Air conditioning

[Kevgrn114]

So I'm sitting in the parking lot in front of the texas parks and wildlife dept waiting for the current owner to get here to do the paperwork... I'm in my wife's hybrid highlander with the AC on hi because it's so hot n humid here.
Since this is a hybrid the engine cuts on and off as needed. What I noticed is it will sit for quite few minutes with the engine off and the AC on hi. So it is not using the engine to turn a compressor like normal engines... My though is, (finally) if the same type AC unit could be fitted to the Mac to run off batteries like the hybrid does. Although the hybrid does have a huge battery at about 250vdc I wonder how much juice the AC unit sucks up?

[Russ]

I believe Toyota hybrids use electric compressors for A/C. Therefore they don't require the engine to run the compressor.
However, it probably kicks the motor on when the battery drain seems excessive so as not to completely run it down.

A/C compressors use a LOT of energy. So do electric motors that can propel your hybrid motor free under 25mph. They can't do it for very long without large capacity batteries. Your Highlander kicks the motor on and off in minutes based on your description.

So yes, you can run an A/C on 12 or 24v battery banks, but eventually you will need to pay it back. That requires burning some fuel and a powerful charging system. Our outboards put most of the power to the prop and typically don't have a lot of charging capacity.

Duane Dunn was working on a genset powered hybrid propulsion system that he attached to electric props. Electric can be more efficient and you can run motors on large battery banks, but eventually you need to put it back.

I suppose you could do what you are describing with a 12v cooling system if you wanted to have large banks of batteries and a charging system like Sumner has with his alternator genset.

[Sumner]

... I wonder how much juice the AC unit sucks up?

Lots and impractical unless in a slip with AC available.

We just got home after living and working aboard the Endeavour up on stands in FL for over 3 months and the portable marine, high dollar AC that came with the boat, only cooled the cabin area down about 7 degrees below outside temps. Still 87 was better than 94 outside. The fact that these boats have no insulation means that they are very hard to cool or heat for that matter. Helps some though if they are in water and not up on stands where the 90+ heat hits every surface ,

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[Sumner]

...I suppose you could do what you are describing with a 12v cooling system if you wanted to have large banks of batteries and a charging system like Sumner has with his alternator genset.

Our gen-set....



.... and battery bank wouldn't be up to it either unless the AC unit was very small. The ....



http://purplesagetradingpost.com/sumner ... de-13.html

...GM alternator is only 60+ amps (could get ones over 100 amps, but the 5 HP Honda might not be enough for those). 60 amps X 14.1 volts is a max of 846 watts and it would probably burn up if that was continuous. I think the AC units would need more than that.

Best bet would be to find a place for a Honda genset, but I'd hate to hear that or ours run all night and then to store the AC and genset would be a pain. On a larger boat it could all be built in.

It got pretty miserable in the boat in Florida the last month (July) or so, but we never ran the AC at night. We used the ...



...same fan that we use on the Mac in the V-berth and on low always and we were comfortable with nighttime lows only getting to 80 or so. We started with the fan's timer on 2 hours but at the end of the stay we had it running 8 hours. The picture above is of course the Mac where the hatch and fan are forward of our heads. On the Endeavour the hatch is just above and aft of our heads and there we have the fan just below the hatch to blow air from there forward onto us and towards the foot area of the V-berth.

These fans...

http://purplesagetradingpost.com/sumner ... de-31.html

....work great and are very low amperage demand and the built-in timer even lowers the demand more as usually you don't need the fan all night,

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[Catigale]

Good rule of thumb....it takes about 1/3 power draw to move a given amount of energy with an AC type system....thus a 5000 BTU/hr AC will draw about 1700 BTU/hr of electricity....1700 BTU/hr translates to About 1500 watts power draw...not too practical at 12 VDC

[Crikey]

Probably cheaper to sail with twenty pounds of dry ice on board.

Watch the ventilation though....

[seahouse]

Any (automobile) A/C system has a residual capacity that allows some cold air to be withdrawn from the evaporator even though the compressor has stopped. I suspect that the hybrid system, in addition to using electric compressors, might also have been deliberately designed to maximize this “thermal inertia delay” effect.

I’ve now got my wife doing the following in her car (I've been doing it for years)…

Five minutes out from our destination, turn the A/C off. But turn the fan, which might normally kick off, to “on”, while maintaining the A/C controlled configuration of the ducts. (This might take some finagling with the controls to figure out, but I haven’t encountered a car yet that couldn’t do it).

You will continue to get another 5 to 10 minutes of cold, dry air, essentially for free, or for the cost of running just the fan, which might normally be running anyway. To do otherwise is to dissipate that energy as waste to the environment after the car is shut down.

The hybrid A/C system is a “pay me back later” system – the energy still has to be repaid when the engine starts and recharges the batteries.

Dry Ice Crikey? Was that a shameless attempt at “dry” humour.

