Sealed or Gel?

5 Posts

Nov 3, 2007 08:31 pm

Hello, I'm a bit new to alternative energy systems. I would like to know which battery would be best for my situation. I would like to power/charge my laptop for approximately three hours each day. The laptop consumes 15 - 20 watts. I bought a panel rated for 18 watts and assuming 3.5 hours of full sun, this would generate somewhere around 60 watts, about enough to run the laptop for three hours.

My question is, which battery type should I use in my system? I am planning on storing 3 days worth of solar power in the battery, since past experience with Virginian winters has proven not to be without some severe storms, mostly resulting in 2 days worth of power outage. I'm looking at either sealed or gel-cell batteries for my small system. Any advice would be appreciated!

- Jeremy

97 Posts

Nov 3, 2007 11:47 pm

Re: Sealed or Gel?

Hi Jerimiah, I am also new to alternative energy, but have some techinical background. I am assuming that you have a charge controller for use with your solar panel and proposed battery? The inverter that i am using, is compatible with either lead acid or nicad batteries (not sure all can be programmed for this), so it is important that your charge controller/inverter can recognize the battery type that you will be using. I am thinking that there is a wide variety of batteries on the market that would fit your capacity need, and its just a matter of finding one that fits your budget. Good luck. Smiles.

578 Posts

Nov 5, 2007 11:08 am

Re: Sealed or Gel?

AHHH!

units, the devil is in the details.

watts is a rate!

"The laptop consumes 15 - 20 watts. I bought a panel rated for 18 watts and assuming 3.5 hours of full sun, this would generate somewhere around 60 watts, about enough to run the laptop for three hours."

your laptop does not consume watts. think of watts like miles per hour. it is a rate. your laptop consumes at a rate of 20 watts. running for 3 hours it would consume 60 watt-hours.an 18w module produces at a rate of 18w at standard testing conditions, which is about 25% better than the real world. if you bought a pv module rated at 18w and your site was located in imaginery STC land , you could have 63 watt-hours energy production in one day.

now more math:

60 watt-hours per day load.

x2 = 120 watt hours of storage required for 1 day

x3 = 360 watt hours of storage for 3 days of load

/12v your assumed system voltage = 30amp-hours

which would be a battery like this.

http://store.altenergystore.com/Batteries/Batteries-Sealed-Agm/Universal-Ub12350-12V-34Ah-20Hr-Sealed-Agm-Batt/p1999/

i would not keep the battery outside if at all possible. certaily in some sort of enclosure, even if not fancy battery box.

james Alt-E staff

AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107 or +1.978.562.5858 x107
Fax: 877.242.6718 or +1.978.562.5854

184 Posts

Nov 5, 2007 03:54 pm

Re: Sealed or Gel?

Hi Jeremiah;

I noticed from your profile that you're 18 years old. If you're like my son of about the same age, cash is an issue. If that's the case, you can build a good battery bank from gell-cell batteries that computer departments discard. These are batteries used in UPS (uninterruptible power supplies) that have been replaced because of age, not because they're worn out. You can connect several of these in parallel, if necessary, to get the desired amount of storage capacity. Check with the IT department of any mid-sized to big business in your area.

John

5 Posts

Nov 7, 2007 02:50 pm

Re: Sealed or Gel?

Thanks! I plan on just starting with my room, so the battery will probably be kept there. I'm just going to start with a small system, and expand later on, so would it be ok to start with a larger battery?

And yes, cash is an issue, but I hope to recieve a grant from the science fair program at our high school to fund part of the project. I would gladly accept used batteries from companies, but where I live, sadly, there are none.

« Last Edit: Nov 7, 2007 02:53 pm by Jeremiah Simpkins »

578 Posts

Nov 7, 2007 07:15 pm

Re: Sealed or Gel?

i will see if i can look up some resources for you to use with your system. you should be reading home power magazine. there is a particular article from a few years back that talks specifically about taking one room off grid. as always the first step is to develop your loads list. then you will have real numbers to talk about and you will get better responses from the folks you ask because they will take you seriously and they will have real data to work with.

if you are going to go to school, check out my alma mater.
http://www.sanjuancollege.edu/documents/MathSci/RENG/content/REeFlyergfxlres.pdf

if you ever want scratch and dent stuff or used equipment, just ask, the worst we could say is no, and sometimes that stuff is kicking around here looking for a good home.

james - Alt-E staff

AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107 or +1.978.562.5858 x107
Fax: 877.242.6718 or +1.978.562.5854

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