dual batteries drain quickly

there is point that I have NOT seen mentioned
'REVERSE POLARITY'
the camper lights (incadescent) will work no matter if polarity is correct or backwards
water pump and fridge must be correct
but the converter wires or truck wires, might be reverse

there is a heavy drain (not found) or a reverse charging going on

you have done everything except
things like use a portable charger to charge the batteries and test camper wiring

do they batteries go down IF not connected to the truck

yes, camper side wiring
NO, then its the truck side wiring

Either this is a sign of ready for cremation batteries or a pathetically bad electrical path to the batteries. Test the batteries. Then go from there.

Only time problem occurs is when you plug the camper's "7"-pin into the truck's, so there is a short where they connect or farther along in a cable.

When you take a 7-pin apart there are all these wires onto screws around the circle. If strands are loose then one pin's strands can be getting on another's screw. Just one way out of some "possibles".

The main thing is now when camping unplug the camper but remember to plug it back in when leaving so you still have your lights working.

Actually, do they all work properly? If there is a short, maybe not. I suppose like most of us, DW has to go to the back and do the "lights check".

I disconnected the negative cable to the battery of the camper and took my meter and put one lead of meter to the cable and other lead to battery post. Isn't that how you test for a parasitic draw on a battery? Is there a different way I should be testing for a draw on the batteries?

And yes the draw I got of 90ma is not the draw that is causing the problem as it is very tiny draw.

But why is the voltage decreasing when plugged to truck to charge camper battery? The voltage should go up.

shane102.sc wrote:
another test result:

Not sure you have done the ONE test that needs to be done yet.

With everything connected and truck running, measure truck battery.

IF it is above 14 volts but the camper batteries are below 13, then the wiring from truck to camper is NOT right.....or a "battery solenoid" intended to connect the two when the engine is running is not working right.

Battery solenoids are a common point of failure on almost all types or RVs.

clarify .09v difference
or
.09 amp draw
.09amps = 90MA it would take 2000 hrs to drain 200ampHrs of battery

negative post of camper battery disconnected
there is no way to get a power draw from camper batteries

that could only happen with an internal short in a battery

(2) 12volt in parallel one is pulling on the other

another test result: when plugged to truck and truck running and negative post disconnected I get a draw of .09 amps. When not plugged to truck the draw is zero.

mexicowanderer, batteries are good, I have already done all the first steps as in checking condition of batteries. And I have tried 2 other sets of brand new batteries just to check and check again.

shane102.sc wrote:
BFL, I think that is the problem. Here are the results of my tests:

No connections battery volts=12.45, all wires connected=12.38, with shore power=13.20 at battery and at converter= 13.57, here is where it goes wrong I think. Truck battery not running=12.75, when running truck battery volts= 14.87. When I plug camper to truck with truck running the volts = 12.37 and over 5 minutes of running the volts dropped to 12.25. Volts should be rising. Any ideas on what is causing volts to drop when plugged to truck for charging.

Not a clue! Guys who know trucks might. What sort of truck is it? Especially does it have two batteries- one being "auxiliary", and does it have an isolation relay like a Ford does or is the connection open always like with a Chev?

Do you connect with the "camper" one behind the cab or back to the bumper 7-pin? Perhaps there is a short in one of those that acts when you plug in the camper, but is not bothering the normal alternator charging with the truck's own battery when the camper is not connected.

OR--is it the camper's plug??? OR do you have an extension cord that goes from the camper's plug back to the bumper 7-pin, and that is the culprit?

I had the bumper 7-pin go all corroded inside on our Chev. Had to replace it with a standard one. Wiring colours were goofy, but there is a website that shows the different wire colours for Chev, Ford, Dodge 7-pins.