RVelectricity – Just Ask Mike (J.A.M.): Solar-powered air conditioner update

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By Mike Sokol

Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM.


Dear Mike,
How is your solar panel air conditioner experiment coming along? Lots of us want to know if it’s possible and how much it will cost. —Andy

Dear Andy,
Like all technologies, there’s a point when the timing comes together with the price taking a nosedive and availability ramping up, but there are also technologies that are still in their infancy state which could take decades to become commonplace.

Take, for example, the now universal computer hard drive. We’re now used to slipping a tiny box the size of a pack of cigarettes in our pocket that weighs only a few ounces, draws just a couple watts of power, and yet holds terabytes (TB) (that’s more than a thousand-billion or 1,000,000,000,000) characters of information. Yes, and the cost of a modern 3-terabyte hard drive can be less than $100.

For a real eye opener, take a look at a 5-megabyte (that’s only 5 million or 5,000,000 characters of information) hard drive from 1956. This baby weighed over a ton and cost around $10,000 per megabyte (that’s $50,000 in 1956 dollars, which would be around $500,000 in 2020 dollars).

Haven’t air conditioners and refrigerators advanced?

Sadly, not by a lot since they were first invented and put into residential use some 100 years ago. Refrigeration technology still uses the same compressor/condenser/evaporator cycle first patented in the late 1800s and introduced for residential use in 1913.

Even though residential refrigerators made their debut more than 100 years ago, until electricity became widely distributed and cheap after the Depression-era building boom, the ice box still ruled many kitchens.

But once America (and the rest of the world) became electrified in the 1930s and ’40s, refrigeration became a staple in every household, with air conditioning following shortly thereafter. In fact, the world energy consumption of electricity for climate control (air conditioning) is currently around 12%. But because electricity has historically been so cheap there’s been little incentive to come up with a more energy-efficient air conditioner.

What about those batteries?

Well, batteries have come a long way since the invention of lead-acid batteries in 1859. But it’s only been in the last several decades that advanced battery chemistry like AGM (Absorbed Glass Mat) and Lithium (specifically Lithium Iron-Phosphate) for vehicles and RVs has become affordable. Even though the venerable lead-acid battery is 160 years old, it’s still the most popular battery chemistry for vehicles, simply due to cost and familiarity. But the times they are a-changin’, just not as fast as we might like.

What is my experiment?

I’m putting together a lab bench of an RV electrical system to test my mathematical model of solar/battery powering an RV air conditioner using the following components:

  • SoftStartRV controller
  • Dometic Penguin II 15kBTU air conditioner
  • CarGenerator SP2000 2 kW hybrid inverter
  • Briter Products BP12V100AH-S Lithium Battery
  • Xantrex 110W solar panel
  • REDARC BCDC 40-amp DC-DC Battery Charger and solar controller
  • Progressive Dynamics PD4560 – 60-amp converter/charger
  • Honda EU2200 inverter generator
  • Honda EX1000 inverter generator
  • CarGenerator CG1000 1kw inverter

Using this gear I’ll be able to create a test system that will power an RV air conditioner for perhaps 90 minutes or so from a single 100-amp-hr Lithium battery. With only a single 110-watt solar panel it will take upwards of 3 days of sunlight to recharge it. And, sadly, the cost of this type of upgrade will be a bit more than many of you are willing to pay.

So why do I do this sort of demonstration?

Well, I’m trying to create a scalable test model that will show just how many Lithium batteries, solar panels, and other tricks like the SoftStartRV, CarGenerator Hybrid Inverter, and Briter Products Lithium batteries are needed to run an air conditioner in your RV overnight without the benefit of shore power or a generator. That 8-hour window of sleeping in coolness is the holy grail right now.

Take a look at this vintage Fedders air conditioner ad bragging about sleeping inside of an ice cube on hot nights. I’m sure that looks pretty appealing when the air temperature is 100+ degrees inside of your RV and you desperately want to get some sleep. Yes, nothing ruins a night’s rest like trying to sleep in the heat.

When will I get an electric engine in my RV so I don’t have to fill it up with diesel or gasoline?

Well, I”m still waiting for my flying car like George Jetson had, and 2015 has come and gone without a Hoverboard like Marty used in “Back to the Future.” So an all-electric-powered car and RV may not happen in your lifetime.

Even if some exceptionally bright inventor comes up with a 1,000-amp-hr battery the size of a 3-TB hard drive that can fit in your pocket and only cost $100, we still would need to bump up the capacity of the electrical grid to recharge millions of these things at the same time. And I’m afraid that our current electrical distribution system isn’t up to that task until it’s completely replaced. So give the future another 20 to 30 years to happen at the current electrical grid replacement rate and maybe it will be ready in time for the $100 pocket RV battery debut.

Why am I such a naysayer?

I’m not. I’m just an engineer/scientist who understands physics and market forces. Until someone is willing to pay for the development of new technologies for batteries and upgrade the electrical grid, affordable all-electric vehicles (and Class A RVs) that have a 600-mile range that can be recharged in the time it takes to fill a gas tank are still a long way off, perhaps a few decades.

But the time is indeed coming, and I’m willing to help push the technology along as best as I can by educating the public on just what is real science, and what is a scam to separate you from your hard-earned money (like the EcoWatt). So when I hear about it, you’ll be the next to know about these new technologies from me. That’s a promise.

Learn more at the FROG Virtual Rally – Sept. 30 to Oct. 4, 2020

If you’re a member of FROG (the Forest River Owners’ Group), I’ll be teaching several RVelectricity virtual seminars during the TechnoRV FROG Virtual Rally from September 30 through October 4. I’ll be presenting a virtual JAM Session (Just Ask Mike) about what it takes to run an air conditioner from solar and battery power.

If you’re not already a member of the Forest River Owners’ Group and own a Forest River RV, you can sign up for free to become a member of FROG HERE.

This is a FROG members only rally

For more information on how you can attend this virtual rally along with lots of other seminars including the JAM Sessions that “yours truly” will be teaching online beginning September 30, please sign up for the TechnoRV FROG Virtual Rally HERE.

But if you’re not a FROG member don’t worry about missing out on these videos, as I’ll repost them the week after the rally on my own RVelectricity Youtube channel. So stay tuned.

That’s a wrap…

OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.

Let’s play safe out there….

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
Join Mike’s popular and informative Facebook group.
And you don’t want to miss Mike’s webcasts on his YouTube channel.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign

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Ken
29 days ago

I would expect that thermoelectric air conditioners would be on the market by now, but advances in that technology seem to be few and far between.

Last edited 29 days ago by Ken
Marcy Beard
1 month ago

We’ve installed a heat pump in our travel trailer – way more efficient and quieter than our old AC unit (which we took off the roof – more space for solar!). Would love to know what you think about heat pumps – they seem like the upgraded AC system you’re talking about

Bob P
1 month ago

Finally someone with common sense to put reality into ev powered vehicles that understands it will be a while before infrastructure catches up with technology.

Marion
1 month ago

Thank you for an objective, physics-based article. Love it!!! You have soothed my science soul which has been in full-anxiety mode for a while now. There is at least one other person out there that prefers science over pandering.

Dave
1 month ago

Good luck trying to update the power grid. Just kidding, but a few windmills should resolve the issue.

teubner
1 month ago

We have several members on Trek Tracks running mini split AC on solar and lithium.

Bill T
1 month ago

Great article Mike. The science & market forces statement explains it all.

Thomas Phipps
1 month ago

Politics over physics.