Wiring a DC_DC Charger

Hi,

Would it be possible to have the output wire (with a SAE plug) from the DC-DC charger pluged into the external solar plug which is wired directly to the batteries? I have moved my Li batteries inside my small RV and looking to avoid drilling a hole in the floor to get the DC-DC output cable inside. The DC/DC charger would be located in a front tub where the external plug is also located. The wire size for the plug is 10 AWG and has a 30 amp fuse in line. This would be for a 20 amp or less charger. It would look like something like this.

Thank you

I would install the fuse holders as close to each source as possible (<3”) and before the plug. Use the SAE plug with the 10ga wires.

RV10flyer said:

I would install the fuse holders as close to each source as possible (<3”) and before the plug. Use the SAE plug with the 10ga wires.

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tks..The fuse holder shown between the SAE plug and the bus bar is actually right at the plug.

Would a fuse be required between the SAE plug and the charger? Is that what you are saying?

Chaucer said:

tks..The fuse holder shown between the SAE plug and the bus bar is actually right at the plug.

Would a fuse be required between the SAE plug and the charger? Is that what you are saying?

Click to expand...

I put one on both ends of the circuit on my Victron. Victron says they are internally fused but it’s non replaceable. So I went with the smallest fuse possible. Mine has 15A output, so I used 20A with 10ga wiring.

I am going to be installing this same unit in my Land Cruiser and I am wondering what gauge wire to use. I am planning on mounting the charger in the rear of my vehicle and I think the run from the starter battery to the charger will be about 10-15 ft. I’ve been looking at different wire size calculators but don’t know what voltage drop is for acceptable. Will 8 gauge wire be ok for this length of run and a 20 amp charger?

A 20A load over 30 feet (out and back) on 8AWG copper wire will have a voltage drop of ~0.37V which is just over 3% of a 12V system.
Many folks use <3% as a target for "critical loads" (B2B charger counts because .37V can make a difference in sensing when to turn on) 3-10% for non critical (lights) and >10% should be avoided (wastes energy).

A decent calculator is here and they show % drop of just over 3% for 8AWG and ~2% for 6AWG. If the run is closer to 20 ft round trip then 8AWG may be in the "<3%" range.