Notices
Results 1 to 9 of 9
Like Tree1Likes
  • 1 Post By billvon

Thread: Battery for small solar panel

  1. #1 Battery for small solar panel 
    Forum Masters Degree DianeG's Avatar
    Join Date
    Nov 2013
    Location
    Ontario, Canada
    Posts
    504
    My family's cabin has no electricity. I have a small solar panel and a battery pack to run 3 3-watt curly lights, which is fine for my purposes. (I just want to get around the hazards of using candles and oil lamps all the time.) The problem I have is with the battery pack, which never seems to last more than a year. During the summer it is used a few hours total at night, maybe once or twice a week. I made sure it was fully charged or nearly so, either by the panel or plugging into an outlet at my house before using again.

    I've had it replaced 3 or 4 times, and have tried two different types. The first was a Motomaster Eliminator power box. Eliminator 600A/400W Power Box | Canadian Tire
    The second was Motomaster Nautilus Recreational power pack.

    I thought maybe the problem was not charging it regularly, but this year I was really careful to do that and it's dead yet again.

    Any idea what I might be doing wrong or an alternate solution?


    Reply With Quote  
     

  2.  
     

  3. #2  
    Moderator Moderator
    Join Date
    Apr 2007
    Location
    Washington State
    Posts
    8,322
    Sound't a bit similar to a cabin I hooked up for solar 3 years ago. I used a small marine gel-cell deep cycle battery. They are designed for long life and should last up to ten years.


    Meteorologist/Naturalist & Retired Soldier
    “The Holy Land is everywhere” Black Elk
    Reply With Quote  
     

  4. #3  
    Time Lord
    Join Date
    Apr 2008
    Posts
    5,338
    Canadian Tire is not known for quality. Besides that, could an Ontario winter damage this type of battery?
    A pong by any other name is still a pong. -williampinn
    Reply With Quote  
     

  5. #4  
    Forum Isotope
    Join Date
    Feb 2012
    Location
    Western US
    Posts
    2,666
    Quote Originally Posted by DianeG View Post
    My family's cabin has no electricity. I have a small solar panel and a battery pack to run 3 3-watt curly lights, which is fine for my purposes. (I just want to get around the hazards of using candles and oil lamps all the time.) The problem I have is with the battery pack, which never seems to last more than a year. During the summer it is used a few hours total at night, maybe once or twice a week. I made sure it was fully charged or nearly so, either by the panel or plugging into an outlet at my house before using again.

    I've had it replaced 3 or 4 times, and have tried two different types. The first was a Motomaster Eliminator power box. Eliminator 600A/400W Power Box | Canadian Tire
    The second was Motomaster Nautilus Recreational power pack.

    I thought maybe the problem was not charging it regularly, but this year I was really careful to do that and it's dead yet again.

    Any idea what I might be doing wrong or an alternate solution?
    Lead-acid batteries must be kept charged pretty much continuously. Regularly charging them is helpful, but allowing them to discharge periodically harms them permanently. So, you'd need to arrange for the charging circuit to maintain a "float" charge, or battery life will suffer.

    As Lynx_Fox mentioned, using a battery that is designed to more tolerant to discharge will help, but the best thing would be to keep the thing charged all the time, rather than periodically charging it up.

    Cold weather doesn't bother lead-acid batteries too much, as long as you don't allow the electrolyte to freeze. Repeated thermal cycling could cause mechanical stress-related problems, I suppose, but I never experienced any unusual wearout during the decade I lived in the northeastern US.
    Reply With Quote  
     

  6. #5  
    Forum Cosmic Wizard
    Join Date
    Aug 2013
    Location
    San Diego
    Posts
    2,006
    A "curly light" as in a compact flourescent? I've never seen one that's that small (3 watts.) Smallest I've seen is 6 watts.

