Combines 1680 alternator

Try a new volt meter. I have replaced lots of them and it shows alarger charge.

I've been having similar problems on my 1988 model 1660. It has the Bosch alternator and seems to run fairly consistently on the black line, dead centre of the gauge until I turn the lights on and have the cab fan running. Then it is right down to the low side of the green almost on the white cross hatched area. Fortunately I have the same alternator on my 7130 Magnum and did a switch onto the combine. The tractor alternator does seem to run a little higher voltage than the original combine alternator but still rarely runs above the black line. I've had a new regulator installed a couple of years ago but it did not help much . I've been curious if this is normal or these alternators have a low charging rate.

We have the same deal with a 1688...volt meter reads low but we haven't had a problem with low voltage...go figure. I am happy to have gotten four seasons out of the alternator, unheard of in our operation before. just don't forget to blow the dust out whenever possible

Jcloar, I've had the same experience. Turn key switch on. Notice the reading, start machine, when the engine starts and is reved up the needle should show an increase in voltage from where the needle was prior to cranking with the key on. 13.5 to 14V should be OK.

13.7 to 14.2 is where rhe bosch alt. puts out. don't watch it on combines because it has a idiot light on it. reason of change from delco. was the bosch in hot weather has ahigher output of amps. a battery is fully charged at 12.7 , so why have one boiling batterys at 15 volts.