[Guide] Renogy IP67 50A DC-DC Charger + MPPT (for leisure battery) -- How We Done It --

[TallPaul_S]

Ground to SB, LB, and PV. All normal, just that you'd only normally have ground to SB in an isolated DC-DC charger. Just have the SB ground going to your chassis ground, and your shunt (if you have one) also connected to chassis ground.

 

[roooms]

Thanks for the explanation @TallPaul_S . But what do I do with the other GND cables coming out of the unit then?

 

[TallPaul_S]

That's the 3 black grounds. So the other 2 - one will go your negative leisure battery terminal (directly or indirectly via a shunt), the other is the negative for the solar panel.

 

[roooms]

Ah ok. I think some online wiring diagrams where everything seems to meet at busbars is confusing me. So if I do eventually connect to PV then I need to run a negative (and pos) all the way from the renogy to the PV and can’t terminate at local chassis grounds, like you would something like LED lights? (I need to learn more)

So why does the 50A being reviewed at the start of this thread have only a single GND then?

 

[Dellmassive]

Thanks for the write-up on the Renogy 50A @Dellmassive, I thought the same about it being a Redarc copy when my 40A DCDC + MPPT arrived today. It's a Renogy RBC40D1S.

I'm a bit concerned that this model has three (black) GND wires fixed to the unit, which seems unnecessary if you're grounding to the chassis, rather than a negative back to the starter battery, leisure battery and solar. Any idea why this has been done this way? Should I connect all to a negative bus bar? Or just one? It's a bit strange combined with my limited understanding.

Interestingly this unit prioritizes SB over solar, which I think is an improvement over previous units that would switch to solar even if that meant slower charging than SB.

View attachment 266777View attachment 266778View attachment 266776
View attachment 266779

I've not tested that exact unit.

but id imagin they do that for the american market where the motorhomes are all wood and fiberglass,

so they give you a wire to connect to for each of the grounds, PV, SB, LB.

id imagine they are all connected together internaly.

i would just ground them all out to the same chassis neg on the van, either all to the same ground stud or use a NEG bus bar.

looks like a nice unit though.

good to see Renogy contuing to inovate and keep churning out new and improved proctucts.


.

 

[roooms]

Ah, that makes sense assuming you then need to run cable everywhere. I'm glad I don't have to do that though.

So, with that in mind, am I mad to think you'd only really need to ground one, and the others could be heat shrink covered or taped off?

Thanks again for the write-up on the similar unit. This helped me. And thanks again to @TallPaul_S for the help yesterday.

 

[rod_vw]

I will poke my nose in here being willing to be shot down!

Personally I would connect all three together and continue them to -ve bus-bar or chassis ground with a large enough cable to ensure no significant volt drop under the maximum possible current flow plus a small margin.

Rod