Home made Batteries very hot during charging!
Hi to all.
I have made battery packs for my old RC toys, their batteries were dead. One was a 3x 1,2v 2/3AAA so 3.6v and the other a 5x1.2v 2/3AAA so a 6v battery. I made several battery pack (rather well now I finally mastered the soldering technique, using hot soldering (I saw it was better to make yourself a special soldering kit with a 12v battery and a condenser, but I went for the lazy option)). They work well BUT:
-when I charge the 6v ones on their original charger (it is a timer charger with a 30min timer, you plug in the car 12v plug). It charges but the batteries HEAT A LOT! And one 30 min charge isn't enough to charge them fully.
I am supposing that the original batteries had a lower amperage (maybe 200 mAh per cells) and I suppose the ones I bought are greater in intensity (Amperage), so I suppose it takes longer to charge. Can that be correct?
Also, I am having to charge them twice... Isn't that not very good for the battery? (should I rather set the timer to 30min and come back before the 30min are finished to add another 15-30 minutes to it? (Even if the battery is very hot??) Or can I let it stop, and then later dd another 30 min charging?
(any ways of calculating the time of charge required knowing the voltage and amperage??)
Thanks a lot for all you help...
Best!!
PS: the batterie are NiMh 400 mAh each.