Charging, discharging and storing SANYO sub-c batteries.

[Bormac]

SANYO sub-c batteries.

Its been such a long time since I have run these old school cells that I have almost forgotten how to get the most from them. Even though I am no longer racing I still find the old cells of interest.

I am always looking for good condition SANYO's from back in the day and would like to charge, discharge and care for the packs that I currently have. While I am well aware of the lipo technology and like the seemingly unending run times (in comparison), I still want to use these old cells for my own entertainment.

I currently own a few Novak Digi-Peak Plus chargers and a selection of cells ranging from 1200 through to 2000 cells both matched and loose non matched.

Who can recommend some good charging techniques for the old SC, SCE, SCR and SCRC type cells?

[THEYTOOKMYTHUMB]

I think just a straight charge at about 3.5 amps would keep them in good running condition. Discharged as hot and fast to zero as possible. 4.5-6.0 amps for hotter runs, but shorter overall life. I still have some SCR cells that I run very rarely(because mine are in bad condition anyway). The 1985 IFMAR vids prove that those cells can still provide some big balls if used properly.

[V12]

For SC cells it´s difficult to say as at that time there were no advanced chargers. I remember that time some guys were even just using a resistance cable for charging or time controlled chargers what were far away from electronic devices. But I think also something in the 3-3.5 amps range should be OK.
For SCR cells you could maybe a little more as 4 amps and the SCRC cells I used 5-6 amps.

I don´t know this Novak charger very well but if you can choose the sort of charging current I think I would use linear charge for SC and SCE and pulse charging for SCR and SCRC also 2000 cells. SCE cells are touchy and I think I would not use them again.
From all of the older Sanyo cells I liked the SCRC SP cells the most. These were special versions of the SCRC cells and somewhat more heavy what was the only way from telling if it´s a SP or ordinary SCRC cell if these were packed in black heatshrink. If red heatshrink than it´s an ordinary SCRC anyway.
Anyway the SCRC did like being treated hard. So hardpulse charging was the best way and charging up to at least 45°C (don´t know how much is this in Fahrenheit) and also just in time what means not more than 5 minutes before the race. And maybe the most important thing discharging to zero before charging. But we never did like the deadshorting thing and preferred using a resistor over each of the cells.

[minichamps11]

Anyone know what causes old SC and SCR batteries to leak horrible white crystalline stuff? I have some cells stored in a plastic box and they are slowly wrecking themselves, leaking their internals. They have been stored discharged and not shorted out. I wanted to put them in some shelf queens but no way I'd risk that at the moment.....

[V12]

It´s happening often with old cells. That stuff is the electrolyt what was leaking out and then has dried. I think it doesn´t hurt the car but it may be not that healthy.

[ROH73]

I edited the Q&A below from a 2002 RCCA article with Jim Dieter. It pretty much sums up how I treated my batteries when I was racing in the late 80s.

Q: At what amperage should I charge my packs? Do packs of different capacities require different charge amperages?

A: As a rule, Ni-Cd batteries can be charged safely at twice their rated capacity; for example, a 2400mAh pack can be charged at 4800 milliamps, or 4.8 amps. Four amps is a safe rate for good all-around performance with any Ni-Cd battery. Higher amp rates can be used to deliver slightly more punch, but this is only effective if you run the pack immediately after you've charged it. Avoid amp rates in excess of three times the pack's capacity, as they may lead to overheating of the pack. Unless you're in a hurry, stick with 4 amps.

The trick to getting maximum performance from any pack is to run it immediately after charging while its voltage is highest After the pack has been removed from the charger, its voltage begins to flatten out.


Q: My charger has adjustable voltage threshold. What should I set it for?

A: For Ni-Cds, it depends on your pack. Unmatched packs and older batteries that have a tendency to false peak may need a higher voltage threshold setting, while new matched packs can be charged with a lower setting. If your packs are coming off the charger closer to "hot" than to "warm," try reducing the voltage threshold setting.


Q: My charger has "pulse" and "linear" settings. Which should I use?

A: Either setting is fine for Ni-Cd packs, but linear charging is generally preferable. Pulse charging can be helpful in getting a full charge into packs that like to false peak, but there's no performance advantage.


Q: At what amperage should I discharge my packs?

A: Regardless of cell type, it's best to discharge the pack at an amp rate that approximates what the pack encounters under race conditions; generally, 20 amps for stock and 30 amps for modified racing. If you're using a bulb-type discharger with no. 1157 bulbs, use a 10-bulb discharger for a 20A load or a 15-bulb unit for a 30A load.


Q: How deeply should I discharge my packs?

A: At the very least, you should run your Ni-Cd packs until the car slows to a crawl. If you have a bulb-type discharger, dump the cells until the bulbs go out. For maximum discharging (and maximum cell capacity when you recharge), use a discharge tray to individually discharge each cell down to 0.5 volt per cell, or 3 volts for the entire pack. For most racing, this is as deeply as any pack needs to be discharged. If you don't fully discharge your pack by at least running it in your car until it dumps, the pack will "remember" that it was recharged without being fully discharged. This will result in a very "flat" performance when it is discharged past the point where you have trained it to expect a recharge.

Q: Will it hurt my packs if I run them more than once a day?

A: Recharging and discharging a Ni-Cd pack the same day won't hurt it. The voltage is usually better on the second run, but there is a slight loss in run time. This is good news for stock racers; the increased voltage gives more punch, and the minor loss in run time isn't an issue (unless you've geared the car to dump 10 seconds after the tone). If you continue to dump and recharge the pack, subsequent runs will be a little "flat," but you won't be damaging the cells. If you discharge and store the pack as this article explains, it will once again deliver maximum performance.

[Bormac]

Great info in this thread. Thanks guys.