Demetri
Sure you can use an aa charger to charge N cells!.. N cells or just under the size of c cells, and I do it all the time..Most of the cheapo AA chargers are in the order of 50 ma charge current, and will charge any 1.2 volt nicad, being it a AA, N, C, D etc.
Of course the larger the cell, the longer it may take.
I keep hearing references to these "Forgiving" solar chargers..Well, Im afraid that if I put my 300 watt PV system on a nicad (its a solar charger ;-> ), it would pop it in seconds..
and to the reference of using resistors to limit current, this is not really a good idea, since once the voltage will continue to increase once the nicad ( or NiMh ) has reached it nominal charge voltage.
the easiest and simplist way to control the charge of a nicad is "voltage based" control, meaning that you would limit the voltage to the nicad at say 1.45 volts, and then the current would taper down to near nothing, and keep the nicad from overcharging.
"Current based" chargers I would shy away from, since they tend to keep the current constant, and allow the voltage to rise.
now, you really cant go wrong with with any charger that limits the current to about 50 ma., and can charge pretty much all day long.. I have built a few "smart" chargers that
fast charge at a hi ma rate, then taper down as it senses the voltage approaching nominal.
Some of the battery packs in my handheld ham eq. use a thermistor, that feedbacks temp data to the charger, and regulates the current based on the temp of the battery packs..
This is used in some of these "2 hour" quick chargers.
Anyway, have fun!
JimU