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?

[Grit_dog]

pianotuna wrote:
Far better off to use 48 volts for storage.

Another Derp comment….how much do 12v LiFePO4 lose over time?
Yup, not enuff to matter. And ZERO with 1500w solar loading up the whole roof!

[CA_Traveler]

TurnThePage wrote:
The wide variety of responses has been so much better than I anticipated!

The longest wire run should be from the pvs to charge controller(s). I still don't know how I'm going to accomplish that part. I'm hoping to keep all other components within just a few feet of each other. I'm leaning toward sticking with 12v just for simplicity, but will still weigh my options as I acquire stuff.

I wired 3 panels in serial with the standard 10ga wire. 62' of wire 0.6% wiring loss. About 100Vmp, Consider a serial/parallel connection and be sure your controller can handle the panel Voc.

[Veebyes]

Sooner or later you will want to sell that RV. Who is going to want what you have done to it by changing the basic DC voltage system?

[Cptnvideo]

True, Don. But all DC components in a RV are 12 VDC to start with.

[pianotuna]

TurnThepage,

Look at battery power tools. No one uses 12 volts anymore.

[TurnThePage]

The wide variety of responses has been so much better than I anticipated!

The longest wire run should be from the pvs to charge controller(s). I still don't know how I'm going to accomplish that part. I'm hoping to keep all other components within just a few feet of each other. I'm leaning toward sticking with 12v just for simplicity, but will still weigh my options as I acquire stuff.

[Cptnvideo]

See our signature.
Ours is a 12 volt system. Simple. And no issues in a 50 amp RV with a residential fridge. One of my 3 A/Cs has soft start, but I have no issues starting the non soft start A/Cs.
Yes, higher voltage, smaller wire gauge. And for the roof solar to compartment controller, that is a big deal. But my controller, batteries and inverter are all next to one another so large wire is no big deal.

[Boon_Docker]

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

[pianotuna]

Far better off to use 48 volts for storage.

[CA_Traveler]

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.

[2oldman]

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?

[Grit_dog]

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?

[2oldman]

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."

[afidel]

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.

[Grit_dog]

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