TV wiring too small ??? Bill's test method:

[rickst29]

Hi y'all. I asked Bill in a private message whether he'd ever built a fancy TV-bargeman-connector-to-TV-connector for making electrical measurements, and he hasn't. But he's got a GREAT recommendation for testing how much the load from your TM fridge drops the voltage at the TV connector socket under load.

First, let me remind you of the 'testing' problems. Inside the TM, all the electrical wiring is #10 (very heavy, able to handle big loads with very little voltage drop). But when the reefer 's running on 12V (while towing), TVs with thinner wires, or with lots of terminals in the path to/from the bargeman connector, might not be able to deliver good current AND maintain a good voltage differential. And that means 2 things: (1) Your're not providing proper voltage to the reefer, so it's sucking on the TM batteries for the rest; (2) you're simply wasting a lot of electrical energy as heat in the undersized TV wiring.

Of course, if you're discharging the batteries to run the reefer, you're certainly NOT charging them from the TV... this is bad if you're headed to a boondocks location.

If you measure the +12V and Ground at your TV socket, without the TM reefer drawing on it, you'll see about 13 volts (it'll more or less match the battery/alternator voltage if nothing's connected). You need a way to get at the leads while the TM reefer is running.

Here's Bill's suggestion:

Get yourself a piece of tin foil, about 1" wide by 2" long. Fold it in half the long way, so it is 1/2" x 2". Fold it in half again, in the same direction - now it is 1/4" wide x 2" long, and several layers thick. Now make a second identical piece.

In the trailer half of the connector, identify the +12VDC and ground slots, and push one of your pieces of foil into each one. Fold the protruding ends of the foil back against the body of the connector.

Back the tow vehicle up near the trailer tongue, but not touching it. Mate the two halves of the connector as if you were getting ready for travel. The foil "wings" stick out of the connector, so you can touch voltmeter probes to them, and determine what voltage you have under various conditions.

Start the tow vehicle engine, turn off the refrig, and measure the voltage. Turn on the refrig, and measure the voltage. Put the hitch on the hitch ball, measure again, etc. Measure the voltage from the ground pin of the connector to the trailer frame near the hitch. Rev up the engine, etc.

Hope this helps. It is an easy way to measure voltage at the point in question. By the way, under each test condition, I also measured the voltage at the distribution point which, in my 2720SL, is under the kitchen sink. And I also measured it at the tow vehicle battery. It showed me that, in my rig, almost all of the voltage drop is in the tow vehicle wiring between the battery and the Bargman, and much less of it is in the TM wiring.

At the time, I had also thought about building a much more elaborate test box, which would have digital readout of both the voltage and the current in all six circuits that pass through the Bargman connector. It would also exercise the brakes, check for bad grounds, and so forth. I designed it on paper, but it started looking pretty expensive, and I learned to live with the problem, so it never got off the ground.

Obviously, you need to keep your foil tabs away from other leads. And you should be careful connecting and disconnecting, otherwise you'll have torn foil left behind. Be careful !!! The attached photo shows the bargeman connector pinouts.