Power draw from TV?

[agoodhi]

Hi,

When the trailer is plugged into the tow vehicle (not running), I noticed my brake controller is lit up. Is the trailer drawing any power from the TV batteries while connected?

I usually unplug the hookup to the TV just in case, but wasn't sure if it is really necessary.

--Ryan

[LadyWindrider]

Depends on your tow vehicle and how it's wired. Ford trucks use a relay that only connects the two together when the switch is in the "on" position. Not all have this feature. Some use an isolator diode, some may be wired together. All of these are so the tow vehicle will charge the trailer batteries going down the road. You don't want the two connected together when the tow vehicle is "off", so you won't run down your tow vehicle battery along with your trailer battery. As for the brake controller being lit, is normal, and should be lit when plugged in. This is an indication that you are plugged in correctly and you should have trailer brakes. No light equals no trailer brakes.

[KyDan]

As stated it might be possible to run down your tow vehicle battery
along with your trailer batteries if you're boondocking.

As a side note, my truck battery will run down just sitting in the
garage for a month. I have a little car I drive every day and it's
not unusual for my truck to sit between towing episodes.
I've discovered the hard way that it will not start after 4 weeks
of storage. 3 weeks yes-- 4 no way.
I use a prodigy brake controller and someone on another chat group
says the controller slowly drains your battery even if the trailer
is not plugged in. He unplugs the prodigy when not needed.
(The prodigy has a mount that allows you to remove it from the
vehicle if wanted.)
I don't bother.
I just got a battery tender and plug it in when the truck is
in the garage.
It's always ready to go that way.
If you drive your tow vehicle on a regular basis this is not an issue.

Battery tender jr. is about $25.
You can get a knock off version at Harbor freight for $6.

[MtnGuy]

Originally Posted by agoodhi

Hi,

When the trailer is plugged into the tow vehicle (not running), I noticed my brake controller is lit up. Is the trailer drawing any power from the TV batteries while connected?

I usually unplug the hookup to the TV just in case, but wasn't sure if it is really necessary.

--Ryan

Get a 12v test lite, and hook it up at the 12v power (11 o'clock position) and the ground (5 o'clock position) on the bargman connector on your truck, and see if you have power with the key in the off position. If you don't, then you have the isolater switch on your truck, and you don't have to worry about the trailer pulling the battery down during a prolonged stop.

http://www.hitchntrailer.com/pages/elect.html

You can also hook a jump wire on the trailer side of the bargman between the 12v (1 o'clock position) and the tail lites (11 o'clock position) to have an impressive display of your running lites at the campground.....with hookups, of course. I have a fused jumper for this.....just in case I mess up.

The minimal power draw of the brake controller should not run the battery down unless it was for a prolonged stop......maybe days.

[LadyWindrider]

The brake controller has minimal effect on drawing the battery down. These days with remote entry, memory in radios, clocks, keep alive memory in the engine computer, memory seats,..... all these require power all the time. Not unusual for a battery to die after 30 days, without a brake controller. Detroit figures we buy em to drive em, not park the, and look at them.