Battery-powered AC units for truckers...?

[trumpetguy]

There are really two threads running here so let's not be confused. I am not using a generator...just batteries, a 2000w inverter and some elves. He he.



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[EllPea in CA]

Originally Posted by trumpetguy

....I am not using a generator...just batteries, a 2000w inverter and some elves. He he.



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To paraphrase what that lady in the deli said in "When Harry Met Sally," I'll have what he's having!

[Byron Kinnaman]

Originally Posted by trumpetguy

There are really two threads running here so let's not be confused. I am not using a generator...just batteries, a 2000w inverter and some elves. He he.



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OK no generator. How big is the wire going to the inverter? How big is the battery in Amp hours?

[Glenn Baglo]

Originally Posted by Byron Kinnaman

OK no generator. How big is the wire going to the inverter? How big is the battery in Amp hours?

See post #29.

[Mike Magee]

Originally Posted by trumpetguy

Hey ya'll. I am the Oliver owner running the AC with battery power. And regardless of what all the engineer types say it works. Now you may have an argument, but I have an experience. A key to this may be the Atwood Air Commander 13500, which is advertised to run on a Honda 2000i generator. I can attest to the fact that it will run on that small generator...even with a Propane carb, which I have.

So it occurred to me that if I could get past the LRA issue I could possibly start and run the Atwood using my 2000 W inverter and a transfer switch. I ran the unit on batteries for eight hours yesterday and it was close to 100 degrees. My Blue Sky remote showed 12 Volts and 93 percent full when I shut down.

I do have six Trojan T105 6V batteries with 362.5 usable Amp hours and they are connected with 4/0 welding cable. That does help. Keep those babies fully charged as in Handy Bob's blog and they will treat you right...

Ok, I'm not sure how you do this, either. But I'll take a stab at it. The A/C should be drawing 125A/hr while the compressor's running, but I don't know the draw when it flips to fan only; the key here must lie in the fact that the compressor is only running maybe 1/4 of the total runtime.

What about your panels? Steve said 360W of solar and 675 Ah of battery, but you say the batteries are only 362.5 Ah so now I'm questioning the accuracy of the solar number. If 360W of solar replenished about 18 A/hr, I'd guess that you might gain back about 200 Ah in a day of full sun. But if Steve accidentally reversed the numbers (meaning you have 675W of solar panels), that really might be enough to keep you charged close to full.

But one thing I did notice is that your remote shows 12V and 93% full. Those two bits of data seem to contradict each other. When your batteries are full they should be somewhere close to 13V, I think; 12V should be about 35%-40%, not 93%. Maybe you're getting a faulty reading from the remote on one number or the other?

As for the required starting current, I wonder if they put a repulsion-start motor on the compressor instead of a capacitor-start motor? Just speculation.

[Glenn Baglo]

Here's a table.

[Mike Magee]

Originally Posted by Mikmay

After further testing of the dometic fresh jet 3500 btu air conditioner on the HC1 we have decided that it is the best and well suited to use on the trailer. At 40 lbs it is the lightest and has the smallest footprint on the market. The unit will cool a 13 foot trailer in the calafornia heat to a comfortable temperature but will not turn the trailer into a icebox like the larger units did . Although it is an expensive unit it has a lot of features that other units don't .it has a dehumidifier , heat, led lighting and the ability to run on dc power with the inverter built specifically for the unit. This air conditioner works well with our trailer and I am not endorsing it for a larger trailer as we have not tested it on anything larger .

Mikmay, you mention CA heat. Can you be more specific? What sort of exterior and interior temps are we talking about? It would be great if you could pick a 95* day and turn the A/C on at mid-day, then time it to see how long it took to reach, say, 75*. The reason I ask is, I used to have a stick built trailer (14'L x 7'W x 6.5'H) and its 5K BTU window A/C was totally incapable of cooling the interior when ambient temp was much over 90*.

[Mike Magee]

Originally Posted by Glenn Baglo

Here's a table.

I'm familiar with those numbers, but wasn't exactly sure if the 6V Trojans would be the same. Hence the vague approximation.

[Mikmay]

Originally Posted by Mike Magee

Mikmay, you mention CA heat. Can you be more specific? What sort of exterior and interior temps are we talking about? It would be great if you could pick a 95* day and turn the A/C on at mid-day, then time it to see how long it took to reach, say, 75*. The reason I ask is, I used to have a stick built trailer (14'L x 7'W x 6.5'H) and its 5K BTU window A/C was totally incapable of cooling the interior when ambient temp was much over 90*.

