Charging RV batteries with TV

I made a set of jumpers out of 00 gauge welding leads about 25' long with some good $70 clamps from NAPA. they are heavy but work very well.

My neighbor lost the house batt in his 5th wheel in the middle of the night. Temps in the teens. Plugged the cord into the truck. It ran the furnace all night and the next day we drove into Flagstaff and he got a new batt. He had a gen but the truck was much quieter and he did not want to wake up the others due to having a commercial type (loud) gen.

Robin1953 wrote:

jalichty wrote:
At one point in time, quite a while ago, I talked to a guy who was running his TV and had plugged in his FW to charge it. I have not done that, but wondered if it would work since the truck does charge the battery as you are traveling down the road. Maybe that would work for you. If it would, you wouldn't have to worry about jumping from the truck battery to the FW battery.

I did that when I had my F350. Didn't take long to run the charge back up on the TT battery.

I would assume the charge current is much, much lower using this method vs. directly charging a battery with large gauge jumper cables. The wire in these wiring harnesses use relatively small gauge wire, not to mention the extra resistance incurred because of the long distance (probably more than 20 ft.) from the TV's alternator to the TT's battery.

Jumper cables should be a minimum of TWO GAUGE copper. Take your time and don't get the polarity crossed.

Motorhome charging systems have to do this duty all the time.

jalichty wrote:
At one point in time, quite a while ago, I talked to a guy who was running his TV and had plugged in his FW to charge it. I have not done that, but wondered if it would work since the truck does charge the battery as you are traveling down the road. Maybe that would work for you. If it would, you wouldn't have to worry about jumping from the truck battery to the FW battery.

I did that when I had my F350. Didn't take long to run the charge back up on the TT battery.

I'll do my best to stay on track here...

MAKE OF TRUCK
YEAR OF TRUCK
MODEL OF TRUCK
ENGINE SIZE OF TRUCK

I don't believe a vehicle alternator has a high enough voltage to constitute "bulk" charging.
If I had to charge off a TV I'd be tempted to get a 2KW inverter and wire it straight to the truck battery and use either the TT converter or separate smart battery charger.

At one point in time, quite a while ago, I talked to a guy who was running his TV and had plugged in his FW to charge it. I have not done that, but wondered if it would work since the truck does charge the battery as you are traveling down the road. Maybe that would work for you. If it would, you wouldn't have to worry about jumping from the truck battery to the FW battery.

Using the jumper cables is a great plan B but you will be violating RULE #1 as to NEVER MESS with your truck start battery system as this is your only way to get home.

A better solution is to install a SECOND DEEP CYCLE BATTERY to your truck battery system using one of these smart relays. This way you will always have a second battery available to use with the trucks stand-alone activities and not do harm to your truck alternator system. This second battery will only be normally charged whenever the truck battery is being charged and is switched away from your truck start battery when being used. This keeps from running down your truck start battery. This battery than can be switched into your RV Trailer needs or swapped out.

Read up on these two brands of SMART RELAYS



Your truck Alternator DC OUTPUT can range from 110AMPS to 250AMPs depending on what model alternator you are using... The 140AMP model is what most newer trucks are using today. The problem with using the standard alternator is when you connect in a second battery using jumper cables the alternator may only sense the close-by truck start battery and adjust its charging output current accordingly. There will be too much loss in the jumper cable due to the long lengths involved.

Also playing around with the truck start battery system will most likely end up really getting you stranded. Something I always want to steer clear of...

My 2KW Generator sitting secured in the tailgate corner of my covered truck bed is my main PLAN B backup source of power. I carry a portable VEC1093DBD 40AMP smart mode battery charger to charge my battery bank if needed.


usually somewhere on the campground is a 120VAC source in a localized bath room, rangers office, etc.. I always note where these places when going into my off-road camping sites. Never know when you may need to drive back and re-charge some batteries if need be. We are always running out of ice and fresh water on these trips too.

Roy Ken

Your truck may have a space for a 2nd battery, many do, under the hood. If it does place a battery there. When you drive to the store, etc. it'll charge.