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

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.

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.

Stick with 12V. Series/parallel however many batteries you add and leave it at that, IMO.
This is a solution looking for a problem that doesn’t exist.
JMO

Personally I'd run the 12V stepdown converter into a 12V battery, either lithium or SLA. That way peak loads for the slide motors and compressor motor get taken up by the 12V battery and the 12V converter can just top that off. I know there are folks that team a couple of 12V stepdowns together to supply the loads, but it has to be much more stressful on the components in them than if there was a decent pool of ampacity there. Since you aren't actually using it for storage capacity a 50Ah 100A LiFePO4 would work great and they're like $160.

The big advantage of 48V is you can use a much cheaper MPPT controller since they're basically priced on output amps and 48V is 4x lower amps for the same watts. Wiring costs are also much lower since you get to drop down to wire gauges which are commonly available instead of double 0 or triple 0 cables.

afidel wrote:
The big advantage of 48V is you can use a much cheaper MPPT controller since they're basically priced on output amps and 48V is 4x lower amps for the same watts.

Yep, another advantage. My motto is "Wire handles voltage a lot easier than amperage."

Lol, you guys are 2funny!
How much DC current u think this feller gonna pull in a little camper.
He’s not building a data center, he’s stocking up on battery reserve for off grid camping (or he wouldn’t need all the batteries he’s planning on installing…).
This is becoming laughable. Talking 2/0 and 4/0 cables. Lol. U think he’s using the batteries to start his diesel truck 20 ft away or what?

Grit dog wrote:
This is becoming laughable. Talking 2/0 and 4/0 cables. Lol. U think he’s using the batteries to start his diesel truck 20 ft away or what?

I don't know why you're hurling insults. He's loading up on a lot of power. Have you never read the manuals for large inverters and see what cables they recommend?

1500W is 125A @12V hence equipment layout is also a consideration as to much wiring voltage loss is a consideration. And the solar controller, inverter, charger and battery proximity is a factor.

All of the equipment, your intended usage and expectations and cost are also factors. Look at the entire system and various tradeoffs for what is best for you as there are many considerations besides DC voltage.

Far better off to use 48 volts for storage.

2oldman wrote:

Grit dog wrote:
This is becoming laughable. Talking 2/0 and 4/0 cables. Lol. U think he’s using the batteries to start his diesel truck 20 ft away or what?

I don't know why you're hurling insults. He's loading up on a lot of power. Have you never read the manuals for large inverters and see what cables they recommend?

Typical response. :R