A note about some (or all?) Battery Tender brand chargers -
The one I have will not light up & begin a charge cycle on a completely dead battery. A call to the factory revealed that they need to sense at least some voltage in the battery before they will light up. I don't recall now what the low threshold is. 4 volts maybe? One can induce these chargers to fire up by applying some voltage from another source, like another battery charger applied for a second or two, or the like. I bet a 9 volt battery would jump start 'em too. Not sure.
More battery trivia - while out charging my wife's car battery with my trusty / rusty, a guy gave it to me for helping him move furniture NAPA car battery charger, (his name was Rusty too - huh, that's weird) I happened to have my digital volt meter at hand. The charger in question puts out 15.5 volts -- ouch -- probably a might too much for a little bike battery.
