Figuring out electric consumption

H35

H35

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25 Apr 2017
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Oslo, Norway
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Consumtion:
-Cooler w/external compressor. Nominal 31W
-Raymarine e7D MFD. 12W
-(Future) Raymarine radar 17/7W
-Lanterns, LED 10W
-VHF, stationary
Stereo. 2-4 hours pr day
-HAM-station (HF-radio) Transmitting at 100W
-Lights, LED Not much....
-Varme, Eberspãcher 3KW Water heater

Charging solar panels, 100W?
Motoring: 115A

So... My batteries are gone. Any good estimates on what size of a battery I will need?
 
My consumption is similar to yours.

Fridge
Water pump
Laptop
Phone
Eberspacher
Radio (sometimes all day)
LED lights
VHF, AIS, Depth, Wind, 3x4" displays, plus 12" tablet.

3 x 130ah batteries, 2 x 100w solar, 2 x 30w solar (very inefficient due to shading).

Not had the mains charger on since Feb. With 100w of solar probably need some additional input every 2 or 3 days, either mains or running the engine.
 
I don't have much space for more solar panels. But I suppose running the motor a little doesn't hurt. I could put an additional flexible 50W panel on deck though.
I am considering a 350A/h AGM. But it sure is heavy. And the sensible place to put it is weight sensitive.

LiFePo4 is an alternative, But a pricy one...
 
H35 said:
I don't have much space for more solar panels. But I suppose running the motor a little doesn't hurt. I could put an additional flexible 50W panel on deck though.
I am considering a 350A/h AGM. But it sure is heavy. And the sensible place to put it is weight sensitive.

LiFePo4 is an alternative, But a pricy one...
Click to expand...

I just went for 3 x 130ah lead acid batteries, less then £300 delivered.
 
Electrical consumption is a huge variable when you have a compressor fridge. Unless you like to jaw on radio transmission is not a huge drain because you transmit for such a short time. Receivers of course use some power and likely be on for much longer. You can do battery consumption over 24 hrs guessing at time usage like transmit and fridge using amp hour or amp minutes. Likewise you can guess the recharge power from your solar panel. But that is weather dependant.
So in the end you fit the biggest solar array you can reasonably fit on the decks. You fit the biggest batteries you can reasonably fit in. (or can afford) (buy 6v so they are more manageable weight wise when fitting removing.) From there you just have to monitor battery volts and start the engine or a recharge.
NB the bigger the batteries (all in parallel) the more charge you get form the engine alternator. Use an amp meter to find the point where charge current drops to the point where more charging is not worth continuing with. good luck olewill
 
You could use a data logger to measure the consumption over a set period.
Fluke do one but it will probably be expensive.

You would then have to run the test for various scenarios i.e. weather, guests on board etc.
 
Buy a DC clamp on meter, absolutley brilliant. Steady state consumption on Gladys with instruments, VHF, AIS receiver, running draws about 1.5A, and that increases to about 4.5A when the fridge compressor is running - which is about 3-4 times per hour for about 4 minutes each time. Internal lights are all LED and draw about 0.8A. Fresh water pump draws about 4 amps for less than a minute probably 5-6 times a day... but the clamp on confirms it all, and if your solar connections are direct to battery, you can measure the input from the separate connections...
 
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