features for dc to DC chargers

theoldwizard1 wrote:

time2roll wrote:
Primary feature is amp rating. JMHO. Bigger is not always better and watch the input amps. The rating is output.

For any kind of trailer, you need to remember that the input limiting factor is the fuse on the battery wire in the 7 way connector.

Watch the video I linked before ! The first thing that happened when he started his test was that he blew the fuse !!

Which is a pretty good indication that trying to run a 40 amp DC charger through the trailer charging circuit isn’t going to work. When I was in my pre-purchase learning phase, I remember reading on one of the DC-DC charger manufacturer sites that the majority of the “This @#$& thing doesn’t work!” complaints they get are due to the installer not following the wire size recommendations in the instructions.

There were several things I didn’t like about the video, and the way he was demonstrating the charger. He initially suggested that the unit could be connected directly to the alternator (nope!) or the starting battery, he then reinforced that misinformation by referring to the starting battery in the RV (that you could clearly see he was connecting to) as the alternator, and finally hooking it up in such a half-a$$ed manner that the input fuse blew just left me shaking my head.

The smallest gauge wire recommended for the Renogy 40 amp charger he was demoing is 6 AWG, regardless of how short the circuit length is. What he was using wasn’t 6.

Just for grins, I read through the instructions for a Renogy 40 amp unit just to see what they said for an installation like mine. The circuit length between the starting battery and the Redarc charger is about 27-28 ft long, and Redarc recommended 4 AWG wire and a 60 amp fuse. Renogy also recommends 4 or 2 gauge wire and a 60 amp fuse on the input side.

:):)