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Author Topic: Operating A/C from an Inverter?  (Read 370 times)

Dreamsend

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Operating A/C from an Inverter?
« on: October 21, 2017, 11:24:51 AM »
Don't want to start a firestorm here, but I ran into some information stating one could operate typical air conditioning system in a TT from the batteries through an inverter when off the grid.  So just wanted to get some feedback from the good folks here.

A/C would be 13.5 K and the inverter would be a 3,000 watt (minimum).  I think, if I calculated correctly, that's about 25A per hour, and with inverter power loss ~28A per hour.  Correct me if this is incorrect please.

Believe it or not, I can't locate the electric service spec on the Outdoors RV I'm interested in, so I don't know if it's 30Amp or 50Amp.  If I have a choice, I'm going with the 50.  A dealer I talked with last week was supposed to get back to me, but hasn't.  Imagine that!

More info, the rest of the dreamed-of system would be solar panels with a lithium battery bank of ~600Ah and an inverter/charge combo.  Now I'm not talking about running the A/C even most of the day.    I'm looking perhaps to have the capability to use A/C maybe 1 to 3 hours if necessary just to cool things off late in the day for example.  The times of year and places I plan to be will be temperate, with nights down into the 50s and day highs in 80s.  BUT we all know weather, and know that excursions above or below our expectations can happen before one can get outa Dodge.  Also, my metabolism is pretty low, so I don't need things as cool as some of you "hot bodes" most likely do (LOL)

Also plan to have a Honda 2000 W generator.  I know I could add the companion Honda 2000W to that and run the A/C from generator, but I REALLY don't want the noise and the hassle of dong so.  Generator would be mounted in the truck bed.  Clouds, rain, dirt and or tree shade on panels are probable at times.

So far, my estimates of daily power consumption (since I've not lived in the TT yet) EXCLUDING A/C, looks to be about 215 Ah -- I like TV and will run fans to cool TT interior overnight.   Some of you may indicate that I'm doing overkill on the lithium battery, and that might be true, but all this is still very much in the planning stages so may change.  If practicable and useful to add on more battery or panels later (even portable type), I may start with a smaller system. 

So can one operate a 13.5K A/C from the 12V battery bank though an appropriately-sized inverter?  -- Assuming one is prepared to deal with battery charge and discharge rates of about 28A per hr, and not planning to operate A/C over 3 hours/day or so when off grid.

Your thoughts please.
Linda
Linda with kitties Sarah & Samson
2017 Ford F250 Lariat aka Gypsy Rose

SeilerBird

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Re: Operating A/C from an Inverter?
« Reply #1 on: October 21, 2017, 11:33:02 AM »
You might be able to operate the a/c from the inverter but it would only be for a very short time and you would be able to use no other electrical devices at the same time.
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QZ

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Re: Operating A/C from an Inverter?
« Reply #2 on: October 21, 2017, 12:06:26 PM »
Without digging deeper I'm guessing you are not multiplying the amps by 10. If an average 13.5 pulls 15 amps AC then it will pull 150 amps DC and much more at compressor start also add in inverter losses and you might use 160 to 170 amps in an hour. It's all about money and anything can be accomplished depending on how much you want to spend and how much roof space you have and how much hassle you want with storing a bunch of panels. A gen is hard to beat for high amperage  and you can cut the expense of large inverter and big battery bank then also use the genny for micro, hair dryer, toaster and coffee.

My resi frig pulls .6 at 120 v AC so the DC amps through the inverter that I see on my Trimetric is usually 6 to 7.  The LRC locked rotor current is 10 amps AC so the momentary DC spike at compressor start may approach 100 amps DC. It happens so fast that it isn't seen but it's very high.
« Last Edit: October 21, 2017, 05:21:52 PM by QZ »

grashley

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Re: Operating A/C from an Inverter?
« Reply #3 on: October 21, 2017, 06:06:52 PM »
QZ is right.  A 3000W inverter will supply 25A @ 120V, but requires 250A @ 12V to supply this power, plus conversion losses. 
Basic electricity - Watts = Amps X Volts.  A given device requires a more or less constant wattage to operate.  A 100W light bulb requires about 0.8A at 120V, or 8.0A at 12V.

It is possible, but to use 280amp/hours for an hour of A/C will require 600 A/H of battery (50% depletion) just for A/C.  Add another 200 A/H+ for normal operation.

