24v , 48v - pulling 12v some loads

[KD0CAC John]

A lot of what is available these days seems to be 24v , 48v systems - batteries etc.
I am looking to redo an RV system - most loads are 12vdc & 120vac .
Most of the better components / systems seem to be 24v-48v - and inverters set to either of these voltages .
I like the idea of higher voltage for typical reasons - but still especially with RVs , 12vdc .
What I have found look to be best gear for price - EG4 inverters and rack battery Lithium EG4 .
So the question is - most efficient way to supply 12v loads ?
A 2nd preference low RF noise - using for ham radio ? 

[f4eru]

best option is to exchange the heater resistors for big resistive heater loads, and to get a buck converter for all the small loads.
Not sure if the conversion is worth it...
Check your LED lights if they could support 24V out of the box.

[KD0CAC John]

Do not use heater resistors .
Lighting , furnace / propane / fan 12v , water pump , fridge / propane 12vdc & 120vac .
Then inverter for AC cooling .
I also have 2 Honda EU2200i - that are setup for parallel - 4400 watts surge .
Most of my solar panels are 24v .
My last system was 12v with inverter & lead batteries , Ran all loads , including air conditioning and never went below 50% discharge . 

[Simon]

generally when stepping up the bigger the step the worse the efficiency as the currents drawn at the lower voltage are large. So starting with 48V is always better than 12V as it means that 1/4 the current is required for the same power.

You should be able to get a step down converter for the 12V stuff, you could run a separate 12V battery system? I'm not sure why you worry about RFI on your 12V conversion, I'd be more worried about the garbage you inverter is causing unless you have a really good inverter that is not one of the cheap ones.

[KD0CAC John]

Well the battery / inverter I mentioned are some of the best for the price currently available , as far as I know , I have been around & building systems since the late 70s / 80s .
Then , again this is for RV service - so adding another battery / voltage , without 12v charging is an issue [ unlike in a building where the space is generally more available ] .
RFI - maybe you do not know what ham radio is --- RFI is a big deal - some of the junk electrical stuff CAN totally eliminate ham radio - another reason for 12vdc .

[Simon]

well crap converters that have not been tested. Surely a commercial converter that is CE or equivalent marked has been tested as part of the approval and should not be for sale if it fails test.