-Brian.

[Ormonddude]

OK guys Learn Ohms Law a 5000btu ac units translates to about 550watts there are several small generators that could handle the load a lot better and quieter then that really cool alternator rig and a 1000watt inverter will run it on batteries automating all the switching would be a nightmare But lets see how I plan to handle it being as I live in Florida its sort of a must have at some point in time -
Now 2000watt generators should be your target there is smaller but most are two stroke engines and cant be ran for extended periods like while ya sleep. Here is my Ebay choice based purely on power weight and run time http://www.ebay.com/itm/320831492927?ss ... 1423.l2649 the premium companies make them as well but all have a shorter run time. Now here is where I show you just what a Cheap SOB I am I own this inverter http://www.ebay.com/itm/1000W-12V-DC-to ... 3cc9a7c4b3 and yes it works and yes it will run the AC. Now add your own batteries do your own math all the parts are there work with it use it - do it anyway ya want lol Oh and here is the AC I would choose realize down here in salt air its gonna burn up every couple of years and need to be replaced I would not get digital read outs or anything the slightest bit fancy its going to break.
http://www.lowes.com/pd_317014-2251-LRA ... BeanArray=[com.lowes.commerce.storelocator.beans.LocatorStoreBean%4075c475c4]&pl=1&productId=3204001&ipTrail=50.10.61.171&Ns=p_product_qty_sales_dollar|1&currentURL=%3FgoToProdList%3Dtrue%26Ns%3Dp_product_qty_sales_dollar|1

[kmclemore]

I’ve now got my wife doing the following in her car (I've been doing it for years)…

Five minutes out from our destination, turn the A/C off. But turn the fan, which might normally kick off, to “on”, while maintaining the A/C controlled configuration of the ducts. (This might take some finagling with the controls to figure out, but I haven’t encountered a car yet that couldn’t do it).

You will continue to get another 5 to 10 minutes of cold, dry air, essentially for free, or for the cost of running just the fan, which might normally be running anyway. To do otherwise is to dissipate that energy as waste to the environment after the car is shut down.

Brian, I do the same thing but for an entirely different reason. That evaporator coil (the thing that gets cold) condenses a LOT of water, and over time it begins to grow moldy. To help prevent this I cut off the A/C like you do - about 5-10 minutes before the end of a journey, leaving the fan on, so that it will heat up and dry out before I park it and let it sit. This helps a lot to keep that coil free of that moldy smell.

[Sumner]

OK guys Learn Ohms Law a 5000btu ac units translates to about 550watts there are several small generators that could handle the load a lot better and quieter then that really cool alternator rig and a 1000watt inverter will run it on batteries automating all the switching would be a nightmare But lets see how I plan to handle it being as I live in Florida its sort of a must have at some point in time -
Now 2000watt generators should be your target there is smaller but most are two stroke engines and cant be ran for extended periods like while ya sleep. Here is my Ebay choice based purely on power weight and run time http://www.ebay.com/itm/320831492927?ss ... 1423.l2649 the premium companies make them as well but all have a shorter run time. Now here is where I show you just what a Cheap SOB I am I own this inverter http://www.ebay.com/itm/1000W-12V-DC-to ... 3cc9a7c4b3 and yes it works and yes it will run the AC. Now add your own batteries do your own math all the parts are there work with it use it - do it anyway ya want lol Oh and here is the AC I would choose realize down here in salt air its gonna burn up every couple of years and need to be replaced I would not get digital read outs or anything the slightest bit fancy its going to break.
http://www.lowes.com/pd_317014-2251-LRA ... BeanArray=[com.lowes.commerce.storelocator.beans.LocatorStoreBean%4075c475c4]&pl=1&productId=3204001&ipTrail=50.10.61.171&Ns=p_product_qty_sales_dollar|1&currentURL=%3FgoToProdList%3Dtrue%26Ns%3Dp_product_qty_sales_dollar|1

We actually now have a second muffler (not shown on the web page) on the 5 HP Honda on our gen-set and it is quite quiet, probably quieter than the 68 db of the one you posted which is a lot louder than a Honda 2000 watt. The main problem is vibration noise down through the hull. These boats are like a drum inside. Also I was making the point that I didn't think our gen-set would be good at all running AC through an inverter. It was designed for only 12 volts as that is what the whole boat is set up for.

I'm also thinking that about any AC unit on the market is going to consume much more than 550 watts. The one you listed didn't list the amp draw as far as I could tell. Even 550 watts converted to 12 volts is about 46 amps and that doesn't take into consideration inverter losses. That would take a 90 amp/hour battery to less than 50% in an hour, so you wouldn't be on the battery long before the gen-set would have to cut in.

Good luck with your AC mod and please post back with results when done. If it works well there will be a lot of interested folks here,

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[Catigale]

Exactly. A 500 watt draw on a 12 VDC system is just not practical...