# Stupid solar question



## midkiffsjoy (Sep 29, 2005)

Okay.....I have several OLD solar books, and am finding some great info on the net, but I'm stumped over the whole "a 60 watt bulb doesnt just pull 60 watts" thing and my brain has fried trying to figure out how much power it'll take to run my cd player, cell phone, maybe a plug in cooler while camping and am to the point of staring blankly into space. Can anyone explain in very small "Joy has had a brain sucking month" terms HOW to figure out HOW much "power" something (say a portable cd player) pulls, and how long I could run it on a battery. (I'll figure out how much solar it takes to charge said cd player battery thingy later. One step at a time).

Yeah yeah yeah....I know. I'm trying to THINK again. We can all smell the smoke. But at LEAST I'm stubborn about it and havent given up yet!!! giggle.

Thanks Everybody!!!

Joy
(I'm melting MELTING.......)


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## rambler (Jan 20, 2004)

Electric power is measured in watts.

To get watts, you take the amps used, times the volts.

A label on most every single electrical device gives you at least 2 of the above numbers, so you can figure the third.

However, those labels might be averages _or_ maximums. For example, something with speakers on it will use more power when set loud, as compared to whisper quiet.

But it will get you close.

So, a light bulb at 12v using 10 amps would be a 120watt bulb - volts times amps equals watts or power used.

A 120v bulb using 1 amp would be a 120 watt bulb as well - volts times amps.

--->Paul


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## Jim-mi (May 15, 2002)

The cd & cell are no problem, but the red flag is your loose term "plug in cooler"......
What unit--what curent does it draw...?

I've got a couple "plug in's" but their about useless because the small one draws 4 amps (12vdc)--24/7.
They will run a bat down in a big hurry.


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## jesset (Sep 6, 2006)

Hi Joy,
If you know how much current(amps) your cd player draws, say a 12v cd player drawing 10amps just to make figuring easier, if it was running off a 12v battery rated for 100amp-hours you would figure it out like this:
1) a 100amp-hour battery can discharge 1amp for 100hrs (1ampx100hrs=100amp-hours)
2) if drawing 10amps the battery will last 10hrs (10ampsx10hrs=100amp-hours) 
3) if drawing 100amps the battery will last 1hr (100ampsx1hr=100amp-hours)
The amp-hour rating is an industry standard but, you'll find out not all batteries are 
created equal and not all manufacturers think 1+1=2.

Jesse 
www.homesteadarticles.com


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## SolarGary (Sep 8, 2005)

Hi,

If you already have the CD player and other things you want to estimate the power consumption for, then one easy and accurate way to get their power use is to buy a Kill-A-Watt meter (about $30), and use the Kill-A-Watt to measure the power they use.
This will give much more accurate results than using the nameplate values on the appliance, because as Rambler pointed out the values listed on the nameplates are usually maximums.

You will find the Kill-A-Watt useful for all sorts of other things as well:
http://www.builditsolar.com/References/Half/KillAWatt.htm

Gary


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## midkiffsjoy (Sep 29, 2005)

Its been an .....interesting week. Sorry it took me so long to get back to ya'll. I have an awesome book on do-it-yourself wiring that actully made some sence to me. I really sux cause my dad was a master electrican and so was his dad, and step dad, and mom's dad, and I've been a "go to" helpping dad since I was 3 (really, no ----) but everytime I asked questions I got that whole "girls are stupid" look and then he'd make everything as technical as he could, and confuse the heck outta me. But some of its making sence now, and Ramber and Jesset both explained some simple things that I really needed explained simply to have it CLICK. grin.

I dont have the rates of everything yet because I wanted to figure out HOW to figure out how much a battery/panel could power before I decided WHAT to put on it. I dont know if I explained that right, but I'm one of those people that used to tick off my algebra teacher because I had to know WHY x = y so I could do it of my own later. (Poor Ms. Ragen....there was just no END to her annoyance with me....having to ACTULLY TEACH!!! giggle) 

Anyway....I have won a little kit off ebay for me and the kids to use to learn the basic principles, and much to my hubby's horror I have found a boat battery in the barn (no telling how long its been there) and am going to see if it'll hold a charge tomorrow to experiment with. When I feel we have learned enough to go from there I'm going to see if I can rig the box fan in the rabbit barn to a small panel, and rig the hubby's big wheel (recumbant trike...I LOVE welding!!!) to run the lights off a battery charged by a panel. 
Mostly we want to learn and then see what we CAN run off of solar on our farm (and maybe mobile). We are tired of being told that solar is not good for anything, and we have given up and are trying on our own. (As the local solar "expert" has told us to give up). 

Hey!!! I have ALL of Dad's electrican's gear, and pulled out a amphere ??? amp meter, that also had settings for volts, and I cant figure out how to use the darn thingy. I'm gonna look in some of my books again and try again tomorrow. I was trying to collect old bike parts today so I could build a little wagon to haul the kids in when I get my recumbant bike built. I'm driving Evan nuts cause I just LOVE customizing and I want to put turn signals on by bike and the little trailer. I'm having too much fun building them.

Thanks ya'll!!!

Joy


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## Jim-mi (May 15, 2002)

Do me one favor------whom ever that idiot is who tells you that solar won't do anything-----please put him/her/them on you ignore list----they really don't know for which they --babble--rant--speak.

I'll bet the thingy you found (from you dad) is an 'Amprob'......good for measuring AC.


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