Hitchcocks Forum

Electric expert wanted!
A friend of mine has an old 350 Honda. He's getting 13.7v at the battery with engine running at fast tickover.
Is this OK? I know the ideal is about 14.2v.

I have no idea if that is correct for that bike but on some of the old Honda's they had six coils in the alternator and used two of them when running without the headlights on and switched to all six with the lights on, it was easy to alter the wiring to run with all six coils all the time improving the amount of charge ideal in the winter with shorter runs and heavy traffic as when I used a bike for a daily run to and from work, not sure if this appliers to your friends bike but it just came to mind

I would think that even with a lesser number of coils operating the voltage would be the same, and bringing in the other coils with the light switch, like the old Lucas system, would increase the Amps to cope with the extra load. I would say 13.7 is a decent charge voltage, I usually expect about 14 volts, any slight drop could be down to old wiring and connections, causing a little resistance in the wiring. Try it with the lights on and see if it picks up a little.

To some extent the battery will regulate the measured voltage i.e. you won't see the charging voltage but the battery voltage. Some cars have a diagnostic mode and will display the battery volts - 13.7V is good.

Simple instruction video. (Well it is for Americans.)

Thanks guys. We will temporarily fit one of those cheap digital voltmeters and keep an eye on the voltage under riding conditions. Also found a couple of dodgy looking connectors which will be replaced.

Yes jefrs, I understand the battery will "damp" the charging voltage. The temporary voltmeter will hopefully tell us more.