Hello all
Background: I'm running a pair of Yuasa NP7-6 (or is it ...6-7?) gel cells, 7Ah 6v, in series to give me 12v to a pair of mTronik Marine 15 ESC's, each of which runs a pair of Graupner 500E motors. I use a Robbe Lader 6 battery charger and charge the batteries as a pair at 500mA. Hope all that makes sense.
Questions and problems: here goes...
1. Around Christmas time, I snagged weed around a prop and put a very heavy drain on 1 motor which badly affected 1 cell in one of the batteries. Badly affected in that it would no longer take a charge. Took it back to the shop and clever man put affected battery on whizzy charger (gave it lots(?) of amps) and said it was now OK. Please explain (short words, please, not too many syllabubs).
2. I now appear to have a similar problem on 2 more of the same type of battery. I don't think they're taking a charge, or at least, 1 of them isn't as model appears very under-powered all of a sudden (yes, checked everything else). How does this happen and can it be cured.
3. The Lader 6 charger is handy because I can charge the Tx, Rx and drive batteries all from the 1 unit and all at the same time. However, I don't like the fact that there is no automatic cut-out once a set of batteries have charged, nicad or lead acid. Can anyone recommend an alternative that won't over-charge nicads or lead acids? Is it best to have separate chargers; nicad and LA? Should I charge the batteries separately instead of in series?
4. I've heard that a lead acid which is fully charged will hiss slightly and a gel cell which is just about to be killed by over-charging will do the same! Thoughts on this? How does one tell, for certain, that a gel cell is fully charged? They're not cheap items and I really don't want to trash any more than I really have to! (or burn the house down!)
5. What is the max current I can draw on those Yuasa batteries without destroying them? I'd like to increase prop size and possibly motor size (to a 600) but don't want to fry the cells.
Thanks for taking the time to read. Hope someone can help.
Mike