Community Forums

Tinfish · 02-03-2020, 01:57 PM

What system do recommend so that the batteries on my trailer will charge while I’m plugged into my truck while towing it.

J Birder · 02-03-2020, 02:15 PM

It is likely that all of the required wiring is already in place. It is also likely that there is a fuse in the truck that was not installed. The factory leaves that fuse out in order to avoid having a hot unterminated wire.

Joel

mokurt · 02-03-2020, 02:39 PM

Yes there should be a hot wire in the plug receiver on the truck.

Oregon RR · 02-03-2020, 06:20 PM

Looks like the OP got his answer. Been thinking about the TV feed into the trailer.

Does the voltage regulator on the truck "see" the trailer batteries or is charging voltage only based on the TV's battery(s)??

For example, if the TV battery(s) were discharged deeply and the trailer was fully charged, would the truck continue to push 14.4 volts plus into the trailer batteries? Would a potential overcharge exist? Boil the Trailer batteries on a hot day?

twinboat · 02-03-2020, 09:18 PM

The voltage of the TV battery will drop, once you connect the lower voltage, trailer battery to it. Voltage flows from high to low.

If you ever jump started a car with a running car, you can hear the alternator of the running car whine a bit as it ramps up its output.

How much the TV battery volts drops, and how many amps move thru it, depends on the wire size, lenght and alternator amp capabilities.

The alternator will sense the TV battery voltage drop and increase its output.

All alternators are regulated for 12 volt batteries, they will not overcharge them.

Tinfish · 02-04-2020, 04:05 AM

Thank you for your replies. I’m going to check the fuses and truck info. It’s a 2019 Ram 1500. Thanks again

Persistent · 02-04-2020, 05:18 PM

Some tow vehicles are different from others regarding charging ability. Usually they are designed to efficiently charge the engine start batteries.

In general, a truck tow vehicle will not likely overcharge the TT house batteries. The line loss and connector loss will limit the charging of house batteries. 10 gage wire from the truck alternator to the 7 pin hitch connector and ground tend to limit charging. Larger cabling can do better.

I would measure it to see what it is doing. Measure the voltage at the house battery terminals. Or better yet measure the current flow. Test when house batteries are low and again when they are fully charged.

Cat · 02-04-2020, 05:35 PM

FYI 2015 up Ford F150 not sure about other models, have a very small power wire running back to the trailer plug, 18ga wire if I remember correctly. So you are not going to get much back to the trailer with a 11 foot long 18 GA wire. I like others ran a wire 10ga from my truck battery back to a new truck side 7pin connector.. Also the truck with the Ford wiring will not supply any power out unless you start the engine put the truck in gear. After that, it stays powered until you shut off the engine.

astrocamper · 02-10-2020, 09:24 PM

Roof top solar works both in camp and while driving down the road.

billyw · 02-21-2020, 10:37 AM

Quote:

Originally Posted by astrocamper

Roof top solar works both in camp and while driving down the road.

That's my solution too. In the 15 years my panels have been on the trailer roof, I haven't had to worry about charging the batteries, except in extended cloudy/snowy winter time.

keymastr · 02-21-2020, 10:56 AM

Be aware that the Ram trucks may discharge the truck battery if you leave the trailer connected overnight. Ford will not, don't remember if GM does. You should add an isolator if you put the charge relay in or eventually you will be needing a jump start, usually when it is least available.

Danattherock · 02-23-2020, 07:43 PM

Quote:

Originally Posted by keymastr

Be aware that the Ram trucks may discharge the truck battery if you leave the trailer connected overnight. Ford will not, don't remember if GM does. You should add an isolator if you put the charge relay in or eventually you will be needing a jump start, usually when it is least available.

How do i determine if my TV battery can be drained if TT is connected overnight?

2017 toyota tundra trd pro. First TT arriving this week.

Thanks

twinboat · 02-23-2020, 08:05 PM

Get a test light or volt meter and test for voltage on one of the trailer plugs pins of the TV, with the key on.
As long as the lights are off and no one is stepping on the braked, the hot one is the trailer feed charge line.

Now turn off the key and see if the power goes away. If it does, its a switched circuit.

ttavasc · 02-23-2020, 08:55 PM

Quote:

Originally Posted by Danattherock

How do i determine if my TV battery can be drained if TT is connected overnight?

2017 toyota tundra trd pro. First TT arriving this week.

Thanks

See the attached image below for the pin out on the 7 way connector. Use your voltmeter with positive to pin 4 and ground to pin 1 on the Truck connector per twinboat's procedure.