My bike has a Baja Designs kit on it, including the original tiny NiCad(?) battery. It has been in there since '99. It has lost most of it's charge over the winter, and it's too cold to ride enough to try to charge it, but I may soon need to prove it will light the taillight w/o the bike running for the required 20 or 30 min. Can I use my little motorcycle trickle charger on this? If not, what might work? If a new battery is necessary, are there any better ones available (not that I can complain about the longevity of this one, but technology may have improved over the past few years.) Size is an issue. This one is @ the size of a pack of smokes.