Re: bike wont hold a charge
my advice to the both of you would be to buy new batteries because you'll kill them by draining it and recharging all the time, if it dies after putting the new one in then go from there, try the rectifier like you said. as far as the pinging try a higher octane, that never hurts. I can't imagine the fuel system cleaner or carbon cleaner, whichever you're talking about hurting the bike, all that stuff is just meant to burn anyway and since a car and a bike both have internal combustion engines there can't be too much difference in how it burns what is put in it.
if you can't convince them, confuse them.