Well, I think I got it figured out.

The batteries were so discharged that due to the difference of potential the voltmeter only showed 12 volts. Once I disconnected the battery cable I got 14.2 volts.

It did keep a charge of just under 12 volts, say 11.96, since I parked it on Thursday afternoon.

Right with the WFCO manual, I saw 13.2 and 13.6 volts when charging.

I let it charge for a couple of hours and ran the air conditioning while I did a little clean up inside.

I unplugged from 110, then rechecked the battery voltage, it was 12.7, so I'll leave it for a week and check it again.

 

Okay, I got that. So when you said in your initial post your batteries needed charging you were dry camped with no shoreline connected? Now here is where I am confused. You ran your truck for several hours and the batteries hardly came up. Were they really down then before you hooked up? I thought you were running a shoreline while camped in your initial post.

Steve

 

I think people underestimate how long it takes to charge a deep cycle battery. I know I sure did back when I first got mine.

The other thing is that some "smart" chargers don't like to charge at high rates for too long. I have one that shuts down on error after a certain number of hours if it doesn't see the battery voltage increasing enough. Easy fix is to unhook and rehook it. I wish there was a setting on my charge to tell it that it's dealing wth a deep cycle. Maybe my charger isn't as smart as it thinks . . .

 

I was dry camping, no generator, no hookups. I guess the batteries were in such a state of discharge that the truck just didn't have enough to go through the 7 wire.

 

Man, that severe a discharge is no good for the batteries.

But now it all makes sense.

Steve

 

I'll be on top of it better from here on out.

 

I don't think you fixed it yet. You just measured 13.2- 13.6 while on shore power but your original issue was the charging system while hooked up to your truck.

What is the battery voltage connected to your truck when running? Before you said it was 12.08 volts. That meant your weren't getting any charge from the truck. So we know your WFCO converter is working while getting 110v from shore. Btw, I would check the two fuses at the base of your converter, probably 40-45amp fuses and carry a few spares. Your converter can charge up to 14.2 volts if the batteries are that drained.

When I blew mine out, it created havoc, not charging my batteries with the generator running. That lead to a low battery voltage which wasn't high enough to trip the switch and power spark for the generator. (I always thought the spark for the generator was created with a magneto or CDI ignition like many small motors. Nope.)

Did you inspect your truck/trailer connector? You might also check your ground connection on the trailer side. Try hooking your trailer up to a buddy's rig and test just to validate your circuitry.

 

If new batteries were discharged to only 12.08 volts, the truck will charge the batteries. You should expect a static battery to show about 12.8-9 volts and your's are low but not catastrophic. Discharged batteries won't create a situation as you describe above. Impossible to Ohm's Law.

Your truck might create too much heat, trying to charge the batteries, that you might blow the fuses under the hood but that's not probable.

Again, find a buddy and test with his rig. I don't think you're done yet.

 

Bob, wasn't it 12.08 after several hours of charging using truck? Of course at about 10 volts propane detector should have been singing and module boards should have been shutting down.

Steve

Steve

 

Steve, he never said he hooked it back up to his truck. In fact, the charging only occurred using shore power as noted when his WFCO showed 13.2-6 volts.

I went back and read carefully but maybe I missed something but I don't think so.

What post clarifies that if you would.

 

With the truck 7 wire connected, but the trailer batteries disconnected, I read 14.2 on the meter at the battery cables.

When I reconnected the batteries, the meter showed 12.2. This proves to me that the truck is trickle charging the trailer.

The only reason this is an issue is because of our last tent trailer. I could hook up and go with a dead trailer battery and by the time we reached our destination, the battery was good to go for the duration of the trip. Mind you, it was a single 12v deep cycle vs the dual 6v in my current trailer.

I just thought the truck would charge the trailer batteries quicker than it did.

 

With my setup I have a dedicated heavy line from the truck battery through a relay that shuts off if the volts up front get too low, the relay also stops the front battery from drawing from the rear at start up. Similar to this one.

Ive never had an issue with a flat trailer battery.
Plus also, the trailer has a solar panel to keep it all charged when off the truck.

 

Does the trailer battery use and isolator so they dont drain back from the truck, those battery isolators, lose voltage across the terminals, I have seen a drop of 2 or 3 volts, just in the isolator. Check that aswell.

 

Mine has a charge relay. No power to the 7 wire charge lead unless the key is on.

 

I believe that is true of all the trucks. The only place I have seen an isolator used is in the "B" van campers.

I add a manual disconnect on all our towables being too lazy to disconnect the trailer battery lead when it is stored.

Steve