Alternator over charging
Logistics Pro
Joined: Sep 2007
Posts: 3,737
Likes: 179
From: Western Mass
Charge it overnight again with the tender, better than wasting fuel driving around, and letting it idle doesn't really push enough to top them up either.
Try to follow the wires to that other thing, it looks connected to something. May have been for an auxilary battery.
A battery isolator is meant to let multipl batteries charge from one source, but NOT allow them to discharge together. Used in marine and camper situations. So like if you have a battery to run your engine, and a battery to run lights, etc in the boat/camper. Its not a big deal if your lights battery dies, but if your engine battery dies, you're dead in the water. The engine will charge both batteries, the isolator keeps the lights, winch, whatever other load from killing the engine battery.
Try to follow the wires to that other thing, it looks connected to something. May have been for an auxilary battery.
A battery isolator is meant to let multipl batteries charge from one source, but NOT allow them to discharge together. Used in marine and camper situations. So like if you have a battery to run your engine, and a battery to run lights, etc in the boat/camper. Its not a big deal if your lights battery dies, but if your engine battery dies, you're dead in the water. The engine will charge both batteries, the isolator keeps the lights, winch, whatever other load from killing the engine battery.
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Mountain Pass
Joined: Aug 2022
Posts: 161
Likes: 15
Turns out you’re right, it is a battery isolator. The label was always facing away so I never saw it and it was so dusty I never really cared about it. I do have quite a few things that are hooked up direct to the batteries, and the two batteries run to each other but that isolator is not involved. There is one black wire coming from the top but it disappears down under the accessory battery.
Logistics Pro
Joined: Jun 2017
Posts: 3,952
Likes: 509
From: Edmond, OK
Do you just have the two OE batteries for starting the truck, or do you have a third? What accessories do you have running to the batteries? It'd probably be a good idea to find out where that black wire from the isolator goes.
3rd Gear
Joined: Jun 2024
Posts: 3
Likes: 0
Lad, if money is tight, it's going to be tighter when you need to replace both batteries after they get cooked by your sketch voltage regulator. Pull your alternator and have it checked for free at the car parts store. That only costs you time and some fuel. These models seem to throw a lot of heat in the alternators with built-in voltage regulators which kills the diodes. Then the alt starts overcharging, cooks your batteries and the batteries lose cells and the voltage drops, then your truck blacks out. There is no computer here to help you (and no computer to get fried from the overcharge thankfully ) but we are here and I am telling you because I learned the hard way.
Tuned
Joined: Jun 2002
Posts: 353
Likes: 1
I have a 91 IDI and my truck was charging at almost 19 volts. I changed the regulator took the alternator to a repair shop and they said it was good.
I had a good Ford 3G alternator laying around so I changed the pulley and installed it and got rid of the external regulator and it is charging fine now.
I had a good Ford 3G alternator laying around so I changed the pulley and installed it and got rid of the external regulator and it is charging fine now.
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