where does the TV battery charge wire go?

Tundra57

I have a 2019 tab 400 BDL. I am fitting a battery charge controller to the tab so that my TV can reliably charge the Tab battery while driving. Does anyone know where the wire from the trailer plug junction box is run to the tab battery? I need to break into this wire to fit the charge controller.

I have asked Nucamp via their website, on two occasions for wiring and piping diagrams, but to date they have not even acknowledged my EMails requesting help.

rh5555

I don't know if the 2019 400 is the same as the 2020 400, but my charge line from the TV connects to the circuit board that contains your low-voltage fuses here:

The thicker lead to the right goes to your trailer's battery.

nhmike

I’d double check (or triple check) with NuCamp..  Customer service is typically very good.  Maybe your mail isn’t reaching them.

ScottG

I believe the 400 features a similar junction box for electrical distribution as the 320. In that case, the pigtail 12V, positive feed to the converter, positive battery terminal, and power to the breakaway brakes are all tied together at a single terminal stud.

You can find a few diagrams and images here.

rh5555

Interesting, I haven't found that box on the 400, but it makes sense.  Maybe the wire I identified above comes from here.

ScottG

In the link I provided above there is a diagram provided by nuCamp of the wiring in the 400. It's not a particularly good or thorough diagram, but it does show a junction box as part of the system. On the 320 the junction box is centered on the frame near the front. Maybe a 400 owner can point us to its exact location on that model.

Denny16

Follow the trailer to tow vehicle 7-pin cable, it will take you to the junction box, which is centered on the front frame cross member, under the front gas tub, behind the spare tire rig.
cheers

ScottG

Thanks, @Denny16. Sounds like the same location as the 320.

Tundra57

I did finally get a reply from NuCamp. According to them on my 2019 model both the tab battery and 12v from the shore power to 12v converter tie together at the trailer plug juction box as @ScottG shows. So I would have break into the Tv 12 v charging input before that connector, so in my case the TV charge controller would probably be easiest to mount in the propane box at the front. Thanks @rh5555 , @Denny16 and @nhmike. I'll report back if it solves the problem.

ScottG

On a related note, I'm curious as to what you are installing and how it will work to improve the charge capabilities of your tow vehicle. Does it do something to optimize the voltage/current from your alternator?

N7SHG_Ham

@ScottG, the device is probably a DC-DC converter, it steps up the input DC voltage and outputs the proper charging DC voltage compensating for line loss getting to battery.

Installed close to the battery you give the battery the proper charge voltage. One such product:

https://www.etrailer.com/Battery-Chargers/Redarc/331-BCDC1240D.html

Cbusguy

I have the renogy 20 amp version  to charge my lithium to the proper voltage while towing,   You definitely must upgrade beyond stock wiring and the stock trailer connector.   I ran 4 gauge from the alternator back and a 100 amp anderson connector for the TV to trailer connection then 4 gauge to the charger continuing through to the battery.    

The charges said I could have gotten by with 8 gauge,  I intend on only running this one.

Tundra57

@ScottG yes it is a charger designed for sealed lead acid batteries and includes a boost DC to DC converter which will draw extra current from the TV to provide the correct voltage to charge the tab battery. This does mean, for example, that if the tv is only providing 12v, to provide a 20Amp charge at 14.4volts the converter will draw 24Amps from the TV so as @Cbusguy says it will be best to increase the wire size from the TV battery to the trailer plug if it is less than 30Amp. Right now without  my Tundra senses its own battery current and when it's battery is charged it reduces the voltage from the alternator so it's own battery can't boil. This also has the effect that the voltage to the trailer plug is reduced, this voltage will drive very little current into the Tab battery, as this is driven by the difference in voltage between the TV and Tab batteries.

So I expect the added Charger will solve this problem.