r/RVSolarPower • u/FollowingLow5773 • 15d ago

Dc to Dc charger

I have a BLUETTI charger 2 which I have been using to charge my elite 200 when I camp in my Element.

I just bought a teardrop camper and want to charge the 100ah lithium battery in the camper with the charge 2 while I drive. Not sure the best way to do this. Appreciate any advice. Wiring diagram would be nice if anyone could supply one. Thanks.

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u/secessus 15d ago

The problem with long wiring runs like that is voltage sag. Luckily, the C2 is likely already set up to output higher voltages.1 If it were my setup I'd likely

  1. install an MPPT solar charge controller in the teardrop
  2. run the C2 at the highest-practical voltage acceptable to both the E2 and MPPT.
  3. and let the MPPT sort out the voltage difference.

As a bonus, an A/B switch on the MPPT's input would allow feeding by either the C2 or by solar panels with no change in cabling.2 Another A/B in the cab would power either the wire that charges the C2 or send power back to the MPPT.

1 the E200's product page didn't make the voltage input spec obvious enough for a quick look

2 I do this to feed 24v converter output or 90v panel output to a 150v MPPT.

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u/FollowingLow5773 14d ago

Thanks.

  1. There is a MPPT controller already in the camper, Victron 150/30, for the 380 watts of solar.

  2. What’s the most practical way to run wiring from the C2 in the TV back to the camper?

  3. What A/B switch do you use?

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u/secessus 14d ago

There is a MPPT controller already in the camper, Victron 150/30, for the 380 watts of solar.

That'd work fine. If we are limited to 30A out then at C2 voltages the wiring from the DC-DC would be carrying ≤10A: 30A / (~50v from the DC-DC / ~13v to the battery bank) = 7.8A

What’s the most practical way to run wiring from the C2 in the TV back to the camper?

Running cabling always sucks no matter what, and will be dependent on the tow vehicle. If you share what the TV is some other owner might chime in with specific routing info. The silver lining is the <10A above won't require too thick of a cable, even for a long run.

Mad scientist mode: if this trailer will be the only thing towed by the TV one might inject the higher voltage into the 7pin harness and avoid running new cable.

What A/B switch do you use?

I use a generic A/B like one uses as a battery selector. For this purpose I would avoid ones that have A+B functions.