I purchased a Zero Breeze Mk2 portable air conditioner not really expecting too much.
A couple of thoughts to improve efficiency.The air conditioner is only 2300 BTU,m (effectively next to nothing)· maximum setting for this model.
Firstly you could parallel 2 or more of these for desperate situations.
It is always best to reduce humidity before trying to cool the air as such. The lowest fan speed on the coldest setting is the best desperate setting to reduce humidity.
Divide up an area with Velcroed up barriers to reduce the volume of the area you need to dehumidify. We have done this with our 3.5kW Dimplex RCAC & it has been effective.
We have built in a portable air conditioner in the roof as a temporary solution (15 years) until we can solve the issue of split system in our block of units.
It has worked surprisingly well with the 3.5kW Dimplex reverse cycle air conditioner which the area should have a proper 6kW system, top floor & large window area to the west.
What I have done is seperate the external condenser into the roof space. Then the internal side of things operate like a fully ducted system.
It has worked brilliantly over the years as far as cooling or heating. The only issue it that it simply is not the most efficient air conditioner. But it will cost $8k to get a proper split system in our situation. So amortised over a longer period, our temporary portable ducted system is more cost effective.
What you need to do is duct both intake & exhaust for the condenser to the outside. I am very surprised that manufacturers still do not provide a dual plumbing exhaust air system. I have been pointing out this issue for decades. It is very easy for the amateur (actual professional with real world skills) to solve, let alone a so called professional.
Dick0 said
10:56 AM Jan 15, 2023
Hylife wrote:
Hi Maids,
Ignore the pedantic little children and their immature ramblings about spelling.
As to your original post, a minor reminder about Ohms law may help.
Watts divided by volts = amps.
Now that all seems simple enough, BUT, you need to factor in that you are powering things from 12V DC not 240V AC.
So, ceteris paribus, we have to redo the math for the conversion, that is, everything has to be multiplied by a factor of 20 to get from 12 to 240.
If we assume that your inverter is a reputable pure sine wave model and it runs at about 80% efficiency, then we need to multiply things by a factor of 25.
Lets do some math now.
An Ibis 3 draws 5.7 amps on 240V AC on cooling (a little less on heating cycle). This is not taking into account the surge current of up to 40% when the compressor kicks in.
Using Ohms law in reverse we can calculate watts. Volts x Amps = Watts (nothing to do with the term of using Watts as a measure of cooling efficiency)
So, 240 x 5.7 = 1368 Watts
Times 25 to converts from 12V to 240V with inverter inefficiencies is the equivalent to 34,200 Watts.
Of course it is the amps that increases not the Watts, but that now means your Aircon is drawing 5.7 x 25 = 142.5 Amps from your batteries.
Most of us subscribe to the theory of never taking lead acid batteries below 50% state of charge for longevity.
In this case, your 240amps of AGM power (assuming again that they are in perfect as new health), are at minimum in 51 minutes.
Now remember that Latin phrase I dropped earlier on, it roughly translated means "all things being equal".
Unfortunately, all things aren't equal because the voltage of your batteries decline as their capacity does, meaning a higher current draw as the batteries decline.
Then there is the surge current of the compressor, then there is the need for a much larger inverter to cope with the surge current, etc, etc, etc.
Now, here comes the real kick in the pants, how long will it take to put all those amps back into your batteries with only 400W of solar?
The best you'll get, allowing for a more efficient southerly latitude of say below Hervey Bay (yes that's right, solar is less efficient closer to the equator), mid-day full sun from 400W of panels is about 12 to 14 amps.
Take into account the movement of the sun and no shade at any time and you'll get about 50 amps for a whole day into lead acid batteries.
So, that's 3 days to put back in what you took out in 51 minutes, without any other draw on the batteries from lights, phones, fridges etc.
Now you see why heating or cooling from 12V DC is just not a good idea unless you have sh!t loads of batteries and sh!t loads of solar to replenish them.
Hope this helps. Cheers.
Maids, Hylife has put the explanation at best clarity to your question.
Running the aircon is one thing but replenishing the batteries is another.
My solar setup, as described below, assists the batteries with high charge input from the panels.
I think with an RV and your solar setup it may be best to consider a gennie to run the aircon.
A 2.2kw gennie would be ideal for your situation and they are fairly "light" to move.
There are some easy start & good bargains around. As an example...
Welcome back Trailer Sailer, always good to read your interesting posts even though Im not a sailor .
Had to do a quick edit or i would have been sent to the naught corner .
