Q-84: I’m afraid that constant charging of my Ni-Cd and NiMH RC-system
batteries is going to prematurely wear them out and force an early replacement.
To help this situation, I usually bring my RC transmitters out to the field
three of four times before I resort to recharging them.
Do you think to be on the safe side I should resort to field fast charging those
batteries for a short time, to make sure I have enough power to fly at a
particular field session?
A-84: This is the proverbial accident waiting to happen! Regularly and
frequently charging your RC-system batteries using the supplied
dual-output-system chargers really doesn’t take away from the battery's normal
life cycle. These system chargers employ roughly a C/10, or what we call an
overnight rate.
A 500 mAh-rated Ni-Cd or NiMH battery pack requires 500 divided by 10, or 50 mA,
charge current. The overnight period is understood as being at least 10 hours.
But even 16 or 24 hours wouldn’t have any negative effects on your batteries.
You can recharge them two, three, or four times a week at the overnight rate,
and they still might last you five years or more.
However, if you fast-charge Ni-Cd and NiMH cells—especially those not intended
for fast charging—you will reduce their service life. In many cases, the battery
markings alone won’t really tell you if it can accept fast or elevated charge
currents.
Then on top of all this, your RC transmitters were not set up for anything but
overnight battery charging. The internal charging circuits (wiring and fuses)
are established for relatively low current levels. If you put a field fast
charger on your transmitter, you stand a good chance of burning out the internal
charger wiring, or at least the fuse.
Please take my word. Charge with your RC-system charger every time before you
go flying. Make sure you leave the charger on overnight. Do it as often as
you have the urge to fly. Going to the field several times with an uncharged
transmitter battery is a bad idea!