem fixed.

 

[Range]

It was top balanced when a friend delivered it to me and everything seems fine. It all started when a terminal of one battery worned out so there was no firm grip.Now, d terminal is fully fixed now and grip if super.

 

[TomC4306]

With the voltages you reported in your first post, everything is NOT fine.
These cells need a new top balance.

 

[mrzed001]

It was top balanced when a friend delivered it to me and everything seems fine. It all started when a terminal of one battery worned out so there was no firm grip.Now, d terminal is fully fixed now and grip if super.

That seems to be a bad connection on the terminal. Did no good to the cell but if cell not bloated then OK
Try the top balance first

 

[Range]

+1.
Disassemble, connect in parallel, apply bench power supply at 3.5v until current drops to zero.
Reassemble in series
Problem fixed.

I dont have a bench charger. A big culprit.
I only v 12v charger.

 

[Range]

Still charging right now 13.5v
3 cells 3.37
1 cell 3.36

 

[TomC4306]

I dont have a bench charger. A big culprit.
I only v 12v charger.

Buy one.
If you can afford to buy the cells and the bms, and the scc, and the inverter, you can afford the $50-60 for a critical piece of test equipment.

 

[mikefitz]

When you battery is charging and the cell voltages of the high cell starts to increase above the other cells, apply a load across the cell for several seconds, use a 12v car headlamp bulb, whilst measuring the cell volts. Repeat with the high cell as necessary.

Alternatively accept you are loosing a small % of capacity and charge to 13.8 or 14 volts.

Mike

 

[MisterSandals]

Alternatively accept you are loosing a small % of capacity and charge to 13.8 or 14 volts.

+1 ^^^This^^^

And, your Heltec hopefully will get things more balanced at the high end of charge. Then, should you find you need the last 1% of capacity, you can charge higher.

 

[Range]

When you battery is charging and the cell voltages of the high cell starts to increase above the other cells, apply a load across the cell for several seconds, use a 12v car headlamp bulb, whilst measuring the cell volts. Repeat with the high cell as necessary.

Alternatively accept you are loosing a small % of capacity and charge to 13.8 or 14 volts.

Mike

Thanks Mike

But the discharge will decrease all cells.
Really wish I have a 3v device

 

[MisterSandals]

But the discharge will decrease all cells.

Not if you connect it to only the cell you want to discharge. Which I am pretty sure is what Mike implied.

 

[Range]

Not if you connect it to only the cell you want to discharge. Which I am pretty sure is what Mike implied.

Each cell is 3.2v
Car lamp is 12v

 

[Texas-Mark]

Each cell is 3.2v
Car lamp is 12v

Does not matter, you are only applying a load to drain off a bit of the charge on the high cell.

 

[Range]

Does not matter, you are only applying a load to drain off a bit of the charge on the high cell.

Is it same as connecting to an inverter and discharge with loads?

 

[mikefitz]

You are using the current flow through the resistance of the bulb to dissipate energy from the selected cell and lower its capacity slightly. Could could use any suitable resistor.
A headlight bulb is readily obtainable and the fact it ' lights up' ( even on 3 volts) is a useful indication you have made contact.
With a little practice you can judge how long you need to make contact for the necessary volt drop. It needs only seconds, typically 1 to 10 seconds of contact to make a measurable difference.
It sounds a somewhat crazy idea, but it does work.

Mike

 

[Texas-Mark]

Is it same as connecting to an inverter and discharge with loads?

Not really. With the bulb, you are targeting an individual cell to do a makeshift balance. Using the inverter as a load will load down all cells at the same rate (more or less).

 

[DerpsyDoodler]

One of 4 of my batteries does not charge beyond 3.37v while d next to it is about 3.45v the last 2 are over charged to about 3.6 n 3.7 respectively. Overall charge on meter is 14.2v full charge. I make use of heltec bms. However, during usage/discharge,each battery reads same voltage for all 4 i.e about 3.31v or there about.How do I fix this pls? Battery is lishen 105amp, 3.2v.

I know I am coming in late, but it looks like there wasn't enough attention paid to making sure the terminals, lugs, and bus bars are good and clean. Based on what you've said, it does look like you need a top balance, but I would bet money that you also need to properly clean the terminals, lugs, and bus bars with fine grit sandpaper and isopropyl alcohol. also apply some oxguard or noalox during reassembly.

 

[Range]

You are using the current flow through the resistance of the bulb to dissipate energy from the selected cell and lower its capacity slightly. Could could use any suitable resistor.
A headlight bulb is readily obtainable and the fact it ' lights up' ( even on 3 volts) is a useful indication you have made contact.
With a little practice you can judge how long you need to make contact for the necessary volt drop. It needs only seconds, typically 1 to 10 seconds of contact to make a measurable difference.
It sounds a somewhat crazy idea, but it does work.

Mike

Wow!!!
Will try it out and get back to you.

 

[Range]

I know I am coming in late, but it looks like there wasn't enough attention paid to making sure the terminals, lugs, and bus bars are good and clean. Based on what you've said, it does look like you need a top balance, but I would bet money that you also need to properly clean the terminals, lugs, and bus bars with fine grit sandpaper and isopropyl alcohol. also apply some oxguard or noalox during reassembly.

Bus bars, terminals, lugs are still fesh. Will check if discharging the high cells fail.

 

[DerpsyDoodler]

Bus bars, terminals, lugs are still fesh. Will check if discharging the high cells fail.

Aluminum terminals will immediately begin to accumulate a layer of oxidation. If you didnt scuff them before assembly, then you need to. and since you're taking them apart, you'll likely need to do the same to the lugs. At the very least clean them and the bus bar(s) with isopropyl.

 

[Range]

Aluminum terminals will immediately begin to accumulate a layer of oxidation. If you didnt scuff them before assembly, then you need to. and since you're taking them apart, you'll likely need to do the same to the lugs. At the very least clean them and the bus bar(s) with isopropyl.

Ok thanks a lot
Thanks to everyone who replied.

 

[Range]

Wow!!!
Will try it out and get back to you.

Higher cells discharged by the bulb worked.
Thanks Mike. Will still update u as it unfolds.

 

[Alkaline]

Easier way:

Add a active balancer, wait 2 days. Should all be about the same voltage.