Hello
I've noticed in the past few days that my ammeter is reading a little lower than it should. Usually it reads around 14.5 volts. Lately it's been hovering around 12-13.5 volts. The batteries are charging as I have been able to start my truck all last week, but I'm wondering if, for some reason, my batteries are low. I did leave my parking lights on for about 40 minutes, twice, before this happened but I didn't notice anything. I put the batteries on a trickle charge for 5 hours and it seemed to help.

It's a 1988 F250 diesel, dual battery (1100 amps each), installed new alternator and voltage regulator earlier this year, new positive battery cables.

Any ideas?

 

how old are the batteries? maybe do a load test on them????

 

Check belt tension.

Check the alt wiring connections.

As long as you are around 13.5v, it should keep the batteries charged. The voltage will naturally go down as you put more load on the system(headlights, wipers, defrost, etc.)

 

The batteries are 18 months old. I took it in to the local battery shop and he tested them they came back at 12 volts by them selves and 12.5 volts with the engine running. When I have no load on the system, it should read just under 15 volts, so I'm 2 volts shy for some reason.

 

it's got to be the alt again, Gigger

 

Was this a "new" alternator you installed last year or a rebuilt one? Sometimes it takes several rebuilt ones to get a good one.

 

Franklin X2 , I hope you have your bill