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i have a 92 f-250 7.3 i.d.i.....she has 2 new batts.,new alt,and yet the bats will not charge 100%,doe this unit have a votage reg?....what would cause this.....please help...i have been now stranded waiting for a jump twice now
What condition are the cables in and are they tight? Even a little corrosion will reduce the ability to take a full charge. The voltage regulator is built in the altenator. Even if the alt. is new, it may not be good. The joint that sold the batterys to you should be able to load test them and this will find the problem.
Check all the connections at the alt plugs some connectors burn out. Check for a burnt fusable link on any of the small wires. Gently go along the wires pulling the ends apart if any act like a bungee cord it's burnt.
You should also inspect the wiring behind the passenger side battery. The small red wire coming out of the positive battery terminal that goes to several items on the inner fender is the path from the altenator to the battery.
A couple of months ago I was having starting issues, the batteries tested good but low on charge. The alternator was charging good also. I checked and inspected everything, on the outside it looked OK. Still no start. So I got mad one evening and put a cut off wheel in my 4" grinder. The passenger side positive terminal is where everything electrical joins. I cut the terminal open carefully down to the wires. What a mess it was inside the terminal. The wire was actually eaten off about 1/2" on each of the three wires with corrosion. Cleaned everything up and installed a new terminal and everthing is great now. I did have a hard time finding a battery terminal that would take a 3/0, 2/0 and a #6 wire all together that I could bolt on, but the local Caterpillar dealer had one.
I also had an alternator a couple of years ago that put out 14.1 volts but only 10 amps with the batteries about 75% capacity. If your batteries are low, your alternator should be putting out close to 50 or 60 amps at 2500 RPM, not just 10 amps.