Why your bike needs a battery

Please read the charging system overview first.

While many cars can be driven a long way on a dead battery, you need a functioning battery on your bike to keep riding. Without one it will just up and quit on you. "Newer" motorcycles have solid-state electronic ignition systems, which are somewhat sensitive to variances in supply voltage. In fairly easy-to-understand terms, there are a lot of "troughs" in the AC waveform going into the regulator/rectifier, meaning that the DC coming out of the R/R will not be a nice flat line, but rather a stream of pulses. This must then be "smoothed out", and that is where the battery comes into play. It provides stabilization in the electrical system, as a capacitor would in a linear power supply design.

Layman's terms

Things that take DC like DC that looks like this:

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - _________________________________________________________(ground)

The 250's DC supply looks more like this, though:

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ _________________________________________________________(ground)

Which really annoys the things that take DC. But if you run it past a battery, it comes out like this:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ __________________________________________________________(ground)

Which is close enough to keep the DC stuff happy.