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not charging at idle, 78 k8 normal?

Kannen91

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just a quick question, my 78 750 k8 does not charge at idle, the headlight does dull and eventually when the battery dies as does the bike. but rev it over 1200rpm and it charges to 13.1v and stays there throughout rpm range. does this mean my alternator is cooked? i have another one but i dont want to change it out if i dont have to. i have read some people say it is normal some people say it is not. also would having a brighter head light cause this issue? un sure how to test the stator, not sure if any components have failed or if they have, what ones..... HELP!
 
These motors charges first at +3K rpms. You should get 14,5 V at +4K rpms with a healthy charging system.
 
Yes normal not to charge at idle especially with the headlight on. Honda spec idle speed is 1000rpm +/- 100 rpm so make sure your idle isn't too low and bump it up to at least 1000 and it may help but they dont charge at idle with the headlight on. A higher wattage headlight will only drain the battery faster at idle.
 
Basically yes. But why? Only 13.1V in charging is indicating a charging issue. Turning off your headlight wont fix 1.4V extra. It should charge 14.5V with the headlight running. Unless you're running a whole ramp of extra lights up front.
 
You need to have the battery condition checked before condoning the charging system because it is charging just a little low. A sulfated or shorted battery can cause battery to die fast at idle and cause the charging system to be over worked.
 
its a 55w headlamp, its wayyyy brighter than a stock one. and the battery is pooched got to get a new one. going to try switching the head lamp and replacing the battery before i rip the charging system apart.
 
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