Battery resuscitation: Fettling
Bike wiring wizard Ferret on performing a spring time electrical health check
Getting your bike out for the first ride of spring is a good time to do a simple check on the condition of your bike’s battery and charging system. All you need is a simple multimeter with DC test setting and a basic understanding of electrics; if you can wire up a domestic plug and remember the basics of your O-level physics you should be okay.
Really you want 12.8 volts in a motorcycle battery (and don’t be a smartarse – we’re talking about bikes with electric starters, not six volt antiques with glow worm lighting). If your meter is showing less than 12.8 then put the battery on charge. And if, after an overnight charge it’s still reading less than 12.4-12.5 volts you should start thinking about a new battery. If the bike starts it’s tempting to hold out for as long as possible before forking out for a new battery, but you’re making the rest of the electrical system work harder.
Editor Wilson’s ageing Honda VFR has spent four months in the Bike lock-up, and he failed to hook it up to a trickle charger at the start of winter. Without starting the engine, the meter is showing 12.68 volts, so its worth attempting a restart without bothering with a battery charge. Pressing the starter button turns the engine over pretty smartly and it quickly fires up on two-three-then four cylinders. Happy days.
With the choke still on, and the engine at a fast idle the meter is now reading 14.49 volts, and there is no significant drop with the lights on main beam. That’s ideal, but anything between 13.5-15 volts is OK here. Less or more and you have issues. And if it’s over 16 turn it off quickly, you’re about to fry the battery, and maybe the ECU too.
Want to do a bit more? Work through the bike cleaning and checking electrical contacts, especially earths. And when it needs rewiring, then give me a call. Ferret (07765 832420)