Renology 20 amp DC to DC charger

[Bill M.]

My truck does not charge the batteries much when driving. I am thinking of adding the unit in the title. Is anybody using one of these? Is it likely that the existing wiring in the truck (2007 Dodge diesel) is heavy enough to run this unit through the 7 pin? does anybody have a different recommendation?
thanks
Bill

PS.. I am also thinking about going to lithium batteries. Should I look at a different unit than the above? They make a 60 amp and I could add wiring to the truck, I guess, but would hate to.

[rickst29]

Your limiting factor is the very thin "trailer battery charge" wire inside the Bargman Cable. If you bought the 60A version, you would overheat this wire and burn the insulation. The burn would possibly also extend to include others wires and the main sheathing as a whole, destroying the cable. That is probably also be true of the 40A version.

The Renogy supports multiple types of batteries (SLA, AGM, LiFePO4), and you can separate your "battery upgrade" project from your "charge from the TV" project. I did a home-built "charge from the TV" upgrade several years before I replaced my SLA batteries with LiFePO4, and I recommend that you do your Renogy project first. The Lithium Upgrade (new converter, bigger wires inside the Trailer, Coulomb-Counter Monitor, and maybe an inverter) is a bigger job.

My "home-built" is much more complicated, and roughly equivalent to the Renogy 40A. But it solves the Bargman cable issue by boosting TV Voltage (only on the the "Trailer Battery Charge" circuit), from ~13V to exactly 36V, and then uses an MPPT Solar Controller to drop the Voltage back down for batteries. It took about 3 hours of work in each vehicle (my 4Runner TV, and my Trailer.) You can look at my previous posts, if you're interested in duplicating that method. A Solar system with MPPT is pre-requisite.

[jeffmc306]

Originally Posted by Bill M.

My truck does not charge the batteries much when driving. I am thinking of adding the unit in the title. Is anybody using one of these? Is it likely that the existing wiring in the truck (2007 Dodge diesel) is heavy enough to run this unit through the 7 pin? does anybody have a different recommendation?
thanks
Bill

PS.. I am also thinking about going to lithium batteries. Should I look at a different unit than the above? They make a 60 amp and I could add wiring to the truck, I guess, but would hate to.

Hi Bill, great question! If you haven't seen it yet, check out the installation GMFL just did Long, Long Honeymoon

Here's the part of the YouTube video of it where he explains the installation of the Renogy DC-DC unit and how it works.

If you're thinking of going bigger, check out the Ausie company Redarc. These guys build some larger units that also include solar charge controllers that will automatically select which power source to charge your batteries (any kind).

With any of the units, you'll run a pair of large gauge (6 gauge or larger) from your truck's battery with a fuse under the hood, back to the bumper. They use an Anderson-style connector (like a fork lift battery connector) and another on your trailer connected to the DC-DC unit.

See Post#102 from the LoLo install for photos that Ronnie provided of the DC-DC wiring.

It's a great way to ensure your trailer batteries are charged while driving.

Good luck!

[jeffmc306]

I just received an email from eTrailer on this topic.

Here's a link to their article

HOW TO CHARGE A TRAILER BATTERY WHILE DRIVING: 3 COMMON PROBLEMS (AND HOW TO FIX THEM)