No charge at idle speed

[a70eliminator]

I was out tooling around last night for maybe an hour or so after dark, got back to the docks and shut it off, get ready to load and it almost didn't start back up battery real weak, I noticed that my 12v guage drops to below 12v at idle and comes up to above 12V at anything above idle, my idle is about 550-600 and seems too low for the charging system to keep up with the runnng lights, is this typical and I just need to charge my battery manually once in a while? This was about the first time for tooling around at night at idle with lights and accys going.

 

[Daviet]

Re: No charge at idle speed

I had that happen to me once when I replaced the alternator, come to find out the pulley size on the new alternator was a little larger than the old one making it turn a little slower at the same RPM. I used the pulley off of the old alternator and it worked fine.
There should be no need to externally charge your battery if your charging system is working properly.