Battery power consumption

[charles123]

I want to better understand my power consumption and wondered if there is a rule of thumb to calculate how much amperage I am using and therefore how much to put back in. I dont have any fancy equipment to monitor this only a volt meter on the instrument panel which I dare say is of little help in this respect

 

I have 540 amps in 3 batteries. 50 amp alternator and Sterling alternator controller

 

I want to add up the consumption in amps per day which is mostly taken up as follows

 

TV and satellite decoder 5 hrs per day

12 20w halogen lamps 7 hrs per day

Fridge 12 hrs per day

Pumps etc only an hour or so I would guess

 

As I say its only a rough guide I am after, hopefully some members of the board will have worked out a similar set of consumptions for their own boat

 

Thanks in anticipation

 

Charles

[DHutch]

What we have is center-zero amp-meter between the domestic batterys and the consumer unit.

 

This shows use at any time what going in/out of the battary.

- ie, usage minus charge.

 

We then also have a ampeter on the output of the alternaor, and the display of the charger. And a decent voltmeter.

 

This helps us to keep track of how much is going in/out at any one time, and a rough idea how much is in there.

 

 

 

As for working out your consuption per day, your've made the first step, of doing a rought audit on what your using and for how long.

- Then next step is to find out how many amps/watts each aplience is taking while its on.

- And keeping a cool-head with the units (watts/amps/volts/hour/mins etc)

 

So taking your list,

 

TV and satellite decoder 5 hrs per day.

- Say these draw 40watts between them (you'll have to look to really find out), which at 12volt is 3.33amps, for 5hours thats 16.7amphours perday.

 

12 20w halogen lamps 7 hrs per day, 12*20=240watts, which is 20amps, 7hours, thats 140amphours per day

 

Fridge 12 hrs per day, say its using about 2amps, for about half the time, thats on average 1amp contiuase, so 24amphours per day

 

Pumps etc only an hour or so I would guess, Pumps draw a lot (say 5amps), but i doubt you using it for an hour, so say it uses 2amp hours per day.

 

Add all of that up together, thats 182 amphours per day. So with a 540amphour battery bank, you should be able to run for 3days before recharging.

- However, you will nver get the full 540amphours out of your batterybank, certainly not without the voltage geting very low and damage to the bank occuring.

- So two days is proberbly a more realistic lenght of time.

 

 

 

And then, if you alternator charges at the full 50amps, right to the bitter end, it would take about 10hours running the battery to take it back upto fully charged.

 

 

 

Thats just a rough idea of the sort of thing you can do with more time and info.

-But it gives you a rough idea.

 

Hope it helps anyway

 

 

 

Daniel

[Gary Peacock]

You can find the calculators for this HERE

 

Hope this helps.