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Wednesday, May 6, 2015

RV Air Conditioning On 12 Volts? - Is That Even Possible?

My Rooftop A/C Control and Duct Unit
    I am a firm believer in Solar Power. Especially for RV'ers that enjoy Dry Camping or Boondocking without the noise of a typical generator. With a reasonable amount of planning and battery storage capacity, you can run just about everything in your RV from 12V Deep Cycle House batteries. This includes (with an Inverter) your TV/Video system. How long really depends on what you have in your battery storage bank. For example, I can run my microwave for about 20 minutes continuously on battery power alone. I wouldn't do that...it's not great for the batteries, but 2-5 minutes has been OK. I can go longer after the batteries are charged in the AM and I am using mostly solar power. The only thing remaining is the Air Conditioner.
Can that even been done on 12 Volts?

A Typical All In One Unit for  a Truck Cab
The simple answer is...Maybe. I have been researching various ways to make it work over the last couple of years and have founds some interesting products. The power requirements have dropped considerably, but I'm not sure it's viable....yet. There are a few manufacturers that offer 12 Volt air conditioning systems. The military uses them to keep Armored Personnel Carriers, tanks and the like cool. The main issue? AMPS! The very best of these air conditioners will draw 46 Amps every hour when on full cool (8000 BTU), then dropping down to 26.67 Amps at 50% to maintain. While the sun is up and my batteries are charged, I put out around 46 amps of power from my current solar panels. That would support the air conditions, barely. The real problem happens on the overnight. That's a lot of power. Especially if you, like me, only have two batteries (260 amp hours/2= 130 amp hours usable).


If you have to get through 6- 8 hours of no sunlight you'd need a bare minimum of 160.2 amp hours of storage to make it work. I don't. I really do not have the space to add another 2 Lead Acid batteries to get me there. Yes, I know that at night you should be using less power than the estimate since there is no sun heating your RV and temps usually fall at night. Still....it would be VERY close and you would be draining your batteries quite quickly. If you had a reasonably sized Lithium Phosphate pack (say 300-400 amp/hours or larger) it would be a different story. However these are still quite expensive (they work, but at a price). AND you need to make sure you have the Solar Charging capacity to maintain the battery bank.

My conclusion? Not ready for prime-time in your average RV. Getting VERY close, but not just yet. Your average RV Rooftop Air conditioner uses around 10.5-15 Amps at 120 Volts AC to put out between 10,000 and 15,000 BTUs. They work. But you need a generator or massive, impractical battery bank to run them. Let's hope for a true battery breakthrough in either new chemistry or the pricing for Lithium Phosphate. We're close....so close. Stay Tuned!

Be Seeing You...Down The Road,

Rich "The Wanderman"
www.thewanderman.com

2 comments:

  1. Rich, what about the Turbokool? Have you checked it out?

    ReplyDelete
    Replies
    1. Unknown,
      Turbo Cool is NOT an air conditioner. It's an evaporative cooler. It takes water...sprays it in a rotating "drum" and this cools air due to evaporation. While it can work well in dry climates, it won't give you "real" A/C chilled air. If the humidity is high...no cooling.

      Thanks,

      Rich "The Wanderman"

      Delete

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