Battery Pack Neglected for 3 years

[Bedmountain]

Hi all
3 years ago I built my own 14s8p battery pack out of Samsung 25R's (with much assistance from Alan (Bikemad))
I rode about 500 miles using this battery and it was a joy to use.
Unfortunately I had a serious accident (not e-bike related) and have had limited physical abilities for a long time.
Having now recovered to a point where I can get on the bike again I'm having a few issues ...
The battery has been sitting connected to a charger all that time with the charger switched off. The charger probably got switched on every few months over that time and when it did get switched on I recall hearing it power up and start charging.
I have a Luna 58.8v 3A charger.
I switched the battery on and could see 56.3V shown on the cycle analyst. Plugged the charger in but nothing happened (charger showing green - fully charged light)
Took the bike out for a spin and straight away it was cutting out under any load. turning battery off and on would allow another short period of power and then cut out again.
My assumption was that the controller LVC is cutting in.
Plugged the charger back in but still not charging.
Have had the bike running on a stand for a few hours and can see the voltage slowly creeping down but still charger not working.
After running on the stand I took it out for another short trip - this time did not suffer cut outs under load - didn't go too far as in no shape to push the thing very far back home
Cycle Analyst now showing voltage at 52.4V but still no charger kicking in.
I've scoured the forum for LVC and charging issues. I'm thinking maybe the charger isn't starting because the pack is unbalanced and some cells are too high for charger to kick in?
I'm happy to take the pack apart and start checking individual voltages but was wondering if there were other things to troubleshoot first?
I've tested the output of the charger but I'm not sure what readings I should be seeing?
Any help or ideas would be much appreciated...

[Bikemad]

I've scoured the forum for LVC and charging issues. I'm thinking maybe the charger isn't starting because the pack is unbalanced and some cells are too high for charger to kick in?
I'm happy to take the pack apart and start checking individual voltages but was wondering if there were other things to troubleshoot first?
I've tested the output of the charger but I'm not sure what readings I should be seeing?

Hi Ben,

Sorry to hear about your accident, but it's good to know that you're making a good recovery.

Your charger should have an output of 58.8V when measured across the two output leads with a voltmeter.
If the charger's output voltage is correct, even if the BMS was preventing the battery from charging, you should still have seen 58.8V on your cycle analyst with the battery turned On and the charger connected, turned On showing the green LED, as the cycle analyst and the charger both share the same power connection on the BMS:





It might be worth checking the connection between the red battery + wire and charger + wire to make sure it is still good. 

If the charger was showing green with only 56.3V across the charger output leads, then it might be a problem with the charger unit.

If you gain easy access to the BMS, you can check all of the individual cell group voltages at the balance lead connector:



You could also check for any voltage variation between the battery Positive connection and the C- and B- connections while the BMS is accessible. 

You could even try connecting the charger directly to the battery output connector instead of the charger connector to see if it makes a difference

Alan
 

[Bedmountain]

Thanks for getting back to me so quickly Alan....
I'm reading 22.4 volts from the charger so I guess that's where the problem lies.
Is there anything I can do to troubleshoot that or am I in new charger territory?
Any idea what could happen to reduce the charger output while sitting in a shed for a few years?

[Bikemad]

Hi Ben,

Unless it's something simple like a poor contact inside an external fuse holder or a poorly soldered connector etc. I don't suppose it will be an easy fix.

If moisture has built up inside the charger, this can result in corrosion on the circuit board, or possibly electrical damage to voltage sensitive components caused by high voltage tracking along a damp surface.

It might be worth quickly taking it apart to see if anything obvious can be found like a dry soldered joint etc., but I suspect many of the electronic components used on the circuit board will be unmarked, which makes it very difficult to find the correct replacement components when something important has failed.

If you know someone who is into electronic repairs it might be worth asking them if they would have a quick look at it for you, but I suspect you may end up having to purchase another charger. 

Alan
 

[Bedmountain]

Thanks Alan

I had a look inside and there was nothing obviously damaged. I did have a talk with the supplier (Luna) and at first they suggested trying to adjust one of the pots but when I questioned if that should be done to increase the voltage by over 25V they agreed that it probably wasn't a good idea and didn't have any other advice (which is fair enough...)

A new charger it is then....