Rejuvinating old cells

[losidan]

wonder if I can ask a question about cells?

i have found three sets of team orion 2400 cells I forgot I had. They are currently in saddle formation.

I was thinking of getting two packs rebuilt into 4 cell packs for me 12th scale. I know they must of been sat for at least a year. Is there anything I can do to rejuvinate them if they are a little flat, so to speak. My charger has option to charge at 1,2 or 4 amps.

I wondered if a charge first at say 1 or two amps would be beneficial to breath some life into them?

frankly i know cock all when it comes to cells so any ideas would be most welcome.

ta
dan

[neiloliver]

These are Sanyo NiCd 2400? If so, this is good news as they have sintered electrodes and are rather bullet proof. The cells will have totally discharged and the electrolyte settled out of the seperator during storage, so their internal resistance will be initially higher and you may get some premature negative delta V charge termination for the first few cycles (this is where the voltage of the cell rises during the first few minutes of charge and then drops, fooling your charger into thinking the cells are fully charged when they are not). Best thing to do is put them on a 1A charge and keep an eye on them. They should charge for around 2.5 hours but if they terminate charge early put them back on charge again, it is ok to keep doing this unless they get warm (>45C). Once charged, discharge them to 1.0V/cell and repeat the process (charge and discharge). When full discharged, leave them for a few days, then come back and measure their voltage. Good cells will spring back up and still be >1.15V. If any have internal shorts then they will drop off rapidly.

Hope this helps.

[losidan]

top stuff, thanks mate

[stefke]

Another good way to keep NiCd's in top condition (or rejuvinating them) is cycle them on a flex charger (Tekin 112, Schumacher CCD, ...). It takes all the "memory" out.

The second generation Sanyo 2400's are perhaps the most bulletproof and reliable cells out there. Loved them !