It makes a genny sound pretty cheap!
Preacher Gordon
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AStravelers

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Re: Operating A/C from an Inverter?
« Reply #4 on: October 21, 2017, 06:14:06 PM »
Here are some links about Solar, batteries and running A/C off of battery:
http://www.technomadia.com/2016/06/running-an-rv-ac-off-solar-batteries-and-a-hybrid-boosting-inverter/

The following link is part 1 of 4 about solar and batteries along with some discussion of running the A/C.
http://wheelingit.us/2016/02/24/the-big-beastly-solarbattery-upgrade-part-i-why/

Bottom line:  Yes you can run the AC for a couple or three hours. If in full sun, maybe longer.   However you should have around 800+ amp hours (AH) of lead acid battery or 500+ AH of lithium.  Additionally 1000 watts of solar or more is best. 
Al & Sharon
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Drifterrider

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Re: Operating A/C from an Inverter?
« Reply #5 on: October 21, 2017, 08:10:15 PM »
Gone with the Wynns (YouTube) did a segment on running A/C in their "A" on batteries.

Yes you can:  if you have enough power.  The initial start up is a massive hit to the batteries but they mention something about a "soft start".

I believe they mentioned they have 800 amp hours of available power.  They have 1,000 watts of solar panels.   I think a generator would be much less expensive to buy and run.

However, the YouTube is worth a watch: and it is free.

Gary RV_Wizard

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Re: Operating A/C from an Inverter?
« Reply #6 on: October 22, 2017, 08:41:56 AM »
It is technically feasible but rarely practical. 
Gary
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Smokey613

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Re: Operating A/C from an Inverter?
« Reply #7 on: October 22, 2017, 10:21:59 AM »
As previously mentioned, doable just not practical.

https://youtu.be/B0rZY5uotKI

maddog348

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Re: Operating A/C from an Inverter?
« Reply #8 on: October 22, 2017, 11:50:59 AM »
Smokey ..  That is a totally cool u-tube.  Hope the OP takes the time to view it.  Don't think the average 'bear' has that much stuff in his picnic basket.  JM2  YMMV
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Kevin Means

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Re: Operating A/C from an Inverter?
« Reply #9 on: October 22, 2017, 12:23:38 PM »
Since 2014, Newmar has been offering an option on the King Aire (only $797,000.00) for 16 AGM house-batteries, which, when combined with a dedicated inverter, allows one of its three AC units to be run off battery power while traveling down the road. Presumably, it would also allow the AC unit to be run while boondocking (At least for awhile.)

The vast majority of RVs don't have the storage space for all the batteries it would take to run a roof AC unit for just a couple of hours, unless they were placed throughout the RV in different compartments, which in itself would be impractical. Like others have said, doable, but not real practical.

Kev
« Last Edit: October 22, 2017, 12:25:25 PM by Kevin Means »
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BruceinFL

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Re: Operating A/C from an Inverter?
« Reply #10 on: October 22, 2017, 02:22:38 PM »
For less than $1500, you can have a Honda 2000i and a MicroAir Soft Start on your ac and run your ac on the generator.
Bruce A.
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WILDEBILL308

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Re: Operating A/C from an Inverter?
« Reply #11 on: October 22, 2017, 02:37:53 PM »
Since 2014, Newmar has been offering an option on the King Aire (only $797,000.00) for 16 AGM house-batteries, which, when combined with a dedicated inverter, allows one of its three AC units to be run off battery power while traveling down the road. Presumably, it would also allow the AC unit to be run while boondocking (At least for awhile.)

The vast majority of RVs don't have the storage space for all the batteries it would take to run a roof AC unit for just a couple of hours, unless they were placed throughout the RV in different compartments, which in itself would be impractical. Like others have said, doable, but not real practical.

Kev
Some of the Prevost conversions have that two. They also have a second alternator for charging the battery bank.
The sad truth it's not going t happen for the OP.
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Dreamsend

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Re: Operating A/C from an Inverter?
« Reply #12 on: Today at 01:52:58 AM »
I gotta admit, I really didn't have my head on straight with that initial post.  WHAT was I thinking??? 

And you all have been so kind to take the time to provide helpful information, without pointing-out how screwy my reasoning was.  THANK YOU for that!

I see now my BIG mistake was using the A/C BTU as the wattage -- what a dummy.  But, you know, I knew the difference and thought I had checked the manufacturer brochure to make sure but somehow got off track anyway.  And I wasn't even enjoying my Crown Royal while going through the exercise.

So, back to the beginning.  All along in the planning process to go fulltime RVing, I didn't really plan on running an A/C off grid.  But, after running into info that one could conceivably do it, (I think it was likely the Technomadia site here recently) it got my wheels going in a different direction, and it appears I drove off a cliff.

I had planned to have a generator, but previously had not planned on having one large enough to handle a single A/C.  So the choices now are to either go with the initial plan of a single 2000W Honda, and get some experience on just how warm things will be and how often which is the KISS alternative (keep it simple stupid!), Then, if I find boondocking so enjoyable and easy that I want to remain off-grid even when things get too hot, add the companion 2000W Honda to it.  Or, simply head to a campground and plug-in.  Experience is likely the only way to find out what is gonna work for me.

