Velit 12v AC?

[ReluctantTraveler]

Ok, I'm utterly turned upside-down by the 12v vs. 110v AC debate.

All of the math I've done indicates that a 12v unit can run much longer, drawing 670 watts or so on the high end of the spectrum (55 amps x 12 volts), compared to 1440 watts for a 110v unit (12 amps x 120 volts).

But I've also been seeing some reports that a lot of 8-12k BTU 12v units have trouble keeping up when it's particularly warm and humid out.

As someone who's not particularly well versed in HVAC systems, can anyone help me make sense of this?

 

[ReluctantTraveler]

I think I've got it figured out. It's the difference in BTUs.

For example, the Nomadic X2 has a similar 8k BTU/55 amp draw rating as some of the others we've looked at. The Nomadic X3 is a 12k BTU unit, and it draws 110 amps at max power, or... 1320 watts, basically the same wattage as the 110v Coleman Mach 3.

@Ozarker this explains why you were saying the 12v units are no more efficient than 110v. If you're comparing BTUs to BTUs, you're spot on, but many of the 12v units look more efficient on paper by having a lower overall cooling capability.

Which means I'm now looking at inverters to see what I can do with my current system. I don't want to expand the battery bank, but if I could get an hour or two of AC out of the my bank while we live the dog behind for a bit or eat lunch on a 90 degree day, that would be great! I'd pair that with a dual fuel source inverter generator for boondocking.

 

[Ozarker]

Gotcha. So... I have an existing trailer with an existing 14x14 hole the roof with an existing 110 ac unit already in it.

I'm certainly not going to cut a new hole in my camper for a window unit.

This is also one of the "turn the knob warmer or cooler" 12k BTU units that is, frankly, wildly over-sized for our 100 sq. foot travel trailer.

We are mostly on shore power, except for when we're not. And doing math on the numbers supplied directly by Coleman, running off an inverter would get us a max of 1.75 hours before our LiFePo4 battery is fully discharged, versus 6 for the 12v.

Make it make sense.

I think you meant to say 12v is not as efficient as 110v.....

if you need to replace a unit do so with similar or the same kind of unit that was OEM.

Now, toss in a genset and you got it made.




if you want a unit for your dream camper unit, try looking at what has been said.

 

[ReluctantTraveler]

I think you meant to say 12v is not as efficient as 110v.....

if you need to replace a unit do so with similar or the same kind of unit that was OEM.

Now, toss in a genset and you got it made.




if you want a unit for your dream camper unit, try looking at what has been said.

I really wish you had read my question (or my multiple comments reiterating I was talking about my existing trailer) before all of this back-and-forth.

 

[andy_b]

To clarify your question - you're hoping to replace your current 110v AC to that specific 12v DC model because it fits into the existing hole and to minimize theoretical inverter losses while running AC on battery alone to keep your dog safe?

Based on how you describe your travel (regular access to shore power, minimal time battery only time while using AC), wouldn't it be cheaper to just add a few more batteries? Since you have regular shore power, no need for more solar and the associated wiring. Since it seems as though this trailer will eventually be replaced, adding batteries could: 1) add resale value, 2) provide a great DIY learning opportunity, 3) minimize downtime.

A reliable LiFePo battery like an SOK is great. Or, you could roll the discount dice and get something slightly less reputable on Amazon or similar.

 

[ReluctantTraveler]

To clarify your question - you're hoping to replace your current 110v AC to that specific 12v DC model because it fits into the existing hole and to minimize theoretical inverter losses while running AC on battery alone to keep your dog safe?

Based on how you describe your travel (regular access to shore power, minimal time battery only time while using AC), wouldn't it be cheaper to just add a few more batteries? Since you have regular shore power, no need for more solar and the associated wiring. Since it seems as though this trailer will eventually be replaced, adding batteries could: 1) add resale value, 2) provide a great DIY learning opportunity, 3) minimize downtime.

A reliable LiFePo battery like an SOK is great. Or, you could roll the discount dice and get something slightly less reputable on Amazon or similar.

Yea, so, I eventually realized that the reason why I was hung up on the math was a BTUs difference. All of these 12v systems are 8k BTUs, which is why they draw fewer amps. The one true 12k BTU system has the same draw as the 110v system.

Took a lot longer than it should have for the dots to connect for me.

I already have 270ah of BattleBorn LiFePo4 (one of their GC3s). Just picked up an inverter. That should get me 2ish hours of AC, which is good for lunch or a quick stop somewhere with the dog in the trailer. I also picked up a dual fuel generator to use if we need more time than that or end up overnighting somewhere and need AC.

It was cheaper than the 12v AC, and will probably work better.