Reviviing LiFeP04 battery

[ozbikeman]

Apologies to those who have already viewed or responded to this. I originally posted in 'E-bike technical', however with only 3 responses I thought that 'Battery Technology' might be more appropriate.

I've got a near new 36V/8AH LiFePO4 pack that has been in storage for a while and has gone flat. As the charge has drained below a certain level, the electronics are now preventing the battery from being charged. I've heard of someone being able to 'jump start' the battery and therefore fool the BMS into accepting a charge - has anyone had experience with this?

Any advice on how I can revive the battery (or at least determine for sure that it is well and truly dead) would be gratefully received.

When measured at the battery socket the voltage is negligible - hardly enough to move the needle. I decided to take the whole battery pack out of the packaging and found that there is 20V+ on the other side of the circuit board. I tried to jumper another 36V battery to the wires and then charge the battery (hoping to fool the controller that there is more than 20V on the other side) but the green light goes on on the charger after about 2 seconds.

2 pictures attached showing the setup as it is now. Would appreciate any insight into how I can get it going. I'm confident that there is life in those cells but the battery won't allow the charger to charge.

 

[commanda]

Partially recharging using a laboratory, or benchtop, power supply would be quite easy. These are the ones with variable voltage & current limit. Typically 0-30 volts & 0-3 amps.

A jury-rigged setup could be fashioned using any sort of dc power supply and a resistor. You can access single or multiple cells by unplugging the balance leads from the bms board on the end.

Let me know what you have in the way of wall warts, and I'll suggest some resistor values you can source from your junk box, or traipse on down to your local Rat-Shack.

You obviously already possess a multimeter.

Looking at your handle, maybe you're in Australia? if so, replace wall-warts with plug-pack, and Rat-Shack with Jaycar or DSE.
If you're in Sydney, bring it over to my place.

Amanda

 

[ozbikeman]

Partially recharging using a laboratory, or benchtop, power supply would be quite easy. These are the ones with variable voltage & current limit. Typically 0-30 volts & 0-3 amps.

A jury-rigged setup could be fashioned using any sort of dc power supply and a resistor. You can access single or multiple cells by unplugging the balance leads from the bms board on the end.

Let me know what you have in the way of wall warts, and I'll suggest some resistor values you can source from your junk box, or traipse on down to your local Rat-Shack.

You obviously already possess a multimeter.

Looking at your handle, maybe you're in Australia? if so, replace wall-warts with plug-pack, and Rat-Shack with Jaycar or DSE.
If you're in Sydney, bring it over to my place.

Amanda

1. Thanks for the advice. I have a similar 36V battery pack I could use as a DC power source. Would apreciate your advice on resistor value to apply.

2. Great detective work! Yes I'm in Sydney. Would love to take you up on the offer - I'm sitting perilously on the edge of my technical ability at the moment!

 

[commanda]

PM sent.