Troubleshooting common 12V battery problems

Diagnosing and tracing faults with a motorcycle's electrical charging system can be a daunting prospect, but with a basic understanding of the bike's charging system you can usually get to the nub of what's wrong. We asked the battery-saving experts at OptiMate to outline the main components of the charging system, and the symptoms of the most common problems encountered with them

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Key components of a charging system

The first thing to get your head round is what exactly you're dealing with. Most motorcycle charging systems consist of just three main components: a battery, an alternator, and a regulator/rectifier.

In basic terms, the battery stores the electrical energy that components, like your starter motor and lights, need to work when the engine is not running. The alternator generates the current needed to power those components when the engine is running, as well as keeping the battery charged.

The regulator/rectifier rectifies (changes) the alternating current (AC) produced by the alternator into a direct current (DC) that can be received by the battery. It also regulates the amount of current to prevent overcharging.

Amber warnings

The red flag that there's a fault somewhere in your bike's charging system is, of course, that your bike won't start. You'll just hear a 'click' from your starter motor, or nothing at all. There are some early 'amber' warnings that something is up though, these include:

SLOW CRANKING

If the engine struggles to turn over when you try to start it in the morning, it could be a sign your battery is on the way out.

BATTERY WARNING LIGHT

Most bikes have one. If it comes on whilst riding it means that your battery is no longer being charged by the alternator.

HEADLIGHT

If your bike's headlight gets brighter as you rev the engine and dims as it falls back to idle, this could be a sign your regulator isn't working properly.

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