This maybe obvious to some of you, but I have included here as it gives real data to back up the practice.
Before examining my Berlingo batts, I ran the vehicle until low charge light came on (at about 45%) to help identify the weakest cells. All cells (within the middle pack) were within 0.02v apart from one which we replaced. Anyway, we ran around the other cells with a battery tester set to 125A and tested for about 5 seconds not expecting any issues. However, one of the cells dropped by just under a volt over the 5 sec period, even though it was in a low state of charge and its voltage was within 0.02 of the others at the start of the test.
So the moral of the story is that it is worth doing a load test of 125A for 5 secs even if the voltage looks ok.
Summary :-
Dudd cell
...o/c voltage = within 0.02 v of other good cells.
...125A 5 sec load volt drop = approx 1 v
...recovery time to 0.02v of other good cells = TBC
Good cells
...o/c voltage = 6.02v (50% charge)
...125A 5 sec load volt drop = approx 0.25 v TBC
...recovery time to 0.02v of other good cells = TBC
Test SAFT batterys under load as a well as by voltage
Re: Test SAFT batterys under load as a well as by voltage
Might also be worth carrying out a capacity test as it may well be that the battery has just become "un-blanaced" from the rest of the pack.
As you say terminal voltage cant be used an indication of condition, load testing or better, capacity testing is always a safer bet.
ChrisB
As you say terminal voltage cant be used an indication of condition, load testing or better, capacity testing is always a safer bet.
ChrisB
I reject reality and substitute my own !!!!!!
Re: Test SAFT batterys under load as a well as by voltage
That is the plan
The unbalancing is unlikely as I did part initialisation charge (which only got me an extra 10%)
I will take more accurate readings when rerunning tests.
The unbalancing is unlikely as I did part initialisation charge (which only got me an extra 10%)
I will take more accurate readings when rerunning tests.
Re: Test SAFT batterys under load as a well as by voltage
Really depends how far out of balance a battery or even a cell has become from the rest of the pack.
The fact it just sagged underload makes me think there may not be a lot wrong with it, that say an extended charge wouldnt fix Dunno these Nicads are funny old beasts but todate I've really only ever had them fail or work with nothing much in between.
ChrisB
The fact it just sagged underload makes me think there may not be a lot wrong with it, that say an extended charge wouldnt fix Dunno these Nicads are funny old beasts but todate I've really only ever had them fail or work with nothing much in between.
ChrisB
I reject reality and substitute my own !!!!!!
Re: Test SAFT batterys under load as a well as by voltage
Were the modules fully charged before load testing?
Collapse of voltage when almost discharged is normal. Try reconditioning by cycling at 5 amps down to a threshold of 2 volt. Pulse charging at very high efffect of 150A kan also help to skift to capacity under 5 volt up to a more useable voltage.
Collapse of voltage when almost discharged is normal. Try reconditioning by cycling at 5 amps down to a threshold of 2 volt. Pulse charging at very high efffect of 150A kan also help to skift to capacity under 5 volt up to a more useable voltage.
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