12v? 24v? 36...48v????

[TurnThePage]

I'm very near to picking up a new travel trailer that I intend to pack with solar and LiFePO4 batteries. It's a 30A 120VAC RV. I understand the electrical wiring advantages of the higher DC voltage configuration, but what does everybody do with their 12v appliances?

I'm hoping for around 1500 watts of solar and no less than 1000Ah of 12v batteries. Is there a good reason not to stick to a 12v configuration?

[2oldman]

ewarnerusa wrote:
Or from another angle, a higher DC inverter won't be as negatively impacted by the voltage sag when you really draw down hard to meet a big AC load like microwave or even go for the air conditioner.

This is correct. Acid batteries and huge 12v draws don't always work so well. Not only is 4/0 cable difficult to work with, batteries and connectors will start to heat up drawing hundreds of amps over more than a few minutes.

In my opinion, 12v is not the best idea IF you regularly power large appliances with an inverter. For most RVers, I don't think this is a big issue, and 12v is just fine.

[ewarnerusa]

I've heard that a higher DC baseline can help reduce the impact of voltage sag. This can allow for skinnier wires, as mentioned. Or from another angle, a higher DC inverter won't be as negatively impacted by the voltage sag when you really draw down hard to meet a big AC load like microwave or even go for the air conditioner. But if you're not devising a way to run big loads off the battery, I can't see why you would want to add the complication since your entire camper DC system is setup for 12V.

[StirCrazy]

TurnThePage wrote:
I'm very near to picking up a new travel trailer that I intend to pack with solar and LiFePO4 batteries. It's a 30A 120VAC RV. I understand the electrical wiring advantages of the higher DC voltage configuration, but what does everybody do with their 12v appliances?

I'm hoping for around 1500 watts of solar and no less than 1000Ah of 12v batteries. Is there a good reason not to stick to a 12v configuration?

you have to keep the 12V apliances but use a step down converter to run them like some one mentioned already.

my question is what do you think your going to gain by running a 48V storage setup over 12V setup? you said your not worried about inefficiencys but is the very slight increase in efficiency you gain with the lower amprage levels nd higher voltage levels between your battery and the stepdown converter worth it? on the AC side its the same thing but you can offset that by proper sized wires between your batteries and inverter.

with the money you save not buying a 48v to 12V inverter converter you could buy a 270ah battle born battery.

if I was going to do your system I would get four of the 270AH dragonfly/battle born batteries which ever you can get cheeper (who am I kidding if it was me I would just build my own but thats not the pourpose of this post) then I would get a good inverter to meet the needs of what you need to run and mount it right beside the batteries. for solar panels that is where I step the voltage up and run 24V panels in series as thats the longest wires in the setups.

in a home solar storage off grid set up I can see spending the money on a 48v set up as you are running a lot higher of an inverter output and the wires from the battery bank to the inverter would just be stupid, but 9 time out of 10 your never going to need larger than a 3000watt inverter in a rv using 2/0 cable you can handle 300amps at a distance of 10 feet, so there is some safety built into that as you should cut the distance down in half and a 3000watt inverter will draw about 250amps when running full out (plus a little for inefficiency.) on the other side a home system may be running dual 5000 watt inverters (or more) to provide 220V power and run the whole home so on that scale and size the cost difference in wire and the amount of amps involved makes it benificial.

I just don't see it in a rv set up, but thats my thought, if you have a different path of reasoning I would love to hear it as maybe I am missing somthing.

[time2roll]

I have 675w solar, 1000 AH battery and 2000w inverter all at 12 volts. Works great. Large battery is not a big deal but a larger inverter and solar starts to be impractical. With 1500 watts solar may need 2 or more controllers at 12 volt. Inverter maybe 3000w would be 12v maximum and even that would be better at 24v.

Equipment at 36v is fairly thin. I would avoid this. Equipment at 48v is probably overkill unless powering a 50 amp RV with two A/C and probably 2kW+ solar.

Charging from the vehicle needs a step up converter, powering existing 12v items needs a step down converter. Step up for charging may not matter much with 1500w solar. Step down need enough power to run the slide, emergency braking, and leveling system if equipped. Some of these 12v items can be high amp draws and exceed the rating of most equipment.

Post a list of primary equipment for evaluation before purchasing.

[2oldman]

wa8yxm wrote:
so your most efficiecent install will be 12 volt all the way..

I have 835w of solar so I don't care about efficient. Conversion losses are tiny compared to my usage.

[WNYBob]

Here's a site with good information.
Samlex America (no affiliation)

[wa8yxm]

in high power installs (Say house 120 volt back up) higher voltages = smaller wires but in an RV the wires are not that long... There may be other issues too but I'd stick with 12 volt cause that's what you eat.

Arguing against other configurations: IN order to feed your 12 volt stuff including Control power for Fridge, Water heater and AC as well as lights (You can buy other voltages) fans (Theroatically you can get other voltages) and the Furnace (12 volt) and water pump (12 volt) you will need to "Convert" the higher voltage down.. There are several "Conversion" methods which range from wasteful to WASTEFUL!!!! of energy... None are 100%.. so your most effieicent install will be 12 volt all the way.. Well. 13.6-14.2 but but we still call it 12.

[TurnThePage]

rk911 wrote:
i'm an old fart and have always tried to live by...keep it simple, stupid. the more wonky a system, the more headaches it will cause.

I absolutely agree!

2oldman wrote:
Victron 48 >12v converter. I got the 30a size to handle slides and jacks

THAT'S the info I was looking for! Thanks! I figured stuff like that was available, but was in danger of drowning in data when perusing their website.

[rk911]

i'm an old fart and have always tried to live by...keep it simple, stupid. the more wonky a system, the more headaches it will cause.

[2oldman]

Victron 48 >12v converter. I got the 30a size to handle slides and jacks

[TurnThePage]

None. The trailer comes with a 12v compressor fridge, and the usual other stuff, like 12v water pump, 12v controls for the furnace, etc.

And that's my point. Why go with the more efficient, yet non-conforming higher voltage systems? I only ask because my learning process includes videos of people that have made beautiful systems, come back and say if they could do it over, they'd opt for 24v or 48v.

I could see it in a bigger rig maybe, but that's why I'm asking. I'm not the sharpest knife in the drawer and don't want to make an expensive mistake.

[rk911]

what DC appliances that use other than 12-volts are you looking at?