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Nomad III

Jun 03, 2017

Testing running roof air via inverter

Testing running roof air from the battery bank with minimal solar.

Equipment:

Magnum 3012 hybrid inverter powered from 556 amp-hours of telecom batteries

Dometic 13500 BTU roof air from 2005 equipped with the Microair Easy Start

20170603 11 am cut in 24.6c (76.3 f) cut out 23.8 c (74.8 f) battery voltage 13.5 Ambient temperature 23.5 c (74.3 f)

When the air conditioner fan cuts in the red fault light flashes. In about 2 seconds there is a second flash as the compressor is started.
The amp draws are from the Magnum remote but no shunt is installed.

11:12 136 amps draw run time 2 minutes

11:20 132 amps draw run time 2 minutes

11:30 135 amps draw run time 4 minutes Ambient temperature 23.8 c (74.8 f)

11:41 136 amps draw run time 4 minutes

11:52 142 amps draw run time 2 minutes

11:55 air conditioner failed to start--low battery voltage displayed. Ambient temperature 24.4 c (75.9 f)

Plugged in shore power and battery bank is charging at 100 amps. Total air conditioner run time was 14 minutes in just under one hour.

12:16 bank charging at 51 amps.

These results are poorer than when I had marine batteries--but the total capacity of the bank is about 40% smaller. (size really does matter?)

32 Replies

Itinerant1
Explorer
Jun 03, 2017
Pianotuna interesting test with the AC. That is one thing that I haven't tried with my setup. If it starts getting warm enough for AC it's time to for higher elevation. If not possible then I hook up the small Honda gen to supplement.

Now using the microwave it has cooked many a meal for long periods with this draw. You can see this is being supplemented with a little solar.

Always interesting to see how other systems work.
RoyB
Explorer II
Jun 03, 2017
Good run Don.... makes me glad I can do without A/C hehe... Now Momabear is a different story.

We do pretty good camping off-grid without A/C but most of the time we are creekside somewhere and the noise of the running water really helps tricking the brain you don't need A/C haha...

I always feel like I am really doing something big here running 12VDC @ 25AMPS DC current for three or fours hours. Can't imagine running 150AMPS DC current doing anything in a RV...

Thats getting into the world of seeing battery cables twitch some...

Back in my high powered transmitter days we would run 5V Filaments at 160AMPS or so for each of five big RCA 6166A Electron tubes...

Roy Ken