Factor Dual Battary - 2003 1500hd 6.0l

opc167 · April 28, 2011

I need help also. I have a 2003 1500HD with a factory dual battery setup (it's funny how people thank I'm crazy when I tell them it's not a diesel). I need to give you my scenario for advice please. I do not have extra accessories such as lights, winches, etc., just the regular factor towing package and running lights. What happen is, I started having problems cranking the truck after I would sit in the truck with the radio on for 20 – 30 minutes and required me to jump it off. About the 3^rd occurrence, I went to jump off the truck and the auxiliary battery was fried…very hot. I un-hooked the auxiliary, jumped the main, and all was fine. The auxiliary is not giving me any problems but I'm still having to jump off the main battery on occasion. The main battery shows 12.4 while not running and about 13.5 – 13.8 while running. A few questions: Can you jump the main battery from the auxiliary if I have issues with cranking? Also, is this factory setup also charge this auxiliary in parallel with the main? When I disconnect the auxiliary, I cannot find anything that will not work on the truck. I'm thinking of removing the auxiliary and place it as the main, but it is smaller!!! Where do you hook up auxiliary devices to this 2^nd battery? From the factory setup, what would cause the 2nd battery to go bad?

Hope someone can help. Regards, Chris Brooks – Macon Ga.

8.1HD/ALLISON · April 28, 2011

Im not sure how they are run from the factory. The diesels are run in parallel with no isolator. I would follow both cables and see if there is an isolator. I would then disconnect both batteries and have them tested. 30 mins of radio should not kill a battery. As far a connecting to aux battery, if there is a junction block go there, if not hook back to the battery connection. Be sure to fuse any circuits.

builderpaul · April 28, 2011

I need help also. I have a 2003 1500HD with a factory dual battery setup (it's funny how people thank I'm crazy when I tell them it's not a diesel). I need to give you my scenario for advice please. I do not have extra accessories such as lights, winches, etc., just the regular factor towing package and running lights. What happen is, I started having problems cranking the truck after I would sit in the truck with the radio on for 20 – 30 minutes and required me to jump it off. About the 3^rd occurrence, I went to jump off the truck and the auxiliary battery was fried…very hot. I un-hooked the auxiliary, jumped the main, and all was fine. The auxiliary is not giving me any problems but I'm still having to jump off the main battery on occasion. The main battery shows 12.4 while not running and about 13.5 – 13.8 while running. A few questions: Can you jump the main battery from the auxiliary if I have issues with cranking? Also, is this factory setup also charge this auxiliary in parallel with the main? When I disconnect the auxiliary, I cannot find anything that will not work on the truck. I'm thinking of removing the auxiliary and place it as the main, but it is smaller!!! Where do you hook up auxiliary devices to this 2^nd battery? From the factory setup, what would cause the 2nd battery to go bad?

Hope someone can help. Regards, Chris Brooks – Macon Ga.

From the factory a non diesel will be an isolated set up. (RPO code 8B0). If you have it with the factory trailer package (RPO Z82) than the power to the trailer comes from the isolated battery. Your truck stuff (radio etc) all run off the main battery.

The isolated is used for aftermarket stuff like inverters, or high power stereos. You hook them up to the aux battery. (fused off course)

They only time both are connected is when there is power from the alternator. They both charge at this time. If the truck is off than they are seperate.

Yes you can jump the main from the aux. Just need one cable from positive to positive. (grounds are tied together already)

The isolated is a smaller CCA battery but the same dimensions as the Main. It also has a shorter warrenty period.

