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Old 30-08-2016, 21:31   #46
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Re: 12 Volt air conditioner may be availabe soon

Ok did a little google research and found a 9200 btu AC unit (RV) drawing 58.4 amps. running wattage 1270? numbers don't add up. (cycling?) I really want to find out if it would be feasible to keep a small queen berth cool all night without blowing through 400-500Ah. Someone has to have tried this before.
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Old 30-08-2016, 22:04   #47
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Re: 12 Volt air conditioner may be availabe soon

Here is an outside the box idea. I have one of these for our home, https://bedjet.com/ draws 40 watts and keeps you nice and cool. If you use it in heat mode is where it starts sucking down the power.
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Old 30-08-2016, 22:14   #48
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Re: 12 Volt air conditioner may be availabe soon

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Originally Posted by svGenesis View Post
Ok did a little google research and found a 9200 btu AC unit (RV) drawing 58.4 amps. running wattage 1270? numbers don't add up. (cycling?) I really want to find out if it would be feasible to keep a small queen berth cool all night without blowing through 400-500Ah. Someone has to have tried this before.
Search - trucker dc. A/C
Lots of different ones available both 12v and 24v
Battery up.
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Old 30-08-2016, 22:19   #49
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Re: 12 Volt air conditioner may be availabe soon

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Search - trucker dc. A/C
Lots of different ones available both 12v and 24v
Battery up.
Sorry , if you try ...
Trucker cab dc AC
That's better...
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Old 30-08-2016, 22:31   #50
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Re: 12 Volt air conditioner may be availabe soon

my AC is powered by a hand crank device. so it uses very little power. it's called a window latch!

it's only needed a few days a year.
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Old 30-08-2016, 22:42   #51
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Re: 12 Volt air conditioner may be availabe soon

Here's a wrightup I found on mother earth news about a guy running a 5,000 but haier window ac unit on solar he says it just uses 500 watts My Off-Grid Solar-Powered Air Conditioner
If the numbers work out it would be 500 x 5 =2500 watts so about 190 to 200 ah so best to have at least 1k of solar better with 1.5k
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Old 30-08-2016, 23:06   #52
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Re: 12 Volt air conditioner may be availabe soon

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Here's a wrightup I found on mother earth news about a guy running a 5,000 but haier window ac unit on solar he says it just uses 500 watts My Off-Grid Solar-Powered Air Conditioner
If the numbers work out it would be 500 x 5 =2500 watts so about 190 to 200 ah so best to have at least 1k of solar better with 1.5k
Hope Springs eternal. Thanks for that. I've been eyeing some 325 W panels and I think 6 an the back of the cat I'm planning on. That will give me let's say incase they don't operate completely to speck, 1800 W so I am sure I could sleep well in the tropics.based on your figures. Still going to try and have a 1,000 AH LithPo4 battery bank. Bye the way. I'm looking into buying direct from the factory a very well recognized battery. Works out about half of the marine sellers cost in the USA. Locally sourced 325 W mono panels are costing around $300 each. Through in a few thousand for electronics and I will have a pretty sound power plant afloat. Maybe I could run the boats full AC using the genset for a couple of hours or so. ..a few dollars a day on diesel would be worth the comfort from the AC.

Call me a wimp. But I wouldn't stay in a hotel without AC. So why not the same thinking for my boat.
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Old 31-08-2016, 04:07   #53
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Re: 12 Volt air conditioner may be availabe soon

Basic math. A 6000BTU a/c requires 1.7kW of power to operate for 1 hour.

It's not going to be practical to power that from a solar array & batteries unless you have a huge panel area and tons of storage. I.e. Not likely on your typical cruising boat.
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Old 31-08-2016, 06:41   #54
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Re: 12 Volt air conditioner may be availabe soon

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Basic math. A 6000BTU a/c requires 1.7kW of power to operate for 1 hour.

It's not going to be practical to power that from a solar array & batteries unless you have a huge panel area and tons of storage. I.e. Not likely on your typical cruising boat.
OK don't see your math working out correctly here

Quote:
Cooling Output: 6000 BTU
Room Size: 100-300 sq. ft.
Number of Cooling Speeds: 3
Number of Fan Speeds: 3
Finish: Smooth
Amps Required: 4.7 amps
Volts Required: 115 Volts
End quote

from the target website on the hair window unit
So my math says
4.7x115 =540 watts 540 watts by 12.5 volts nom = approx 44 ah
A far cry from your figure of 136 ah
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Old 31-08-2016, 06:58   #55
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Re: 12 Volt air conditioner may be availabe soon

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Basic math. A 6000BTU a/c requires 1.7kW of power to operate for 1 hour.
Point 1. kW is an instantaneous measure of power. An A/C will require the same number of kW whether it runs for 1 minute or 1 hour. Please learn the difference between power and energy and use the correct units.

Point 2. All of the figures that I have seen for 6000 BTU A/Cs use around 600 Watts or less. i.e. if operating at a 100% duty cycle, they will consume about 0.6kWh to operate for 1 hour.

Where does your 1.7kW come from?
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Old 31-08-2016, 07:16   #56
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Re: 12 Volt air conditioner may be availabe soon

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I came across this Kickstarter project for a 12 volt air conditioner. It only has a capacity of 1,100 BTUs. It might be enough to cool a small cabin.

I don't know anything about it except what I read on the Kickstarter web page. It is supposed to be available next year.

