Don't you LOVE electrical problems...

I haven't had a chance to do any testing since I'm on the road right now, but I realized I do have a master DC shut off located in the rear outside compartment of the camper. In this location I'm sure the hot black lead runs from the battery to this simple push pull switch then up to the converter, A round-trip of about 20 feet!

First test I will do will be to disconnect the black leads from that switch and wire them together and see if my voltage changes at the converter.

egarant wrote:
I measured battery voltage at the battery leads on the PD converter. It measures 12.1 vs 12.9 volts that I measure direct to the battery.

When I turn on the heater I measure 10.8 V at the converter and 12.7 V directly to the battery.

Why is the converter 12 V reading so much lower than the reading taken by my inverter and solar charge controller which are wired directly to the batteries?

Easy. Move your voltmeter along the connection between the two. Eventually you will find some point with 12.1 on one side and 12.9 on the other. Tighten, repair, replace, clean, or adjust that component or connection.

One way to figure out which wire has the issue (ground or power) is to probe with your meter and an extension wire. Put the red on the + at the converter and connect the black to a scrap piece of wire that you run directly to your battery -. If you find the voltage is good then the ground wire has the voltage drop and therefore has the bad connection. If not, it's the power side.

From what you measured, it appears that the converter is not connected to the batteries and is only providing TC power. It does not appear that your batteries are powering the TC or you would see a voltage drop there as use increased. The truck appears to be powering the TC when it is connected, so it has to be a power or ground issue off your batteries.

wnjj wrote:
you have a bad connection between your batteries and PD/load center.

Agreed. Check all the connections between batteries and converter.

egarant wrote:
I measured battery voltage at the battery leads on the PD converter. It measures 12.1 vs 12.9 volts that I measure direct to the battery.

When I turn on the heater I measure 10.8 V at the converter and 12.7 V directly to the battery.

Why is the converter 12 V reading so much lower than the reading taken by my inverter and solar charge controller which are wired directly to the batteries?

As has been mentioned several times in this thread, you have a bad connection between your batteries and PD/load center. The only way voltage can be lower at opposite ends of a wire is if there is high resistance for the current its carrying. This is consistent with the higher load of the heater pulling the voltage down even further. When the voltage drops, the current demand goes even higher which probably trips a self resetting breaker.

You need to physically inspect the heavy cables and connections from the batteries to the converter.

egarant wrote:
UPDATE 12/32/14

Last night first night

I'll never get the hang of that west coast lingo...or their calendar.

I measured battery voltage at the battery leads on the PD converter. It measures 12.1 vs 12.9 volts that I measure direct to the battery.

When I turn on the heater I measure 10.8 V at the converter and 12.7 V directly to the battery.

Why is the converter 12 V reading so much lower than the reading taken by my inverter and solar charge controller which are wired directly to the batteries?

Just a guess but it sounds like one of your pieces of electronic equipment have a low voltage setting that is too high or faulty .

UPDATE 12/32/14

I've been camping the past few days in full hookups, everything working fine.

Last night first night off the grid.
Camper unplugged from truck. (isolated)

Batteries show 12.9 volts measured from two different sources that don't fluctuate from these readings, my Xantrex inverter and my Blue Sky solar charge controller, both wired directly to the batteries.

Furnace kicks in during the night and in approx 2-3 minutes the entire camper shuts down, no power. Batteries read 12.7 volts while running the heater and when power goes out. Within 5 minutes the system resets and the heater fan restarts immediately. This cycle will happen continually.

When I plug in the camper to the truck and start the truck the systems run fine and do not shut down. Battery voltage does go up during this tine to 12.9 volts.

This shut down must also be connected to a later post describing my Happi Jac's shutting down the entire camper system after a few minutes. I thought then it was a separate issue, but it sounds very related.

The actions certainly point to a weak battery, but the voltages don't bear it out. Batteries are two 6 month old group 31 Lifeline batteries.

Is my PD converter messed up?