prblem with berlingo ev

[timpootle]

I have followed the instructions here for my 'normal' Berlingo, which has much the same fault as the OP had. Low volt light on at 40% with 31 miles covered.

Voltages measured before charging, but after lunch on my return, so half an hour resting.

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All measured voltages (even the tricky front one)
Total voltage -    165.3v
Top front pack -    25.0v
Rear pack   -       38.9v
Centre pack   -     68.7v
Bottom front pack - 34.1v

Total by addition - 166.7v (my meter isn't very accurate )

Can someone post here with the voltages we SHOULD expect, for future reference as much as my own current problem.

[Grumpy-b]

Looks like the bottom front has a duff cell.
If you divide the pack voltage by 6 for the front lower and rear, 11 for the centre and 4 for the top pack it gives you the average voltage per cell.
The nominal voltage should be 6 but in reality we see anything from about 6.3 to 6.7 when charged.
Your bottom one is averageing 5.68v. I would guess you have one or two duff cells. No choice but to drop the pack and check them out individually.

Grumpy-b

[timpootle]

Those were the figures I was hunting for! Thanks, GrumpyB

Yep, pack out time. Handily I have a mountain of lithium lying around here...

[timpootle]

Another silly question, if anyone can help.

I have charged up the car again now. If I remove the battery box in this state, will I be able to identify the duff cells? Or should I run it flat again?

[Grumpy-b]

its better to do it when they are partially discharged. Or you can momentarily short out each cell in turn noting the voltage before and after. The failing cells will give a much lower voltage post brief shorting (count to two while shorted).
Even using the vehicle and beiing prtially discharged, some cell voltage will recover in the time it takes to extract them. But its is easier to track the bad ones down.

Grumpy-b

[EVan]

Please don't "short out" these modules! They can and do blow up.

It's better to apply a load of a low resistance to draw 100A or so, but make the connection remotely (away from the battery) so that you don't damage the battery post or ignite any hydrogen in the cell with the sparks.
Measure the voltage while the load is connected. If it immediately falls below 5V, that one is bad.

[Grumpy-b]

Good point Evan. I have used a 12v starter as a load and that worked fine. Certainly enough to depress the voltage momentarily.

Grumpy-b

[ChrisB]

yeah I wouldnt actually post short these modules

They can go bang in quite a spectacular way and certianly wont do your hearing much good at the very least.

ChrisB

[timpootle]

Well, the front pack is out. The car was down to about 70% when I removed it, and I have 6.5v on 4 cells, 5.1v on the other 2.

What do I do now? Join the queue at SAFT's door? Scrap a perfectly good car for spares? Recondition the cells? Is this even possible?

I know there are several people out there in the same position as me. What can we do?

I turned on my computer this afternoon to read the STM5 manual I have around here somewhere. Maybe that be enlightening.

Help!