I just changed the batteries on my 04, the aux was bad but the main was still good. I replaced with 2 the same size (820 CCA)

If you still have the original batteries in your truck they probubly are both bad. The main discharging to fast with your radio useage and the aux with an internal short drawing too much charging current.

opc167 · April 28, 2011

I need help also. I have a 2003 1500HD with a factory dual battery setup (it's funny how people thank I'm crazy when I tell them it's not a diesel). I need to give you my scenario for advice please. I do not have extra accessories such as lights, winches, etc., just the regular factor towing package and running lights. What happen is, I started having problems cranking the truck after I would sit in the truck with the radio on for 20 – 30 minutes and required me to jump it off. About the 3^rd occurrence, I went to jump off the truck and the auxiliary battery was fried…very hot. I un-hooked the auxiliary, jumped the main, and all was fine. The auxiliary is not giving me any problems but I'm still having to jump off the main battery on occasion. The main battery shows 12.4 while not running and about 13.5 – 13.8 while running. A few questions: Can you jump the main battery from the auxiliary if I have issues with cranking? Also, is this factory setup also charge this auxiliary in parallel with the main? When I disconnect the auxiliary, I cannot find anything that will not work on the truck. I'm thinking of removing the auxiliary and place it as the main, but it is smaller!!! Where do you hook up auxiliary devices to this 2^nd battery? From the factory setup, what would cause the 2nd battery to go bad?

Hope someone can help. Regards, Chris Brooks – Macon Ga.

From the factory a non diesel will be an isolated set up. (RPO code 8B0). If you have it with the factory trailer package (RPO Z82) than the power to the trailer comes from the isolated battery. Your truck stuff (radio etc) all run off the main battery.

The isolated is used for aftermarket stuff like inverters, or high power stereos. You hook them up to the aux battery. (fused off course)

They only time both are connected is when there is power from the alternator. They both charge at this time. If the truck is off than they are seperate.

Yes you can jump the main from the aux. Just need one cable from positive to positive. (grounds are tied together already)

The isolated is a smaller CCA battery but the same dimensions as the Main. It also has a shorter warrenty period.

I just changed the batteries on my 04, the aux was bad but the main was still good. I replaced with 2 the same size (820 CCA)

If you still have the original batteries in your truck they probubly are both bad. The main discharging to fast with your radio useage and the aux with an internal short drawing too much charging current.

O.K. I see now. That's why everything worked but I didn't test the trailer hookup. Pos to Pos makes since also. I didn't want to fry them with an attempted jump. The main has to be going bad.

Thanks again.

markw8 · April 29, 2011

If you jump from the aux. to the main, I think you should use both cables. I don't think the ground from the aux. is large enough by it's self.

Also, the only time the aux. battery is being used is with the key in the run position. Regardless wether the truck is running or not. If you are using power in the camper with the key off but plugged in, it's drawing from the main starting battery. I found this out on my first trip with my camper and my 2000 Silverado.

Mark

builderpaul · April 29, 2011

If you jump from the aux. to the main, I think you should use both cables. I don't think the ground from the aux. is large enough by it's self.

Also, the only time the aux. battery is being used is with the key in the run position. Regardless wether the truck is running or not. If you are using power in the camper with the key off but plugged in, it's drawing from the main starting battery. I found this out on my first trip with my camper and my 2000 Silverado.

Mark

Something was not right with some connection to you trailer was it factory trailer and factory isolated?

Isolated is made to be used key off. I use an inverter everyday hooked to the isolated and truck off. I have run the isolated down but never the main.

I run my camper all night, pluged into the truck. Never a problem with starting.

Key on connects the 2 batterys together so the isolated will charge.

markw8 · April 29, 2011

Nothing was wrong with the truck. It was as designed and built. At some later point I believe the design was changed. The aux. battery was to help power snow plow equiptment and high draw electronics, while the truck was running. The power wire in the trailer wireing harness, was powered off the main/starting battery. The wiring under the hood had to be changed to draw from the aux. bat. with the key off.

This was ass-backwards from what everyone thought. I forgot and left my fridge running on battery when I stopped in a Virgina rest areato sleep 4-5 hours. I also mistakenly thought it only drew 5 amps per hour, not the 20 it did. After 5 hrs it had to be jumped. Ford wired thier's the logical way.

I think the only reason for them being isolated with the way they are wired, is to stop them from self discharging while the truck sits.

Mark

rtb1259 · May 3, 2011

I have heard it is recommended to change both at the same time. Preferably from same lot and build date. The reason is that different batteries can draw down each other.

This is what I used to add accessories. It is a new fuse block I found, and built the way I wanted. 8 relays and 12 fused circuits. This gave me plenty of space for anything I want to add.