-- Edited by TimTim on Sunday 15th of January 2023 07:47:15 AM
Thank you for your kind words TimTim. :) Regarding the Zero Breeze MK2 I absolutely agree that if trying to cool a whole caravan whilst hiding inside from scorching temperatures during the day then forget it. Having said that if not hooked up to domestic power or a generator you can pretty much forget using an air-conditioner anyway as most chew through power at a rate beyond what solar panels and a sensible amount of batteries can handle anyway.
Unlike many here our preferred mode of travel includes moving on most days or going walking or sightseeing if the weather is tolerable. Moving on in our truck and slide on camper ( with or without attached yacht ) means generally being in our air conditioned truck cab during the heat of the day. Its those long hot steamy nights that make life on the road particularly uncomfortable I feel. Sectioning off your sleeping area to the smallest possible comfortable size can allow the tiny Zero Breeze to do its work I have found. As these times seem to be relatively infrequent then being able to pack the whole thing out of the way I found is a great bonus. I had an old Ryobi One tool bag which fitted it perfectly and another for its charger and ducting piping. These fitted either in a hidden cupboard in the yacht designed for a blackwater tank (we use a porta potti with spare second base) and an overhead cupboard in our slide on camper and only bring it out for THOSE nights. :)
Its size weight and very low power draw have made it a worthwhile addition to our equipment. It does provide enough cold air to moderate extreme temperatures during the day but via cold air blowing directly on you not trying to cool the entire space.
-- Edited by Trailer Sailer on Sunday 15th of January 2023 06:12:03 PM
A couple of thoughts to improve efficiency.The air conditioner is only 2300 BTU,m (effectively next to nothing)· maximum setting for this model.
Firstly you could parallel 2 or more of these for desperate situations.
It is always best to reduce humidity before trying to cool the air as such. The lowest fan speed on the coldest setting is the best desperate setting to reduce humidity.
Divide up an area with Velcroed up barriers to reduce the volume of the area you need to dehumidify. We have done this with our 3.5kW Dimplex RCAC & it has been effective.
We have built in a portable air conditioner in the roof as a temporary solution (15 years) until we can solve the issue of split system in our block of units.
It has worked surprisingly well with the 3.5kW Dimplex reverse cycle air conditioner which the area should have a proper 6kW system, top floor & large window area to the west.
What I have done is seperate the external condenser into the roof space. Then the internal side of things operate like a fully ducted system.
It has worked brilliantly over the years as far as cooling or heating. The only issue it that it simply is not the most efficient air conditioner. But it will cost $8k to get a proper split system in our situation. So amortised over a longer period, our temporary portable ducted system is more cost effective.
What you need to do is duct both intake & exhaust for the condenser to the outside. I am very surprised that manufacturers still do not provide a dual plumbing exhaust air system. I have been pointing out this issue for decades. It is very easy for the amateur (actual professional with real world skills) to solve, let alone a so called professional.
Maids, Hylife has put the explanation at best clarity to your question.
Running the aircon is one thing but replenishing the batteries is another.
My solar setup, as described below, assists the batteries with high charge input from the panels.
I think with an RV and your solar setup it may be best to consider a gennie to run the aircon.
A 2.2kw gennie would be ideal for your situation and they are fairly "light" to move.
There are some easy start & good bargains around. As an example...
NEW GenTrax Inverter Generator Max 2.5KW Rated 2.2KW Pure Sine Portable Petrol 657664801483 | eBay
Thank you for your kind words TimTim. :)
Regarding the Zero Breeze MK2 I absolutely agree that if trying to cool a whole caravan whilst hiding inside from scorching temperatures during the day then forget it.
Having said that if not hooked up to domestic power or a generator you can pretty much forget using an air-conditioner anyway as most chew through power at a rate beyond what solar panels and a sensible amount of batteries can handle anyway.
Unlike many here our preferred mode of travel includes moving on most days or going walking or sightseeing if the weather is tolerable. Moving on in our truck and slide on camper ( with or without attached yacht ) means generally being in our air conditioned truck cab during the heat of the day.
Its those long hot steamy nights that make life on the road particularly uncomfortable I feel. Sectioning off your sleeping area to the smallest possible comfortable size can allow the tiny Zero Breeze to do its work I have found. As these times seem to be relatively infrequent then being able to pack the whole thing out of the way I found is a great bonus.
I had an old Ryobi One tool bag which fitted it perfectly and another for its charger and ducting piping. These fitted either in a hidden cupboard in the yacht designed for a blackwater tank (we use a porta potti with spare second base) and an overhead cupboard in our slide on camper and only bring it out for THOSE nights. :)
Its size weight and very low power draw have made it a worthwhile addition to our equipment. It does provide enough cold air to moderate extreme temperatures during the day but via cold air blowing directly on you not trying to cool the entire space.
-- Edited by Trailer Sailer on Sunday 15th of January 2023 06:12:03 PM