Battery Drain When Travelling - Power Converter Issue?

[mjlaupp]

Originally Posted by SirDrake

....Next, I disconnected the Tow Cable from the TM (I opened the side compartment on the TM and untwisted the wire nuts connecting the Tow Cable's positive and negative lines).
With the truck running and plugged into the TM tow cable, the reading at the ends of the cable (bare wires) I get approx 13.5 volts. So voltage is passing through the Tow Cable from the truck no problem.....

13.5 volts is a normal reading with no load on the circuit. Add a load (converter) and you get:

....If I connect the positive cable from the Tow Cable to the positive cable that goes to the on board Power Converter, the reading drops to 1.5 volts!!!.....

You have a bad connection or corrosion on the 12 volt line between the TV battery and the point where you are measuring voltage. Does your Avalanche have a battery isolation device? My first suspect area would be at the 7 pin connector.

[mjlaupp]

Originally Posted by mjlaupp

....You have a bad connection or corrosion on the 12 volt line between the TV battery and the point where you are measuring voltage.....

Try connecting the TV battery to the converter wires at the fridge connection using battery jumper cables to test for this.

[SirDrake]

OK. I think I have solved the problem.
I am now getting 13.5 volts at the connection on the Power Converter (where I was getting 1.5 volts previously).

After reading all the advice you guys posted, I started looking into those areas you pointed out.
I had replaced the connector on the back of the truck so I know that is good.
I also cleaned and tested the end of tow cable on the TM - so I know that is good.
While troubleshooting this issue this weekend I also opened all the wire nuts in the refrigerator compartment on the side of the TM.
They were all in good shape - no corrosion etc (I replaced all wire nuts here a few years ago anyway).

So then I started looking at all the ground points on the Avalanche.
I found a broken ground strap between the hood and the firewall - I cleaned and repaired it.
Cleaned the ends of the ground cable from the engine block to firewall.
The underside of the truck is very rusty, so I located all the ground points I could find - about four in all.
I used PB Blaster on all ground points then I removed the bolts and scrubbed everything with a wire brush, then I reconnected them.
After that I began to look for ground points under the TM.
The only connection that looked suspect was one of the gray water tank probes - it was rusty and corroded.
I disconnected it and scrubbed it with a wire brush and replaced.
That was it.

I left the TM battery disconnected, plugged in the Tow Cable and started the truck.
Put the meter on the positive and negative block on the Converter and to my surprise it now reads 13.5 volts!
I reconnected the TM Battery and tested again - 13.5 volts and holding.

In addition, I managed to fix another important issue while investigating all this.
I found that the power lead to the safety breakaway cable for the brakes had been severed at one point along the frame!
Not sure how that happened, perhaps it has been like that since I bought it, but in any event I reconnected the line so all is well.
I suppose I should test it. Another day....

Thank you to everyone who helped out with advice. It is much appreciated.
Our next trip is in August to the Thousand Island region in upstate NY - about a 4-5 hour trip.
I will post here the results of running the fridge and cooler.
Hopefully it goes well.

~ John

[TM Pilot]

That the grounding points on your TV were corroded and causing the low voltage instead of the grounding points on the TM makes sense since the TM battery didn't charge via the TV but did charge when connected to shore power.

Low voltage is often caused by a corroded ground, therefore it is a good place to start the troubleshooting process. My electric tongue jack stopped working because of low voltage due to a corroded ground through my swing hitch. Once I cleaned it, it worked great.

Good work, John! Glad your TM issues have been resolved. And nice catch on the breakaway cable power lead. Having a fully charged battery while towing wouldn't mean a thing during a breakaway if the power lead is disconnected! Looks like your charging issue was a blessing in disguise.

[SirDrake]

Yeah, I think it was Jerry who pointed out the positive and negative buss and that everything grounds to the frame on the TM and TV.
Started to make sense that if there was a bad ground it would cause the low voltage, but was not obvious to me at first; especially that it would be the TV.
Not sure which ground it was on the Avalanche, but I think I fixed them all (including the broken strap to the hood).
It was pretty rusty on the underside, not surprised if there was a bad contact there.
And like you said, I found the broken breakaway cable so I guess it was all worth it.
Thanks again for all the help guys.

~ John

[Bailey'sMom]

I would love to see some close up pictures of the ground wires and their location on the TM. I keep hearing about checking for bad grounds, but honestly don't think I would know one if I saw one.

Thanks

[scrubjaysnest]

On your SD they should be in the same place as our SL. That is Street side between the rear bumper and the gray water discharge is a black plastic cover with a screen in it. Remove the cover and the frame grounds are there.
Sometimes there is an odd one along the frame such as the electric tongue jack or under the break away break switch.

[Bill]

Bailey's Mom -

In my 2720SL, the battery is in the rear compartment. On the battery's negative post, there are two wires - one white and one bare (might also be green on some trailers). The bare wire is the primary ground, and runs to a connection on the frame only a couple feet away from the battery. The white wire runs up to the converter, where it terminates at the ground "buss bar" inside the converter housing. There is another ground connection from that buss bar to the frame somewhere up there. But the bare wire is the main one.

In addition, every light has two wires, hot and ground. The ground wire is simply screwed to the aluminum skin of the trailer right at the fixture, and since the aluminum skin is attached to the frame, the light circuit is completed this way. When a single light doesn't work, a loose ground at the fixture is often the culprit.

But the primary ground for the entire system is the bare wire at the battery.

Bill

Originally Posted by Bailey'sMom

I would love to see some close up pictures of the ground wires and their location on the TM. I keep hearing about checking for bad grounds, but honestly don't think I would know one if I saw one.

Thanks

[DoubleT]

I have 1 2008 2619 and need some clarification. Does TM come with a converter or an invertor? Help me understand the difference and the purpose/job each does. Thanks from an electrically challenged owner.!!

[YNPKing]

This is my first post. I enjoy reading all the information in the forum. It is an excellent source of information. I hope this question hasn't been answered.

My question is, how much amperage is supplied to the battery from the TV? I have 2 6V Lifeline AGM batteries supplying 220V inside my 2417 Sport. When traveling, I run the fan and refrigerator on DC. I was told by Dometic that the refrigerator on DC consumes 15.0 amp/hrs and I'm guessing about 1 amp/hrs for the fan. So, about 16.0 amp/hrs is withdrawn from the batteries. Will the TV offset the 16.0 amp/hrs? Does the Bargman and/or trailer wiring suppress the amperage to the WFCO converter? Does the converter itself suppress the amperage to the batteries? I'm thinking that due to the size of the trailer wiring to the converter, it can only carry a few amps.

The reason for my question is that when I arrive at the campsite after traveling 6-8 hours and connect to AC, the converter fan runs for a period of time (?) which makes me think the batteries require a significant bulk charge.