Mike the reason I mention CA heat is that I think it is different than the heat in say in the Deep South or even here in Windsor were the humidity can make a big difference and we have yet to test it in those areas. I also made a mistake in saying it was rated for a trailer up to 7 meters when it is rated for a trailer up to 5 meters as I was reading the info on the larger unit. I also cool my trillium 4500 with a 5000 btu window AC and find it cools it to well so it could be the difference in ac units or the difference in trailer construction . There could be a big difference on the interior design of the Oliver, HC1 to other makes such as scamp or casita with carpeting on the walls that plays a part after all you will never see carpet on the walls of a walk in freezer. I'm not trying to say that one is better than the other as the opposite effect will probably happen in the winter.

[trumpetguy]

I just finished a three hour test running my Atwood AC just on batteries, with Solar disconnected and no shore power or generator. Thermostat set to 75 degrees, 95 degrees outside. I started the test at 13.2 volts and 100 percent full on the Blue Sky remote. Before the test I reset the amp hours to zero. After three hours the batteries were at 12.3 volts and the Amp hour meter recorded 146. With just over 350 AH in my batteries I am confident I can stay comfortable long enough to have a nap or a meal while traveling between campgrounds. If we have sun here tomorrow I will perform the same test with Solar on to record how many AH net after Solar are recorded.


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[Mike Magee]

David, very interesting! It's using about 50 amps per hour.

Can you tell us again how many watts of solar you have?

[Steve Outlaw]

Originally Posted by Mike Magee

David, very interesting! It's using about 50 amps per hour.

Can you tell us again how many watts of solar you have?

He has 320 Watts of solar and 750 amps of battery capacity (I multiplied wrong in my original post and stated them at 360 watts of solar and 675 amps of battery.) His statement "...With just over 350 AH in my batteries..." reflects the amount he has available to use without going below 50%.

[Mike Magee]

Nice battery bank! And more solar could be added if desired; but if it keeps up with the A/C, it will keep up with about anything.

[The Minimalist]

Originally Posted by Mikmay

Mike the reason I mention CA heat is that I think it is different than the heat in say in the Deep South or even here in Windsor were the humidity can make a big difference and we have yet to test it in those areas. I also made a mistake in saying it was rated for a trailer up to 7 meters when it is rated for a trailer up to 5 meters as I was reading the info on the larger unit. I also cool my trillium 4500 with a 5000 btu window AC and find it cools it to well so it could be the difference in ac units or the difference in trailer construction . There could be a big difference on the interior design of the Oliver, HC1 to other makes such as scamp or casita with carpeting on the walls that plays a part after all you will never see carpet on the walls of a walk in freezer. I'm not trying to say that one is better than the other as the opposite effect will probably happen in the winter.

When I noticed that the unit provides heat, I knew that it couldn't be resistance heat as that would draw too much amperage. I checked the Dometic site and found that, as I suspected, it is a heat pump. Air based heat pumps, in the summer time, as opposed to ground sink units, are trying to dump interior heat into hot outside air. In the winter, they are dumping interior cold into cold air. Despite having a basic knowledge of the physics, I'm still amazed that they work at all.

The comparison of CA temps, (I'm assuming we're referencing 'dry' heat) to deep south heat, I think would bring different results, as the humid heat we experience down South is saturated and I don't believe absorbs that dumped heat as readily as dry CA air.

Remember the old window mounted evaporative coolers? They worked much better in the desert southwest than they did in South Louisiana. Evaporation is a heat absorbing process. More humidity, less evaporation, less cooling.

Also, I wonder if Dometic actually has additional dehumidifying capacity in their units, or are they just touting, as a feature, the normal dehumidifying aspect of any cooling unit.

[trumpetguy]

Regarding dehumidifying. My Atwood has a Dry setting which cycles the compressor every six minutes when the temp is OK but you want to dry out the camper. I have not used this setting but it is good to have. Just to clarify my Atwood has no heating capability. None. We use our central heat when really cold and carry a small ceramic heater for chilly nights. I added a Spot thermostat which does a good job turning on and off. Not sure how this will affect the batteries, but will find out soon as we travel into the mountains in August.


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[trumpetguy]

By the way. Thanks Steve for helping with this thread. We stirred up a good conversation. Always a good thing.


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[Borrego Dave]

[QUOTE=The Minimalist;595428]
The comparison of CA temps, (I'm assuming we're referencing 'dry' heat) to deep south heat, I think would bring different results, as the humid heat we experience down South is saturated and I don't believe absorbs that dumped heat as readily as dry CA air. QUOTE]

I think you're on the right track as the AC unit is only one issue. The humidity/dry sure makes a huge difference on a body comfort.