You can google Zero Breeze and find more information about it.


https://www.kickstarter.com/projects...ble-air-condit
A friend of mine had an open boat and he was hot running it so he installed a small air conditioner and ran a duct to a suit like one might wear bottom painting a boat. It kept him cool as long as he wore the suit.

This could work for that.

Regardless of the voltage, it takes an impractical amount of power to cool and keep cool the interior of a typical trawler or even a smaller boat without either a shore power connection or a running genset. It can be done but it's not practical in the real world.
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Old 31-08-2016, 08:22   #57
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Re: 12 Volt air conditioner may be availabe soon

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Originally Posted by GoingWalkabout View Post
I do believe you both are correct. Thanks.



Ok. Another solution is to have a second diesel generator at around 5KW. Have it connected to a separate stand alone for the main cabin. Run it all night. Depending on the cost of fuel.ut should cost somewhere between $6 and $9 each night.



Or set up your own large solar plant on board using high powered panels and a good Litho setup. Draw power from your 1000AH plus battery pack during the night and recharge early in the morning with the genset, run your water maker, hot water and when the sun is up shining well let your solar panels finish the power download into your Litho batteries off. Don't forget Litho.recharges much quicker than lead. Also since you should have some very large battery bank I would throw in a larger than normal alternator.



A hybrid power source system I think on reflection would be the best. You know you could give yourself carbon credits for the solar power you are generating which should balance out the diesel you are burning.



It's good to brainstorm solutions. I know I would love to have the best way to do this. I hate humidity.

My little 3.5 KW Diesel generator is good for right at 30 amps, my boat and most smaller sailboats have a 30 amp electrical system so no real need of having much more generator unless you have a 50 amp boat. It's electrical output running two AC's, the TV, fridge and all the other stuff is 21 amps on average, and it burns one quart of fuel an hour or four hours per gallon of course.
I will soon have a kilowatt of Solar and I have a large inverter, but I can tell you from experience that my little 5,000 BTU AC will chew through my 660 AH bank in short order. I feel sure I would need at least 2 KW of Solar and at least a 1000AH lead acid bank to run the little AC and that would just cool the front Stateroom, but one quart of Diesel an hour will cool the whole boat and run everything else and charge the bank too.


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Old 31-08-2016, 14:09   #58
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Re: 12 Volt air conditioner may be availabe soon

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Originally Posted by StuM View Post
Point 1. kW is an instantaneous measure of power. An A/C will require the same number of kW whether it runs for 1 minute or 1 hour. Please learn the difference between power and energy and use the correct units.

Point 2. All of the figures that I have seen for 6000 BTU A/Cs use around 600 Watts or less. i.e. if operating at a 100% duty cycle, they will consume about 0.6kWh to operate for 1 hour.

Where does your 1.7kW come from?
http://www.rapidtables.com/convert/p...TU_to_Watt.htm
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Old 31-08-2016, 14:42   #59
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Re: 12 Volt air conditioner may be availabe soon

ETA: now that I'm not just using my mobile device:

Point 1: ok, so I should have said kWh, big deal. Doesn't change the math.

Point 2: the figures for BTU/h to kWh is a well established number. Google it.

BTU to watts (W) conversion calculator

Yes, many air conditioning units claim certain BTU capacity and their stated amperage draws are less than you would expect based on the BTU conversion. So what. Just means someone isn't being truthful with their numbers.

At the end of the day what you care about is how long you can run a small A/C from an inverter. Say your unit uses 7A @ 120VAC, well it's going to draw AT LEAST 77A at 12VDC (probably more) so if it runs for an hour, you use 77Ah. Run it 6hrs a night and you're at 462Ah. So now you need a 1000Ah battery bank (not to exceed 50% discharge) and a massive solar array to put it back in 6hrs of sunlight. ITS JUST NOT PRACTICAL. Oh and by the way, who can realistically cool a boat with a 6kBTU air conditioner?
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Old 31-08-2016, 15:10   #60
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Re: 12 Volt air conditioner may be availabe soon

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Originally Posted by boatbod View Post
ETA: now that I'm not just using my mobile device:

Point 1: ok, so I should have said kWh, big deal. Doesn't change the math.

Point 2: the figures for BTU/h to kWh is a well established number. Google it.

BTU to watts (W) conversion calculator

Yes, many air conditioning units claim certain BTU capacity and their stated amperage draws are less than you would expect based on the BTU conversion. So what. Just means someone isn't being truthful with their numbers.

At the end of the day what you care about is how long you can run a small A/C from an inverter. Say your unit uses 7A @ 120VAC, well it's going to draw AT LEAST 77A at 12VDC (probably more) so if it runs for an hour, you use 77Ah. Run it 6hrs a night and you're at 462Ah. So now you need a 1000Ah battery bank (not to exceed 50% discharge) and a massive solar array to put it back in 6hrs of sunlight. ITS JUST NOT PRACTICAL. Oh and by the way, who can realistically cool a boat with a 6kBTU air conditioner?
I'll restate this again for clarity.

I'm looking for someone who has/is trying to AC or cool a queensize berth, (500 cubic feet ex.) using battery's (Li-PO) Solar (1000w-1200w) and a wind (400w) I expect my set-up to be 500-600ah Li-PO with 1000w solar, and 400w wind, Honda2000w as back up. I have seen people in RV's doing this but, they could easily spin thier genny, I'm looking for someone on a boat who is or has tried it.
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