Dual Battery Question

bruceb58 · Friday at 08:50 PM

2 hours ago, jake111 said:

Well, officially "smart" or not, when I hooked up my slide-in camper to the trailer 7-way, I immediately noticed a BIG difference in the way it charged the house battery. Or maybe I should say, how it didn't... I was sitting in park and the alternator was putting out well under 13 volts, too low to trip the camper separator, so no charging. Yes, I revved it up. No, it didn't help. I saw the voltage varying quite a bit. I know of no "unsmart" alternator that behaves like this. Certainly, none of my older cars and trucks did this.

In order to get my alternator to kick up to a high enough voltage to enable my DC to DC converter to start, I momentarily turn headlights on and off. Once the alternator sees the load of the converter, it stays in high voltage mode.

If the truck is still in its high voltage mode after a startup, it will start up the DC to DC fine.

Yes...it's a smart alternator. If it wasn't, it wouldn't be having this behavior. My F150 did the exact same thing.

revrnd · Saturday at 02:15 AM

OK, I found what I was looking for...

In 1980 the RPO V10 Cold Climate Pkg consisted of:

C42 - HD Heater & Defroster

K05 - Block Heater

UA1 - HD Battery

jake111 · Saturday at 02:19 AM

7 hours ago, revrnd said:

Is that thru the plug on the LH side boxside or the 1 on the bumper?

In the camper I changed the plug from the left front area to the rear so I could just use the 7-way in the bumper. LH front in the box requires cutting a hole and mounting in bed, which I did on my old truck, and which was a pain to reach the plug when necessary.

jake111 · Saturday at 02:24 AM

5 hours ago, bruceb58 said:

In order to get my alternator to kick up to a high enough voltage to enable my DC to DC converter to start, I momentarily turn headlights on and off. Once the alternator sees the load of the converter, it stays in high voltage mode.

If the truck is still in its high voltage mode after a startup, it will start up the DC to DC fine.

Yes...it's a smart alternator. If it wasn't, it wouldn't be having this behavior. My F150 did the exact same thing.

Yes, I think I panicked when I first hooked up and was getting erratic voltages. Seeing the alternator drop well below 13 volts I was afraid I really toasted something. In practice, it does start charging and then is fine. I even returned the DC-DC charger because I don't think I need it (until I want to switch to lithium). I now have a Scangauge showing more precise voltage levels and on the last outing everything looked good.

Edited Saturday at 02:25 AM by jake111

revrnd · Saturday at 02:43 AM

21 minutes ago, jake111 said:

In the camper I changed the plug from the left front area to the rear so I could just use the 7-way in the bumper. LH front in the box requires cutting a hole and mounting in bed, which I did on my old truck, and which was a pain to reach the plug when necessary.

I didn't realize there is a plug @ the front. I was going by the plug on my brother' truck. His has the 5th Wheel/Gooseneck Provisions. My truck w/o it has a plastic filler plug.

bruceb58 · Saturday at 05:56 AM

3 hours ago, jake111 said:

Yes, I think I panicked when I first hooked up and was getting erratic voltages. Seeing the alternator drop well below 13 volts I was afraid I really toasted something. In practice, it does start charging and then is fine. I even returned the DC-DC charger because I don't think I need it (until I want to switch to lithium). I now have a Scangauge showing more precise voltage levels and on the last outing everything looked good.

When you do get a DC to DC converter again, get the Victron Orion XS 50A. You will need to run heavier wires though. I know you had the 30A before but the Orion XS is so superior in many ways when you want to charge lithium. I have 560AH of lithium in my trailer.

Edited Saturday at 05:58 AM by bruceb58