12/48V converter vs battery/charger for 48V RV conversion?

[fastline]

I am looking to convert an RV to a 48V pack. I will still need to step back down to 12V for DC loads in RV. My options are a DC/DC converter or battery with 12V charger. I am weighing those option. Anyone have experience with either? I have been looking at options but one that might force the battery option is if I install an onboard generator that will have 12V starting. That will probably pull 1000w or more. Seems most of the DC/DC converters I am finding won't adjust up to a reasonable float voltage for a battery but probably not a good idea anyway.

I recall seeing where one guy did a battery with 30A charger but was not able to hold all the continuous 12V loads.

I am also curious about idle power or efficiency of the DC converters vs charger setups?

 

[chrisski]

I thought of an 48 volt upgrade, and lack of a converter to power leveling jacks is one reason I went for 24 volts and got rid of the 12 volt battery, using converter only.

I needed 50amps for leveling, and purchased a 70 amp converter. I got the Victron Orion 24 volt to 12 volt 70 amp converter. These can be placed three in parallel for more amps, but I don’t know if that would start a generator. Generators 100 amp BMS, but should start with a 200 amp BMS. Maybe two or three in parallel would work.

Problem with higher amperage needs, you need to buy them to see if it works. Gets expensive. Specs just don’t see, to be written. I found no specs that met my 50 amp 12 volt need from a 48 volt battery. Starting a generator is more than 50 amps.

 

[houlster]

I have a 24v bank, but left the OEM 12v batteries in place along with an Orion 24/12 converter. If I'm on shore power, I leave the original 12v converter in the RV turned on. If I'm un-hooked, I flip the breaker for the converter off and the 24/12 converter keeps the 12v system charged. No worries about heavy 12v loads over-loading my converter this way.

If you can get a 48/12 converter, even a smallish one will work if you keep a 12v battery in the system. Heck, could even just leave the original RV converter in place to keep it charged, but without shore power, you have the extra conversion losses going from 48v DC -> 110v AC -> 12v DC, plus whatever it draws would take away from your inverter capacity.

 

[kbeefy]

If/when you add a generator, just give it it's own 12v battery. It can be a tiny lawnmower battery, however much the generator requiers to start. I think some even have the battery on board. As long as you leave it as a dedicated starting battery the generator will charge it, no need to tie into the rest of the 12v (or 48v) system.