As mentioned previously, IF, I want off-grid A/C, I would most likely plan on mounting the genny(s) in the pick-up bed, and build an appropriately ventilated and accessible enclosure for them - being able to add some sound-deadening material would be lovely.  47 lbs. (each) is about 10 lbs. beyond my lifting/carrying ability right now.  Time to work on upper body strength???  And maybe I should add more research effort and consideration into going with a 3600 Onan LP genny, on which I have only briefly looked into.  Since there is no dedicated compartment in the TT for an LP genny, is it feasible and workable to have one in the truck bed?
 
Since I'm going with lithium, which will be installed in the bunk bed area accessible from both the interior of the TT, and the exterior via a large garage door, that leaves the "normal" battery area behind the LP tanks on the hitch empty.  Sure would be nice if the gasoline generators could be placed securely (not grow legs) there and travel there without undo damage.   More research needed and more clear thinking on that alternative as well.

So once again, thanks for all the good discussion and helpful insights, i.e. keeping me on-track!.  It's getting time (~the next two months) to actually move forward with getting the TT, as there are none at dealerships right now, and I gotta find out about production schedules, dealing long-distance with dealerships, ordering if necessary, availability, getting it from Oregon/Idaho to Indiana, and what do I do with it once here?, etc. etc.   So knowing exactly how my power needs and management are going to work is a priority.  Thanks again.

Linda

 

Linda with kitties Sarah & Samson
2017 Ford F250 Lariat aka Gypsy Rose

SeilerBird

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Re: Operating A/C from an Inverter?
« Reply #13 on: Today at 04:13:43 AM »
Hey Linda, don't beat yourself up, we all make mistakes. That is the real beauty of hanging out on an online forum. You can get most of the kinks worked out here. Generators are big ugly, noisy, smelly, expensive additions to a TT. If you are going to buy one make sure you get one that can handle an A/C unit.
I would like to apologize to anyone I have not yet offended. Please be patient and I will get to you shortly.
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QZ

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Re: Operating A/C from an Inverter?
« Reply #14 on: Today at 09:40:51 AM »
We all learn as we go along so it's no big deal.  Far better to find out on here vs putting out money and having the system not work.   Look at this site. https://www.microair.net/products/easystart-364-3-ton-single-phase-soft-starter-for-air-conditioners?variant=30176048267. The microair is $300 but it isn't just another boost capacitor. I haven't tried one yet because I have a Honda eu3000si. My son has an older Honda EB3000C and it will not always start his AC so we may install one in his FW.

I built a metal cabinet for mine because I didn't have solar during our first year with our FW. It's really not needed but not knowing what I would run into I did a little extra. The number one questions is do you want to run the AC? YES, so the next question is do you want to run the microwave, hairdryer, toaster, vacuum etc on the genny? If NO then you need an appropriate battery bank and inverter. If yes then I would want the genny to be easy to deal with every day. I devised a way to bolt mine in front of my hitch in the truck bed which would take two people a considerable amount of time to remove.

I also wired in a transfer switch and 10 gauge cable so all I have to do is plug into the genny and it's ready to go and DW can use the remote start. Obviously the genny cant power the RV when I drive the truck away but I never really find myself in a position to need to do that.  We would all like to go without a genny but they are an very effective way to give us big amperage. They are extremely expensive if a person were to run it ALL the time as if you were on shore power. They are also a good way to sock the large amps into a low battery bank and then let the solar power finish the job. It takes a large solar set up to get 50 or 60 amps of battery charging when it is easy to do with most converters.

If you can run off a Honda 2000 and are sure that it will power the AC; I'd figure out a way to bolt it's underside mounts to the TT tongue and then maybe have someone fabricate a metal strap or frame that fastens to the TT and has to be removed with tools and a lock from under the tongue. Anything can be stolen but the easy fruit is picked first. The only issue with the smaller inverters is that they are usually not electric start so you have to go out and start it. You also want it mounted so that it's easy to fuel it and change the oil and maybe have some sort of solid piece of metal over the top to keep the rain off it.  I now just use a Honda vinyl cover when storing mine.

Depending on which direction you go with powering your heavy needs it will make a big difference in how much you need to spend on the rest of your equipment. If you are only powering televisions, phone chargers, laptops, led lights etc you can get by with far less battery and inverter. You could use AGM and not have the maintenance of wets and avoid the cost of lithium and use less of them too. I run a resi frig, 40 inch led television, two laptops etc and do it with six GC2 and a xantrex prowatt 2000 inverter. The inverter is a little large but at times I do make toast and run the hairdryer on it. I could probably squeeze by on four GC2 but six of them give me a large buffer for poor sun days or if caught in cold weather along with areas that I cant or dont want to run my genny around other people. 

