retterath wrote: Why? The battery acts as a sort of shock absorber for the electrical system. Even if you kick start the thing, the lights still need the battery.
You're right about the battery acting as a 'shock absorber' - but you don't need a battery if you have a battery eliminator, which is what OP is asking about. A Battery eliminator is an equivalent to a battery - it has high capacitance and low resistance. I.E. it's a capacitor.
The biggest difference between a battery and a capacitor is that a battery is designed to hold charge and keep the voltage consistent when discharging. Capacitors will not hold as much charge, and their voltage will drop quickly, but they can provide a large amount of current in that time.
Capacitors are also good at smoothing out voltage, which is what you want. This is also why you never disconnect a battery from a running vehicle - you can get big voltage spikes, which can be particularly bad for modern electronics. The big problem here is that you will need a really big capacitor to match the equivalent capacitance of the battery.
It can be done, but only if your current electrical system is up to it. The battery does very little apart from acting as a capacitor once the bike is running - unless you electronics are old and a bit worn (quite likely!) and you turn on your headlight at idle.
Do a search for battery eliminators - you can get them, they're just a big capacitor. But they'll perform no better than a tiny battery in the best case scenario.
