I have not been able to get a good charge to the camper house batteries using the truck alternator. I have the dual 105 amp alternator option on my 2004 Duramax for total of 210 amps of potential output. It seems like the regulator is sensing that the truck batteries are charged and it reduces the current output so that the camper batteries only get a trickle.Has anybody else found a way to get around this problem and allow the camper batteries to get a full charge from the alternators while driving?

Here is my setup with my 06 Dmax. Includes 2 gauge wire for both hot and ground. If you're using the stock charge wiring, the wires are most likely too small to ever get a full charge (too much voltage drop). You could measure the voltage at the camper batteries to be sure -- should be over 14v minimum.

cewillis wrote:Here is my setup with my 06 Dmax. Includes 2 gauge wire for both hot and ground. If you're using the stock charge wiring, the wires are most likely too small to ever get a full charge (too much voltage drop). You could measure the voltage at the camper batteries to be sure -- should be over 14v minimum.x2 - you've probably got a long piece of thin wire going from the truck battery possibly all the way to the back of the truck, then through a connector to the camper and another thin wire that runs all the way to the front of the camper where the battery compartment is. = a plenty of voltage drop - not enough voltage to fully charge the battery. So first job I suggest is to upgrade to heavy-gauge wire to minimize that voltage drop.Steve.

Make sure the fuse or relay is in place in the under hood fuse box for trailer accessory power. Mine wasn't and I did not realize until the fridge and trailer brakes started acting up due to a dead trailer battery.

If you're using the stock charge wiring, the wires are most likely too small to ever get a full charge (too much voltage drop). You could measure the voltage at the camper batteries to be sure -- should be over 14v minimum.X3!!I regularly see charge current over 50A @ 14.7V (and occasionioally/briefly over 100A)Cheers-Mark

Good to see the fuse there! You have one on the other end too, right?

Charging the camper batteries with the truck motor

DWeikert
Explorer II
Jul 29, 2014
Good advice above but even with the stock light wiring you should still be able to charge the camper battery, it will just take a little longer. As the camper battery charges it will reduce the current flow through the charge wire and reduce the voltage dropped across that wire until the battery is fully charged. Unless you have another DC load in the camper causing a voltage drop across the charging wire. For example, running an absorption fridge on DC can keep enough current flowing through the charge path that the voltage drop from the charge wires never allows the battery to get the full charge. Make sure other DC loads in the camper are turned off and you should be able to charge the camper battery. But keep the wiring upgrade on your "to do" list.
Golden_HVAC
Explorer
Jul 29, 2014
msiminoff wrote:
If you're using the stock charge wiring, the wires are most likely too small to ever get a full charge (too much voltage drop). You could measure the voltage at the camper batteries to be sure -- should be over 14v minimum.

X3!!
I regularly see charge current over 50A @ 14.7V (and occasionioally/briefly over 100A)

Cheers
-Mark

Yes this is the size connector to use when you want to get that power from the truck to the trailer. Make sure that you are also using a high quality relay, so that you do not drain the truck battery when using the furnace at night while still plugged into the truck.

Grainger part # 6C 017 has silver allow contacts, and is rated at 100,000 on and off starts with 100 amps going through it! That should last the life of the truck and another dozen more!

It will also improve the ground wire - so your brakes might work better too. You might also want to upgrade the braking wire from the battery to controller to #10 wire and also controller to trailer connection to #10 wire. IT is designed to carry up to 12 amps for 4 brakes or 18 amps with 6 brakes, yet most trucks have a #14 wire to carry all that amperage, with voltage loss can lead to only 9 amps going to the brakes on a dual axle set up. THis was a recent post today about brake improvement!

Fred.
stevenal
Nomad II
Jul 28, 2014
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/14538077/gotomsg/14541188.cfm#14541188
wintersun
Explorer II
Jul 28, 2014
All that is needed for the short run from the engine compartment to the receptacle in the bed of the truck is 8ga wiring for the power and ground lines. You can use thicker gauge but it is not going to make a measureable difference in charge times.

You may also have a failing alterntor with your truck. Easy to get it checked out in terms of output. Second component that can cause problems is the voltage regulator. Third possibility is a failing battery in the camper or in the truck. A bad cell creates added resistance in the circuit.
DiploStrat
Explorer
Jul 28, 2014
GoFish wrote:

It seems like the regulator is sensing that the truck batteries are charged and it reduces the current output so that the camper batteries only get a trickle.

That is exactly what is happening.

Has anybody else found a way to get around this problem and allow the camper batteries to get a full charge from the alternators while driving?

Yes, my 2013 Chevrolet with 2x125A alternators routinely shows a charge rate, measured at the camper batteries, of over 150A.

Shoot me an e-mail and I will send you two papers that will show you one way to achieve the same sort of performance.
HMS_Beagle
Explorer
Jul 28, 2014
Good to see the fuse there! You have one on the other end too, right?
msiminoff
Explorer II
Jul 28, 2014
If you're using the stock charge wiring, the wires are most likely too small to ever get a full charge (too much voltage drop). You could measure the voltage at the camper batteries to be sure -- should be over 14v minimum.

X3!!
I regularly see charge current over 50A @ 14.7V (and occasionioally/briefly over 100A)

Cheers
-Mark
kevden
Explorer
Jul 28, 2014
Make sure the fuse or relay is in place in the under hood fuse box for trailer accessory power. Mine wasn't and I did not realize until the fridge and trailer brakes started acting up due to a dead trailer battery.
sabconsulting
Explorer
Jul 28, 2014
cewillis wrote:
Here is my setup with my 06 Dmax. Includes 2 gauge wire for both hot and ground.
If you're using the stock charge wiring, the wires are most likely too small to ever get a full charge (too much voltage drop). You could measure the voltage at the camper batteries to be sure -- should be over 14v minimum.

x2 - you've probably got a long piece of thin wire going from the truck battery possibly all the way to the back of the truck, then through a connector to the camper and another thin wire that runs all the way to the front of the camper where the battery compartment is. = a plenty of voltage drop - not enough voltage to fully charge the battery. So first job I suggest is to upgrade to heavy-gauge wire to minimize that voltage drop.

Steve.
cewillis
Explorer
Jul 28, 2014
Here is my setup with my 06 Dmax. Includes 2 gauge wire for both hot and ground.
If you're using the stock charge wiring, the wires are most likely too small to ever get a full charge (too much voltage drop). You could measure the voltage at the camper batteries to be sure -- should be over 14v minimum.

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Charging the camper batteries with the truck motor

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