DC to DC Battery Charging

[Riverman]

Can I install a 20 amp DC to DC charger in my travel trailer storage bay and connect it to my lithium batteries, while using the charging line that is in my Tundra trailer plug?

Any better ideas?

Thanks

[TaftCoach]

What are you trying to accomplish? There isn't much current coming through the trailer plug.

[Riverman]

Very simple.... charge two lithium batteries while traveling.

[boatguy]

Its likely that the 12v feed wire routed to your 7 way is not large enough gauge to handle a 20amp DC to DC charger. If you are lucky, it might be 12 or 14 gauge , maybe even 16 worse case, if its from the factory. Its used for "trickle" charging basically . A 20amp DC to DC charge wire will likely need to be at least 8-10 gauge depending on the length/run .

I installed a Victron 15amp 12/24 DC to DC charger in our converted van camper, and I ran 8 gauge wire to feed our Yeti 1000. Works great , but the larger gauge wire is needed for higher amperage "fast" charging .

Check and see what gauge wire is feeding your 12v charge port on your 7way .

[Riverman]

If it's less than a #10 wire I will just run a #6 as I have plenty. Thanks

[TaftCoach]

If you are simply moving from one point with hookups to a second place with hookups you'll be fine. There isn't much load.

[Riverman]

I don't use hookups... solar only when boondocking.

[billcf7]

Originally Posted by Riverman

I don't use hookups... solar only when boondocking.

Your best bet is to run a dedicated line from battery of TV to the DC-DC charger. A 10 gauge wire is good for approx. 80 feet at 20 amps

[01tundra]

Originally Posted by billcf7

Your best bet is to run a dedicated line from battery of TV to the DC-DC charger. A 10 gauge wire is good for approx. 80 feet at 20 amps

A 20A DC-DC charger will pull more on current on the primary side due to efficiency of the unit. I'd anticipate seeing a 25A+ draw on the primary side.

[Bullitt6283]

It depends on the wire size.


For example, the charge wire in the Roadmaster umbilical is 14 gauge, so 20 amps would be too much.
https://www.etrailer.com/Accessories.../RM-146-7.html
.

[DrSmart]

https://www.engineeringtoolbox.com/a...uge-d_730.html

[tomthumb]

They sell a 9 amp version. That will work with a 12 ga wire. Most modern trucks have a 12 ga cable for charging in the trailer loom. You won’t know until you check.

[Ann-Marie]

If you are trying to charge the lithium battery from the vehicle alternator all you need is a "lithium compatible Combiner 100". It is nearly 100% efficient and will isolate the lithium battery from the lead acid starting battery when the alternator is not running. It also draws no current when idle so it doesn't need an on-off switch like a converter does.

[TomC_AZ]

Do it direct like billcf7 mentioned. Using 6AWG is prob overkill. Just run direct from truck battery to the hitch area. Use anderson power pole plugs. This will allow you to use when you want not etc... Then on trailer route to how/where you need it. Simple and done. Is it totally needed, maybe, but if you always want 100% battery it is nice to have.

[440 scout]

Riverman, I recently installed a Renogy 40 amp dc to dc charger. The Renogy installation instructions will tell you the recommended wire size. The 40 amp unit requires 4awg size wire so I routed a 4awg welding cable from the truck's positive battery terminal to an anderson connector near the 7 pin but I also put in a 12 volt 60 amp inline circuit breaker-disconnect very close to the positive battery terminal. For the ground I used a short piece from the Anderson connector to a good chassis ground nearby. In addition, I enclosed the entire positive cable with split loom for added protection. Fyi, I got all parts from Amazon.