A/C on solar

[Edpritt]

So I would like to run my air conditioner without running my generator. I am looking at the marine air 11,000 BTU self-contained unit.

https://www.marinaire.com/Marine-air-conditioner-11000-btu-110V-p/msba11k2.htm

I have 800 amp hours of 12 V lithium batteries. I have a 3000 W pure sine inverter. The technical specs for the air conditioner are:

Max. input consumption 1250w
Running Current 7.9amps
Strating Current 14amps

Will this work?

Thanks for the support.

 

[FF]

Max. input consumption 1250w
Running Current 7.9amps
Strating Current 14amps

Will this work?

Sure ,just not for long.

Your running current is 7.9 amps of 120V AC.

This will require 80amps of 12v DC as a bare minimum.Probably 100A tho.

800 amps of batts might be good for a couple of hours at best, because when discharging at a high rate the batts die sooner.

Replacing 800Amps will require a huge solar setup , as other loads will also be being fed like the reefer.

 

[DavidM]

We debate this question a few times each year. Your 12,000 btu A/C is too big as Fred notes above to run very long.

If you install a small DC powered A/C (these were discussed some time back) in your state room, you could keep it cool overnight with inverter/battery power.

But then how are you going to recharge those 1,000 Ahs of batteries for the next night? You will have to run a generator with a very large charger to do it very fast. Your MT 36 does not have enough roof area for all of the solar panels it would take.

David

 

[mvweebles]

There are two missing bits of information: size of solar array, and as FF notes, for how long do you want to run your AC.

A 36-footer might (and I stress might) get 800W of solar. General rough-calc for determining output of a solar array is to multiply rated output by 5 (e.g. on average, will get equivalent of 5 solid hours of sun - in actuality, it's 2-hours in middle of day, then partial through the rest. Higher in summer, lower in winter - annual average is 5). So lets assume you manage to squeeze four full-size panels on your 36-footer and you end up with 1200W of solar. That means you can run your 1250W A/C at about net-zero for equivalent of 5-hours per day, maybe 7 in summertime.

Your battery capacity of 800AH is good for a dead-battery-max of 8-hours of AC running, probably closer to 5-6 because as FF notes, high discharge takes more out of the battery than slow drain.

So, Day 1, you have, at most, 12-13 hours of AC (solar and battery). Day 2, you have dead batteries.

In short: you have a bigger hole in your bucket than the hose can fill with water.

Peter

 

[Edpritt]

You guys are great!

QUOTE=mvweebles;961210]There are two missing bits of information: size of solar array, and as FF notes, for how long do you want to run your AC.
/QUOTE]

I just want to be able to knock down the temp in the aft cabin for an hour or two so the wife can be a bit more comfortable for bedtime.
My solar is 4-24v 200w panels.

 

[mvweebles]

You guys are great!

QUOTE=mvweebles;961210]There are two missing bits of information: size of solar array, and as FF notes, for how long do you want to run your AC.
/QUOTE]

I just want to be able to knock down the temp in the aft cabin for an hour or two so the wife can be a bit more comfortable for bedtime.
My solar is 4-24v 200w panels.

I have 800W of solar too, and 700AH of LiFePO4 battery bank. Pretty similar to what you're considering. I do not plan to run AC off batteries, but I might be able to run for 2-3 hours per day, at least on sunny days without running generator. But that's with a smaller AC (6k Btu - under 700W) in my v-berth cabin. Does not include the pump which are pretty energy hungry so needs to be sized appropriately.

Here's my energy budget. AC run-time is 15% duty cycle, so 3.75 hours. In all fairness, summer will probably generate more than the 4kw/day average production. Obviously, a good energy monitoring system will assist greatly.

Peter

 

[rsn48]

Google "Gone with the Wynns" solar for air conditioner. First you will need a "slow start" for the air conditioner unit. You might also Google "Gone with the Wynns" lithium set up, yours is small compared to theirs. They do run air conditioning off of solar but it is only for a couple of hours a day when they do use it.

 

[Ski in NC]

We run our aircon (on gennie) for a few hours in the evening to dry out and cool off boat. Bed time we shut it and gennie down and boat stays sleep-able til morning (most mornings, that is). This is in summer/fall in NC to Fla.

So with heat load minimal at night, the batts might last longer than the worst case 4-5-6hrs the calcs show (depending on how flat you let the batts get).

Also need to add in amps of pump if water cooled.

I don't get why not to run the gennie for a cabin cooldown. Best for gennies to run periodically.

 

[Iggy]

I have not seen anything on inverter loss. There is 4 to 8% on that too, yes?