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**a64pilot** · 26-06-2019, 14:15

Quote:

Originally Posted by kas_1611

Perhaps there in lies a solution to your energy problem. Put some big solar panels and maybe a wind generator on your boat to power your AC rather than use the mains. Or switch off all the ACs when you aren't onboard.

I love these posts. Let’s do some math shall we. Now I admittedly suck at math and am the type to misplace a decimal place etc. so check me.

He uses over 1700 KWH of power a month, but we will use 1700 to make it easier.
Now assume there are 30 days in a month and he uses 56.6 KWH a day.
That’s 56,600 watt hours if my math is correct.
We know by experience that panels will make 1/3 or their rated power in AH on a good Solar day. My 1,000 watts of panels are capable of 333 AH on a good day.

100 ah converts to 1,300 watt hours if we accept 13 V as our voltage.
Again check math.

56,600 divided by 1300 gives us 43.54
So we take this 43.54 and multiply it by 100 and determine we need to make 4354 AH per day?
Multiply that 4354 by 3 to get to watts and we see we need roughly 13,000 watts of panels on a good day, and of course a battery bank that can carry us through the night.

I’m sure there was an easier way to get there, and where I took us my not be right, I was sort of figuring it it out as I went along, and I’m no math guy.

Air conditioners require way more power than people seem to realize, that was the only point of the exercise, so does propulsion.

**a64pilot** · 26-06-2019, 14:21

To look at it another way, running my 16k and my 6k takes 20 amps of AC power, roughly that will convert to 200 amps DC.
I have 300 AH available to get to 50% of my bank SOC, so if we ignore perkuet (sp) my bank could hold air conditioning for 1.5 hours

FlyingScot · 26-06-2019, 14:24

Quote:

Originally Posted by a64pilot

I love these posts. Let’s do some math shall we. ...
He uses over 1700 KWH of power a month, but we will use 1700 to make it easier.
Now assume there are 30 days in a month and he uses 56.6 KWH a day. roughly 13,000 watts of panels on a good day, and of course a battery bank that can carry us through the night...

I’m sure there was an easier way to get there, and where I took us my not be right, I was sort of figuring it it out as I went along, and I’m no math guy.

Air conditioners require way more power than people seem to realize, that was the only point of the exercise, so does propulsion.

Using my panels as an example, they are good for about 1.5kwh per day per panel. 56kwh/1.5kwh = 37.

So the OP just needs 37 big 360 watt solar panels and to be located in the Caribe. Which is just about what you came up with. Plus battery bank, plus losses, etc.

TCM1968 · 26-06-2019, 18:10

I give up. Just wanted some actual real usage numbers from some who may have a similar set up to mine for comparison sake due to the fact that I had mentioned in my OP that we have only had the boat since February and I don’t have my own historical data for reference. But I appreciate all the science lessons.

Scubaseas · 26-06-2019, 18:23

If after you meter your consumption you find it less than what your bill should be maybe some of it is solar heat gain? My boat is smaller than yours and less windows I bet but mine also has a center cockpit but with a bimini over it. The solar panel is mounted on the dinghy davits (and has not a damn thing to do with A/C consumption) does shade the aft deck. Both areas that are being cooled are in the shade. The boat has some cheapy bubble wrap insulation in places. Your bill seems huge compared to mine which is only about 8 miles from you. I can PM you 10 months worth of electricity use if it might help?

sailorboy1 · 26-06-2019, 18:34

Isn’t it interesting with so many boaters at a dock getting meters electric no one knows the kWh they are using? It’s been 2 years since I’ve been on one so I don’t know.

It will be interesting to find out in the end what the op is using. But my bet is the marina is right.

TCM1968 · 26-06-2019, 18:34

Quote:

Originally Posted by Scubaseas

If after you meter your consumption you find it less than what your bill should be maybe some of it is solar heat gain? My boat is smaller than yours and less windows I bet but mine also has a center cockpit but with a bimini over it. The solar panel is mounted on the dinghy davits (and has not a damn thing to do with A/C consumption) does shade the aft deck. Both areas that are being cooled are in the shade. The boat has some cheapy bubble wrap insulation in places. Your bill seems huge compared to mine which is only about 8 miles from you. I can PM you 10 months worth of electricity use if it might help?

Thanks,
I may take you up on that. Friday when I get back to the boat I’m going to talk to the marina. Hopefully they just may have made an error.

motion30 · 26-06-2019, 19:58

I have a 44 foot mv. And this one 16000 BTU and one 12000 BTU running full-time my monthly electric bill was $192

TCM1968 · 26-06-2019, 20:17

Quote:

Originally Posted by motion30

I have a 44 foot mv. And this one 16000 BTU and one 12000 BTU running full-time my monthly electric bill was $192

Thanks but I need Kw not $ . Dollars depend on rates. Your $192 may be half my kw usage if your paying more than 10 cents per kw

Digdug · 10-07-2019, 08:38

Just put the unit in humidification mode. There is no need to run the a/c at 78 degrees all day. Consult the manual for your thermostat. You can set the parameters. First the fan will turn on for a set amount of time. The compressor will then run for a set amount of time. The unit will shut off for a set amount of time.

Here is how mine is set:
4 hours pass, the fan runs for 10 minutes and then the compressor turns on for 30 minutes. 4 hours later the process starts again.

This will keep the cabin from growing mold and having high humidity.

TCM1968 · 10-07-2019, 08:51

I have installed revenue grade meters on the boat this past weekend. I have started tracking the data and after 4 days on the boat we used 329kwh. I will have more data this weekend when we return and see how much is used while not onboard. My initial findings however are that damn these A/c unit suck some power! So my electric bill may be legit. But it will take a few months of data tracking to be for sure. I think I am going to start looking at the possibility of replacing the current units with newer inverter technology units.

TCM1968 · 29-07-2019, 13:00

Just a follow up since I last posted on this. This months bill was just a little over 1000kw. This included us being on the boat two extra days than last month due to the July fourth weekend. This bill seems to be on line from what my new meters are saying since tracking my usage. It’s a pretty large difference from the 1700kw used last month according to the marina. We spent more time on the boat and it certainly wasn’t any cooler than the month prior.

Scubaseas · 29-07-2019, 14:29

41' monohull in Seabrook Texas. 6.9cent/KW.

May was about 256KW usage on a 16000 BTU single Dometic Marne Airrrrr system. June was about 186 KW usage not on boat either month, t'stat set at 82*F.

July I lived aboard 3/4 of the month. T stat set at 74*F, 480KW usage. I suspect June was low due to minnows getting stuck in the water inlet which was a near daily occurrence in July. July was just silly hot and humid.

I can see 1000KW usage on your boat given bigger volume and windows. Still don't see why the 1700KW they hit you for.

**s/v Jedi** · 29-07-2019, 14:45

I don’t understand any of that and think you guys must be talking about kWh. KW is nothing but kW is a power level, not consumed energy which needs time factored in.

Anyway, you need to install a kWh meter on your boat so that you know what you used and can check the bill