My uncle stores his Ultra in a rental garage which the owner won't let him plug his Battery Tender into the electric. Was trying to figure a way around this and thought of this . Perhaps getting a pretty good deep cell battery and pigtail this to the bike battery. Then, every couple of weeks, taking the deep cell home and charging it. Does anyone know if this might work? Best I could think of... wonder if anyone has any other iteas. Thanks.

 

yes , i did that at a condo.
i used a marine/car battery? and then a voltage converter and then plugged the battery tender into the converter...i had the battery tender and voltage converter from before so i just bought a large cheap battery..the only problem was the converter i used was about 400 watts and had a fan so it would last less than a week...if i had to do it again..i would find the lowest voltage converter that would run the battery tender and then give that a try...an easier way if you have sun light or garage lights in parking area would be a solar car battery maintainer...

 

You need an inverter as a battery charger actually applies more than 12 volts in order to charge so just jumping the two batteries won't really do you any good.