Setting Generator Charging Rate

Dave / Franklin MA

Dave / Franklin MA

Member
I had to replace my generator due to a squealing bearing. I installed a newly rebuilt from Bratton's so I trust that it's good. No adjustment has been made yet for charging rate, and I do understand how the third brush works. I am just a little confused about the rate to set it to and under what conditions.

Les Andrews says 10 amps, 8 for long trips. But the charging rate (as shown on the ammeter) varies somewhat depending on engine speed and load. At rest it seems to settle at about 10 amps; if I rev it a bit, it will jump to 12-14 and settle back down to 10. So far it sounds like it might be set close. However, when the car is moving, I've seen the charging rate bounce as high as 15-18 when I accelerated to about 45, and then it settles back down immediately when I let off the gas.

I really cannot compare it to the previous generator because that one had a voltage regulator installed in it. Some of my club members felt 10 amps was too high, and 3-5 amps was more realistic for daytime driving. Is that the normal behavior, and is it set correctly? Also, under what condition is the amp reading taken - at idle, under normal driving, or when revving it?
 
I set the rate to be zero when the high beams are on. If it gets a lot of daytime driving, I will switch the headlights on for part of the trip.
 
Your charge rate may be wandering due the brushes not being fully seated or bouncing a bit.. Time should cure that,or, you could help that along by applying a bit of pressure on the brushes with it running/turning.. I think 4-5 amps is fine for daylight operation and about 12-14 for night time.. I don't like to run these at any more than that.. I recommend installing one of Tom W's EVRs and not worrying about the adjustments..
 
I set my max rate about 14-15, just enough to have a +1 amp with the halogen headlights on, the Optima likes the higher charge rate coming out of sitting for a while, if I am driving a hundred miles in daylight I will turn on the headlights for 30-40 miles of the drive, it has worked for me, the Optima is still going strong at 14 years and it never gets charged when I am not driving.

Read in the service bulletins about setting charge rate, think about your use, ---the ratio of sitting, driving, and night use, in the 36 service bulletin is another article about setting charge rate that is good.

At a normal idle speed you should have a discharge, by about35 you should have about the max charge rate for your brush setting.
Testing with a bad or discharged battery can cause strange results.

If you don't have the "feel" for seat of the pants adjustments a voltage regulator could be better for you.
 
I hope you saved the EVR. It's the best way to run the charging system.

With no EVR, I'd run the generator at about 3 amps for daytime driving. Then move the brush up to about 10 amps for driving with the headlights on.
 
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