I said that a genny is effective at what it does but I also believe in not making someone else have to listen to it all day so I now have a large solar bank. To cover all this ground these posts turn into a book so keep asking questions as you put your plan together.

Dreamsend

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Re: Operating A/C from an Inverter?
« Reply #15 on: Today at 12:11:40 PM »

Thank you Tom.  I heard once that one doesn't learn from the things they do right, only those they do wrong. Guess I'm still young enough to learn, thank goodness.
And QZ --- Your "booK' is now copied and pasted in a file for refresher reading.


I built a metal cabinet for mine . . . .The number one questions is do you want to run the AC? YES, so the next question is do you want to run the microwave, hairdryer, toaster, vacuum etc on the genny? If NO then you need an appropriate battery bank and inverter. If yes then I would want the genny to be easy to deal with every day.

I devised a way to bolt mine in front of my hitch in the truck bed which would take two people a considerable amount of time to remove.

Excellent to know.  Dimension for a single Honda 2000W are ~21x11.5x17.

If you can run off a Honda 2000 and are sure that it will power the AC;
No, pretty sure just a single 2000W will not run the A/C.  I'm calling manufacture hopefully today to find out just what the power needs are to reliably run the A/C in the TT I'm likely getting.  If I go the "yes I need A/C route upfront" - then it will be 2 Honda 2000 W.  Will investigate with manufact. if both could be fitted to a tongue mount like I'd desire.

I'd figure out a way to bolt it's underside mounts to the TT tongue and then maybe have someone fabricate a metal strap or frame that fastens to the TT and has to be removed with tools and a lock from under the tongue.

Pretty sure I can get some help with this -- Just want to make sure to design something that covers all the needs for safe and easy operating.

The only issue with the smaller inverters is that they are usually not electric start so you have to go out and start it.
The 2000s don't have electric start, but the 3000i model does.  Don't think the 3000 will be enough.

I said that a genny is effective at what it does but I also believe in not making someone else have to listen to it all day so I now have a large solar bank. To cover all this ground these posts turn into a book so keep asking questions as you put your plan together.
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Yeah, these technical things, get, well . . . technical and I know how much effort one has to put into writing this stuff clearly and correctly.  Much obliged.

I'm not likely to be a power hog and I can hold off doing some things if something BIG needs the power.  I am using lithium however, and will have an inverter/charger as well as some sort of generator set-up.  It's not an either or for me.  Just don't know all the exact details here, but everything is so much clearer now.

BTW - Honda is having a fall sale - 10 to 15% off portable models AND up to $200 instate rebates with their credit card.  A couple of dealers I looked at ARE participating.   Rebates end 10/31 if anyone is interested.  Sale ends 12/3/17.

All this planning makes me want to head out of the S&B and get on the road NOW.  Patience, Linda, patience!

Thanks again.
Linda with kitties Sarah & Samson
2017 Ford F250 Lariat aka Gypsy Rose

QZ

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Re: Operating A/C from an Inverter?
« Reply #16 on: Today at 12:37:01 PM »
The only issue with the smaller inverters is that they are usually not electric start so you have to go out and start it.
The 2000s don't have electric start, but the 3000i model does.  Don't think the 3000 will be enough
.

My eu3000si will run my 13,500 and sometimes run the micro too. I have forgotten and flipped the micro on and not tripped out but it probably depends on the compressor head pressure at that moment so I only run the ac.  If I wanted to run on a 2000 I'd be looking a the microair unit or if you want something more powerful in one unit  also consider the 3400 watt champion. The champ may be 3100 3400 or 3500 so research. People seem happy with them and they are much cheaper and maybe the 3100 will run the AC but research it first. There was a guy who was building Honda 2000 electric start kits but they were pricey and exotic.

I believe the owner was in an auto accident a while back so Pinellas may not be building them now. I didn't research, just got the link.

http://www.pinellaspowerproducts.com/view/heu2000isf/

Claims to run a 15,000 btu ac

https://www.tractorsupply.com/tsc/product/champion-power-equipment-100261-3400w-rv-ready-portable-inverter-generator-with-wireless-remote-start-1254676?cm_mmc=feed-_-GoogleShopping-_-Product-_-1254676&gdffi=71ecb2c5669d4bfa8a12ad37b4753469&gdfms=A92A36CD97094202A7AD28660B3D80A4&gclid=EAIaIQobChMIh5udkaOH1wIVgYdpCh3byANTEAQYAiABEgKmiPD_BwE

Yes, patience but it will all come together for you. That's why I mention flow chart. You need to think of some of this as a flow chart. It may not be perfect but it will help avoid costly mistakes.
« Last Edit: Today at 12:40:27 PM by QZ »

 

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