My wife drives a Honda Helix 250. She has and electric jacket liner, that I believe draws 77 watts. Not knowing but I'm guessing that the alternator may be too small to keep the battery up to full charge if she rides with the jacket turned on, even 1/2 way for 2-4 hours. I have a spare 12 AH motorcycle battery and was thinking what if I were to charge it full up and hook it up parallel to the bike battery? This would probably be enough power for the bike and the jacket for the 2-4 hours. But the question is, is this too much of a load for the alternator possibly burning it out???? Any thoughts or suggestions will be appreciated.