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Old 02-01-2010, 23:45   #1
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How to Convert to Amp Hours?

I am looking at solar panels for my boat and am very confused about where to start with an electrical budget. I am under the impression I need to convert all appliances to amp hrs and do the same for a wind or solar panel to see if I can cover my demand.

How do I convert to amp hrs? For example if a solar panel has this rating, 6 Amps, 16.5 Volts (100 Watts), how many amp hrs is this equivalent to?

(This is the sunsei 6000)
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Old 03-01-2010, 00:15   #2
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Multiply the number of amps by the number of hours used.

So if your solar panel was used for 1 hour, that would be 6 amp hours; if used for 2 hours, that would be 12 amp hours etc.

Of course the solar panel won't supply 6 amps all the time so you will have to work the averages, lets say it averages 3 amps for 7 hours so you will get 21 amps hours.

Hope this helps
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Old 03-01-2010, 00:15   #3
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The general rule of thumb is you use about 4 hours for the amount of time you average the panel puts out full power for the day. So 6 amps times 4 hours is 24 amp-hours. If you want to get picky, they give two different amp specs on the spec sheet, short circuit and max power transfer. So the actual amps that you will see at battery voltage will be a little less. You don't have to worry about it since the number of hours is approximate and varies between 4 and 5 hours depending on where you live and who you talk to, this is just an approx number anyway.

If you were asking about appliances, 1 two amp light on for 2 hours is 4 amp-hours.

John
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Old 03-01-2010, 00:23   #4
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thanks for the info. What if I only have data in Watts? For example the Raymarine c70 says the power consumption is 9 Watts. How do i convert to amp hours?
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Old 03-01-2010, 00:28   #5
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Quote:
Originally Posted by fullkeel2 View Post
thanks for the info. What if I only have data in Watts? For example the Raymarine c70 says the power consumption is 9 Watts. How do i convert to amp hours?
power in watts = volts times current,

or amps = watts/volts

9/12 = 0.75 amps

next multiply amps times amount of time on in hours to get amp-hours.

John
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Old 03-01-2010, 02:08   #6
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If you haven't seen it, take a look at this thread...

Amp Hour Load Calculator - Did I Miss Anything?

Frank has a pretty nice spreadsheet for calculating loads, which you could modify to your situation.
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