The recent change in weather almost left me stranded the other day when I tried to start the bike and had a partially discharged battery. Since dad and I run a maintenance and salvage shop, we have a surplus of old 12v ELT batteries. So I made an emergency "juice box" that will hopefully never have to get tested. Wiring it up was very simple since it uses a 9v type plug, and I have a hot wire coming off the positive terminal to a bolt on the plastic under tray. I won't be able to start the bike off of it, but hooking up the juice box for a few minutes should bump the bike's battery enough to get the bike started.
The battery is fine, but the other day it acted a little weak since it got cold, happens every year. It was moreover just something to tinker with. Since the bike is so dependent upon the battery, I figured this little device might come in handy.