Bringing batteries back to life
#1
Bringing batteries back to life
Hi all,
I have a box full of old GP 3700s... when I put them into my charger, they show around 0.6V.
I have tried several things, but I can't seem to bring them back to life...
I have tried cycling at 0.5A charge/0.5A discharge... this works, but as soon as I try to charge at around 3.7A/3.7A discharge, the cell charges at ~1000mAh and discharges only 100mAh.
One of the cells I tried 3.7/3.7 on yesterday vented on me.
Should I just go through more 0.5/0.5A cycles, and slowly up the current as I go along?
Or do you have any other better methods of bringing batteries back to life? I also thought about doing a little bit of flex charging on them, but that is only recommended for NiCd as far as I gather?
Thanks in advance.
I have a box full of old GP 3700s... when I put them into my charger, they show around 0.6V.
I have tried several things, but I can't seem to bring them back to life...
I have tried cycling at 0.5A charge/0.5A discharge... this works, but as soon as I try to charge at around 3.7A/3.7A discharge, the cell charges at ~1000mAh and discharges only 100mAh.
One of the cells I tried 3.7/3.7 on yesterday vented on me.
Should I just go through more 0.5/0.5A cycles, and slowly up the current as I go along?
Or do you have any other better methods of bringing batteries back to life? I also thought about doing a little bit of flex charging on them, but that is only recommended for NiCd as far as I gather?
Thanks in advance.
#2
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ok, this is my method i use for old laptop cells and such like. i managed to get some 15 year old 1800 ni-mh's back to about 1300mah this way.
1. leave them at 300mah for a few days on a power supply at 1.5v/cell.
2. use a pulse width modulation charger, or the one you can safely charge alkalines with to cycle the individual cells a couple of times.
3. drop the cells from 6 feet onto a concrete floor (positive cap up! thats the weak spot) to knock the crystals off the inside, and charge on the PWM cahrger again. repeat this process a few times. i was shooting mine with a BB gun instead of dropping them too.
4. after a few cycles of this method i simply charged them up using a normal ni-mh household charger, made into a pack and used it. (only for a portable amplifier though. the cells were in such bad shape they only gave about 1C)
ok, it seems destructive but it seems to work...
1. leave them at 300mah for a few days on a power supply at 1.5v/cell.
2. use a pulse width modulation charger, or the one you can safely charge alkalines with to cycle the individual cells a couple of times.
3. drop the cells from 6 feet onto a concrete floor (positive cap up! thats the weak spot) to knock the crystals off the inside, and charge on the PWM cahrger again. repeat this process a few times. i was shooting mine with a BB gun instead of dropping them too.
4. after a few cycles of this method i simply charged them up using a normal ni-mh household charger, made into a pack and used it. (only for a portable amplifier though. the cells were in such bad shape they only gave about 1C)
ok, it seems destructive but it seems to work...
#3
Thank you,
any other opinions?
any other opinions?
#4
Tech Adept
bringing batteries back to life....
CAN BE DONE!!!!!
Try a "ZAPPER" once or twice!
CAN BE DONE!!!!!
Try a "ZAPPER" once or twice!
Last edited by il-gufo; 03-21-2008 at 10:13 AM.
#5
tray them untill all the cells are at "0" volts. Then deadshort them by soldering a wire from the neg. to pos. ends of a complete pack. Let them sit for a while and then charge the pack at 5.0 amps. cycle them a few times but be sure to tray them down to zero volts before shorting them.
#6
No no. If the cells are still good, put a little charge in them (1000mah) and let them sit for a few days. Then discharge them and charge them back up.
#7
So,
I tried charging them using flex charge on my Cell Master...
I started off low (0.5A) with a lot of flex (7), and kept upping the amps after 3 cycles... when I reached around 3.7A, I started lowering the flex all the way to 0 after a few more cycles...
The batts now discharge at around 5A np, not great, but OK I guess...
I tried charging them using flex charge on my Cell Master...
I started off low (0.5A) with a lot of flex (7), and kept upping the amps after 3 cycles... when I reached around 3.7A, I started lowering the flex all the way to 0 after a few more cycles...
The batts now discharge at around 5A np, not great, but OK I guess...