Topic: Rectifier CB400/4

[KevinUK]

My bike's been damaging batteries and I thought it might be a short, but a friend told me his CB400/4 did same and rectifier to blame. So I fitted new rectifier and battery yesterday, got bike going, but worried new rectifier gets very warm. Is this normal due to current passing through it, or should I be looking at a specific problem?

[oldbiker]

ANY rectifier will get warm, but just how warm is warm? If it's too hot to touch, then that is too warm. You must start by checking the voltage at the battery when charging and the current being fed into the battery. Normally the voltage should be between 12.5 and 14.5 depending on load and revs. The current will depend on the state of charge of the battery and what is switched on and will normally lie between about 1 and 5 amps. Any more than this and I would be looking for the fault!