NiMH Cells Memory effects
03-04-2007, 10:46 AM
#1
NiMH Cells Memory effects
Hi All,
Sorry if this has been discuss before. I have some queries in mind which i encountered.
Got some cells from a friend, 6 x NOSRAM 3700Mah Cells side-by-side, he has been charging them at 2.0A, peak 10mv/C.
I realise that when i charge at 4.5A 4mv/C, it peaks very fast. I have not try 2.0A peak 10mv/C yet.
Is there a possibility that the cells are used to charging 2A peak 10mv/C which caused the problem that i am facing? I tried a couple of times, even trying 15mv/C and it peaks at only about 300Mah charges.
Currently trying to charge at the same setting my friend did but just hope to seek expert advise on this issues. Thanks.
Sorry if this has been discuss before. I have some queries in mind which i encountered.
Got some cells from a friend, 6 x NOSRAM 3700Mah Cells side-by-side, he has been charging them at 2.0A, peak 10mv/C.
I realise that when i charge at 4.5A 4mv/C, it peaks very fast. I have not try 2.0A peak 10mv/C yet.
Is there a possibility that the cells are used to charging 2A peak 10mv/C which caused the problem that i am facing? I tried a couple of times, even trying 15mv/C and it peaks at only about 300Mah charges.
Currently trying to charge at the same setting my friend did but just hope to seek expert advise on this issues. Thanks.
03-04-2007, 11:02 AM
#2
False peaking can be down to a couple of things...
1) Old cells with higher resistance
2) Cold ambient temperature/cold cell temperature (i.e. substantially less than room temperature)
3) Pack out of balance/faulty cell in pack.
It sounds to me like these are old cells and your friend has been managing to charge them because the low charge rate doesn't have to fight the resistance in the cell.
Anyway, it would be good practice to try equalising them on a tray and make sure the room is a bit warmer if you are trying to charge them in a garage or shed.
1) Old cells with higher resistance
2) Cold ambient temperature/cold cell temperature (i.e. substantially less than room temperature)
3) Pack out of balance/faulty cell in pack.
It sounds to me like these are old cells and your friend has been managing to charge them because the low charge rate doesn't have to fight the resistance in the cell.
Anyway, it would be good practice to try equalising them on a tray and make sure the room is a bit warmer if you are trying to charge them in a garage or shed.
03-04-2007, 03:09 PM
#3
2.0a and 10mv per cell 
6.0amps 4mv/cell is about average those packs are probably junk.
6.0amps 4mv/cell is about average those packs are probably junk.
03-05-2007, 06:16 AM
#4
Originally Posted by schmelme
2.0a and 10mv per cell 6.0amps 4mv/cell is about average those packs are probably junk.
6.0amps 4mv/cell is about average those packs are probably junk.
03-05-2007, 06:25 AM
#5
Drain them them past zero and let them sit on the tray for about 5 or 10 minutes past zero, dead short them and let them sit for a day or so. Then take the dead short wire off let sit for 30 minutes. Then charge at 3 amps 4mv peak. Try this and see what it does? Are they GP 3700's?
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