Battery Charging While Trailering

[Booner]

I've searched and searched, PUT and the www, and haven't found what I'm looking for.

I am looking for a write-up on how to charge my PU batteries while trailering the PU.  I have a '99 Chevy Silverado that I pull the PU with, and the PU is a '99 Starcraft.  

Any links to good write-ups or any guidance on how to go about tackling this project will be appreciated.  Thanks!

[wavery]

It's not that difficult. Your truck has a built-in trailer harness with charge line built-in. All you have to do is obtain a factory 7-pin connector.

The one on my '06 Silverado was located up over the spare tire. I think that yours might be there too. It looks like a bundle of wires that are all taped up and the socket has a cap on it. The whole thing was just laying on the back side (toward the rear bumper) of the spare tire itself. You just remove the cap, un-tape the wires, install the factory connector and plug in the factory harness.

I bought a factory trailer hitch from a wrecking yard ($60) and it came with the factory connector attached to the bumper.

[Recumbentman]

Keep in mind that your TV can only maintain your battery level not actually charge your battery while driving. Your alternator on the TV is not strong enough and the wiring going to the trailer is not larger enough to charge a battery.

[AustinBoston]

Keep in mind that your TV can only maintain your battery level not actually charge your battery while driving. Your alternator on the TV is not strong enough and the wiring going to the trailer is not larger enough to charge a battery.

In addition, if there are significant 12V loads on the trailer (I'm mainly thinking of a fridge on 12V) the tow vehicle won't even maintain the charge (though it will slow the rate of discharge).

Austin

[coach]

Be sure and check for voltage at the factory wire bundle.
A 30a or 40a fuse may be needed to activate the charge line.
Fully charged batteries don't need (won't accept much if any) charge.
There is a voltage loss due the the small size wire and length.
Those that have installed a 8 awg don't complain.
Newer Chevys have a new fangled Regulated Voltage Control that require the headlights on or 'tow mode' to activate the RVC into 'charge' mode.

The extreme charging while traveling

Video of wiring istalls at etrailer for chevys
http://www.etrailer.com/tvc-2m-Chevrolet-d-Wiring.html

['tiredTeacher]

Keep in mind that your TV can only maintain your battery level not actually charge your battery while driving. Your alternator on the TV is not strong enough and the wiring going to the trailer is not larger enough to charge a battery.

I respectfully differ.  I accidentally left my frige on 12V (was distracted by neighbor's conversation) and killed the battery. I backed up my Tundra, plugged in, and in a half hour the battery was charged enoght to power lights, water pump and heater for another day.

[aslag]

I respectfully differ.  I accidentally left my frige on 12V (was distracted by neighbor's conversation) and killed the battery. I backed up my Tundra, plugged in, and in a half hour the battery was charged enoght to power lights, water pump and heater for another day.

Same with me, I arrive home with a nearly if not fully charged battery after 4 hours of driving. I'm sure it helps that I don't have the fridge on but in 4 hours it replenishes 4 or 5 days of use battery use.

[tonyw3026]

I did some detailed tests to investigate the charging rate from my TV to the camper. The charge rate is limited by the resistance in the wiring, not by the alternator. The wires are typically 12ga and run from the TV battery all the way to the camper converter and then back to the camper batteries. This is a long way especially when you consider the "round trip" distance ie from  start to finish at the TV battery.

With the standard wiring and set-up the most I could get was about 8 amps with a low camper battery voltage. The amps dropped even lower as the batteries were charged up. This is enough to charge the batteries (slowly) but not with the fridge running because it takes up to 15 amps on its own.

I then ran separate 8ga +ve and -ve wires from the TV battery to a separate plug at the hitch and then straight to the camper batteries. This gives me up to 25 amps charge rate so the batteries are charged even with the fridge running. If we run our 1.8kw inverter on the camper while connected to the TV I actually get up to 55 amps with this set up!! The alternator copes with no problem (Toyota Highlander) and I have a 60 amp fuse at the TV battery - this is OK for 8ga wire.

Tony Wright

[wavery]

I did some detailed tests to investigate the charging rate from my TV to the camper. The charge rate is limited by the resistance in the wiring, not by the alternator. The wires are typically 12ga and run from the TV battery all the way to the camper converter and then back to the camper batteries. This is a long way especially when you consider the "round trip" distance ie from  start to finish at the TV battery.

With the standard wiring and set-up the most I could get was about 8 amps with a low camper battery voltage. The amps dropped even lower as the batteries were charged up. This is enough to charge the batteries (slowly) but not with the fridge running because it takes up to 15 amps on its own.

I then ran separate 8ga +ve and -ve wires from the TV battery to a separate plug at the hitch and then straight to the camper batteries. This gives me up to 25 amps charge rate so the batteries are charged even with the fridge running. If we run our 1.8kw inverter on the camper while connected to the TV I actually get up to 55 amps with this set up!! The alternator copes with no problem (Toyota Highlander) and I have a 60 amp fuse at the TV battery - this is OK for 8ga wire.

Tony Wright

It depends on what you are running on your inverter. 1.8KW = 16A @ 110V AC but that converts to nearly 170A 12V DC.. As long as your camper batteries are fully charged and large enough, you may get away with that for a few minutes.

I have a 2.5KW inverter on my camper. I use "2g" battery cables 3' long and a 175A fuse. There is NO WAY, that I would EVER try to run that thing off my TV alternator with more than a 2-300W load..500W =4.5A @ 110V AC but it is nearly 50A @ 12V DC @ the inverter......with the run up to your TV alternator and back, that is a lot of resistance.

[coach]

I did some detailed tests to investigate the charging rate from my TV to the camper. ...
I then ran separate 8ga +ve and -ve wires from the TV battery to a separate plug at the hitch and then straight to the camper batteries. This gives me up to 25 amps charge rate so the batteries are charged even with the fridge running.

Thanks Tonny for sharing your tests, I've 'heard' this before about 8ga.
Factory charge lines are too small.

There is nothing stopping folks from using a battery between 50-80% like the big rigs do to limit generator use! Eventually they get a complete charge on their batteries when they get somepalce with hookups. Driving hours between campsites with large enough charge line does put some juice back in.

[austinado16]

I get good battery charging, even with the fridge on 12v while towing.

[sorohanbrowns]

I too am able to keep the battery charged while towing with the Fridge on DC. Battery will maintain it's 90-99% charge no problem. I was actually instructed to do this. I am towing with a 04 Honda Pilot. Camping with a 2007 Niagra.