    So let me do a rough calculation. You need 6 watts (my assumption on lights) x 3 lights x 4 hours a night. That's 72 watt-hours a night, or 6 amp-hours at 12 volts. That means a 12 amp-hour battery (never discharge below 50%.) For this I'd go with a 15 amp-hour alarm type gel cell. They are cheap ($30 or so) and should last either 500 cycles (charge/discharge) or 5 years, whichever comes first. I'd charge it with a 30-40 watt panel and a cheap charge controller. $120 and $30 respectively.

    Alternatively get a larger battery, or two of those in parallel, and charge it from an outlet every 2-3 days.
    Reply With Quote  
     

  7. #6  
    Forum Masters Degree DianeG's Avatar
    Join Date
    Nov 2013
    Location
    Ontario, Canada
    Posts
    504
    Thanks for the help. The bulbs really are 3 watt, equivalent to a 25 watt incandescent. Can anyone tell me how to check if a solar panel still works? How long should they last?
    Reply With Quote  
     

  8. #7  
    Forum Isotope
    Join Date
    Feb 2012
    Location
    Western US
    Posts
    2,666
    Quote Originally Posted by DianeG View Post
    Thanks for the help. The bulbs really are 3 watt, equivalent to a 25 watt incandescent. Can anyone tell me how to check if a solar panel still works? How long should they last?
    Aside from failures due to, say, failed solder joints/spot welds or mechanical damage, solar panels will have an extremely long lifetime. Their efficiency diminishes over time, but practical lifetimes are typically a couple of decades.

    To check a small-ish solar panel, illuminate the panel with whatever nominal lighting is assumed by the manufacturer, and check both the open-circuit voltage and the short-circuit current. Compare those values with the manufacturer's data.
    Reply With Quote  
     

  9. #8  
    Forum Cosmic Wizard
    Join Date
    Aug 2013
    Location
    San Diego
    Posts
    2,006
    Quote Originally Posted by DianeG View Post
    Thanks for the help. The bulbs really are 3 watt, equivalent to a 25 watt incandescent.
    A 25 watt incandescent is the equivalent of a 6 watt fluorescent (the ratio is about 4 to 1.) They may well be 3 watts, but if it were me I would be very suspicious and want to check them with a good ammeter.

    Can anyone tell me how to check if a solar panel still works? How long should they last?
    A silicon panel should last forever. An amorphous panel should last about 20 years.
    To test put in full sun. Connect a meter set to "DC volts" and read the open circuit DC voltage. Set it to "DC amps" and measure the short circuit current. Multiply those two numbers. That should similar to (not identical to, but similar to) the panel's power rating.
    DianeG likes this.
    Reply With Quote  
     

  10. #9  
    Suspended
    Join Date
    Apr 2007
    Location
    Pennsylvania
    Posts
    8,822
    Yep, there is such a thing as a 3 watt bulb. Incandescent replacement 20 watts, so they claim.
    MaxLite SKS3EACWW (70110) 3 Watt E12 Candelabra Base CFL Spiral UL Listed Compact Fluorescent Light Bulb CFL - Green Electrical Supply
    Reply With Quote  
     

Similar Threads

  1. Solar Panel questions....
    By Muto-kun in forum Electrical and Electronics
    Replies: 2
    Last Post: January 10th, 2014, 10:39 PM
  2. solar panel
    By kambanda fredrick in forum General Discussion
    Replies: 1
    Last Post: March 17th, 2013, 06:45 AM
  3. Is it Possible to Build Solar Panel At Home?
    By maive99 in forum Environmental Issues
    Replies: 23
    Last Post: February 14th, 2012, 07:41 AM
  4. If a Solar panel is used a house do you..?
    By Fmp2491 in forum Electrical and Electronics
    Replies: 12
    Last Post: February 7th, 2012, 01:27 AM
  5. Solar Panel Question??
    By craig86 in forum Physics
    Replies: 8
    Last Post: November 7th, 2007, 02:45 PM
Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •