12V Roof A/C

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   I just saw this product  but apparently its been available for a year or two. We know that air conditioners and heat pumps have advanced rapidly in the past few years, while our old noisy RV roof A/Cs remain horribly inefficient. Looks like there is a solution, albeit a bit costly. 
If it works as advertised and I did my math right this thing is over 2.5 times as efficient as my roof a/c was, and claimed to be quiet to boot. You would need to enlarge the hole in your RV roof a bit  but that should be doable. An no inverter needed for off grid use. 

This with now inexpensive lithium batteries and cheap high efficiency solar modules is bringing that holy grail of generator free boondock air-conditioning very close to reality. On an rpod sized RV with one of these, if you covered the entire roof area with solar and installed a couple hundred pounds worth of lithium batteries you could maintain it at a comfortable temp 24/7 except maybe in the middle of summer in the low southwest desert or south Florida. Total cost for the conversion might be around   $10k on a DIY install. Not terrible if summer boondocking is your primary camping objective.

https://mabrustore.com/products/mabru-12v-rooftop-air-conditioner-12000-btu-for-vehicles-campervans-rv-promaster-sprinter-transit

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offgrid Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290	Post Options Post Reply Quote offgrid Report Post Quote Reply Topic: 12V Roof A/C Posted: 13 Nov 2022 at 4:20am
	I just saw this product but apparently its been available for a year or two. We know that air conditioners and heat pumps have advanced rapidly in the past few years, while our old noisy RV roof A/Cs remain horribly inefficient. Looks like there is a solution, albeit a bit costly. If it works as advertised and I did my math right this thing is over 2.5 times as efficient as my roof a/c was, and claimed to be quiet to boot. You would need to enlarge the hole in your RV roof a bit but that should be doable. An no inverter needed for off grid use. This with now inexpensive lithium batteries and cheap high efficiency solar modules is bringing that holy grail of generator free boondock air-conditioning very close to reality. On an rpod sized RV with one of these, if you covered the entire roof area with solar and installed a couple hundred pounds worth of lithium batteries you could maintain it at a comfortable temp 24/7 except maybe in the middle of summer in the low southwest desert or south Florida. Total cost for the conversion might be around $10k on a DIY install. Not terrible if summer boondocking is your primary camping objective. https://mabrustore.com/products/mabru-12v-rooftop-air-conditioner-12000-btu-for-vehicles-campervans-rv-promaster-sprinter-transit
	1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold

hank*pod Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 06 Oct 2022 Location: PA Online Status: Offline Posts: 61	Post Options Post Reply Quote hank*pod Report Post Quote Reply Posted: 13 Nov 2022 at 1:57pm
	I doubt they've made that much of an efficiency improvement but only for a 12 volt system. They'd quickly introduce a 120 volt AC and people would be able t avoid the upfront cost of 500 AH of lithium.

offgrid Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290	Post Options Post Reply Quote offgrid Report Post Quote Reply Posted: 13 Nov 2022 at 2:56pm
	It's a product that's only really interesting for boondockers, if youre plugged in at a campground no one cares much about the efficiency. And if your boondocking, you'll need batteries whether it's a 120Vac or 12Vdc air conditioner, plus an inverter if it's 120V, so yet more money. There's really nothing unusual about the efficiency claim either, it's in the same range as several residential mini split acs that have been available for several years now. So it's not that this products claimed efficiency is so high, it's that the roof a/cs we all have now are terrible. They make them the same way they did 20-30 years ago because it's cheap and no one cares, or at least only a small market segment does. The ones that do are mostly the expedition rig crowd, and those guys tend to have money to spend on their rigs, so I think that is what this product is primarily designed for. It might also be of interest as a truck sleeper cab a/c so they don't have to idle their rigs to stay cool during rest breaks. There are several other 12 and 24Vdc a/c's designed for that market, but those are smaller units for cooling smaller spaces.
	1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold

hank*pod Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 06 Oct 2022 Location: PA Online Status: Offline Posts: 61	Post Options Post Reply Quote hank*pod Report Post Quote Reply Posted: 13 Nov 2022 at 7:12pm
	Well, the only reason I need a 3500 watt generator and not a 2200 watt model, for example, is the occasional need to run the AC unit that came with my R-Pod. Cut the AC down to 600-700 watts - whether AC or DC - and I could save a lot on generation or buy higher quality for the same money. So again, if it's a great idea why isn't there competition? I conclude it may be more hype than reality (cooling capacity may be overstated), but I suppose others can be the early adopters and let everyone else know how it goes.

StephenH Members Profile Send Private Message Find Members Posts Add to Buddy List podders Helping podders - pHp Joined: 29 Nov 2015 Location: Wake Forest, NC Online Status: Offline Posts: 6288	Post Options Post Reply Quote StephenH Report Post Quote Reply Posted: 13 Nov 2022 at 9:47pm
	I like the idea of the lower power use and that it would be quieter than the one I have. Being able to use a smaller generator would be nice, but I already have the larger generator. I don't know how long it will take for the newer technology to replace the old. Until the new becomes competitive in price for manufacturers, I don't see it happening.
	StephenH Happy is the man that findeth wisdom,... ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS

offgrid Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290	Post Options Post Reply Quote offgrid Report Post Quote Reply Posted: 14 Nov 2022 at 3:43am
	You can already run our existing air conditioners on a little Honda 2K, and you need roughly that size gen to run the microwave anyway. So I don't see much benefit in being able to go to an even smaller generator. The fuel savings from a higher efficiency air conditioner running on a generator would probably not be enough benefit to convince folks to spend about 2k$ or so more for. Mabru's posted efficiency numbers are very achievable. Theirs work out to an EER of 16.4 (COP of 4.8). In comparison, the Fujitsu 9000 BTU mini split (I happen to be looking at getting a couple of those for home use) specs show an EER of 18 (COP of 5.3). As we've discussed in another thread, heat pumps/air conditioners have advanced rapidly in the past few years. The good ones all use inverter technology with variable speed compressors and fans, which has resulted in a dramatic efficiency improvement. Mabru uses that technology in their unit. They are well known in the cruising yacht world for their marine units, which have a very demanding customer base. This product looks like their first entry into the RV world. I'm not trying to sell anyone on them BTW, and I don't personally know that their product works as advertised, just saying their claims aren't outlandish. If I was building a boondocking rig right now I'd certainly consider installing one. As for using a 12V unit vs a 120V one in a generator run use case, that woudnt require a large battery bank. The generator would maintain the house battery via the existing converter. But to me the real benefit is to be able to have ac with the generator off. Every state and national park I've been to recently has mandatory quiet hours when generator running is not allowed. In sections of some campgrounds generators are banned entirely. Not much is more annoying to tent campers than having to listen to someone's generator running all night while they're trying to sleep. I've been doing some tent camping lately and I won't stay in a campground where they allow nightime generator use. If your objective was to get through campground quiet hours while staying cool (rather than full solar off grid a/c operation) then the estimate I posted earlier would go down a lot. You wouldn't need solar at all and a battery about half the size would do. You would probably need to add a higher capacity or a second converter though so you could use more of your generator capacity when you are recharging, but those are pretty cheap compared to batteries and solar. Or you could add a high capacity circuit and charge from the tow vehicle alternator, and maybe dispense with the generator entirely. I don't see a product like this taking the broader RV market by storm either, the benefits are there but are pretty obscure for most folks. Maybe if someone packaged the a/c with a larger battery and sold it as nightime a/c system for quiet hour operation? But that's still really only going to appeal to a pretty small niche market. You probably have to have experienced sweating through some hot nights without being able to run your generator to appreciate the benefits.
	1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold