All of us depend heavily on a few little 1.25 volt wonders to keep our planes flying safely. Yet nicad batteries remain one of the most neglected and misunderstood elements of our models.
Most transmitter and receiver packs consist of ``standard'' slow
charge cells. Such cells are designed for an overnight (10-14 hours) charge
cycle with a current of 1/10th their capacity. That is, a 500 mAh
receiver pack may be best charged for 10(ish) hours at a 50 mA current
rate (since 50 mAHr 10 Hr = 500 mAH).
A more rapid 1 hour charge may be occasionally done with a current equal to
the capacity rating (for our example of the 500 mAh receiver pack, this is
500 mA, or 0.5 Amp).
Electric power nicads must withstand torturous charge conditions by comparison, as we expect to charge a nicad pack in 15 minutes! Since normal nicads aren't built to withstand this sort of abuse, electric fliers use rapid-charge cells, which are designed for high current charges and discharge loads. For such cells, one can readily charge the cells at a rate of 4 times the capacity in 15 minutes. For most electric nicads, which fall in the 1000 - 2000 mAh capacity range, a 4-6 amp charge rate is appropriate.