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connecting solar charger to 2 12V

Discussion in 'Alternative Energy' started by newhillian, May 20, 2009.

  1. Sceadwian

    Sceadwian Banned

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    If it was cold enough I'm surprised the glass didn't crack. Everytime we get a really super nasty cold winter here on the really bad days when everything has an ice scum on it you'll hear a story of some idiot that decided to pour near boiling water over the windshield of his car to get into work faster and ends up having to take the day off because his windshield turned into a spiders web sheet because of the thermal shock. I did something like that once when I was a kid, put a single drop of cold water on the top of a 100 watt lightbulb just to see what would happen. Damn near gave me a heart attack.
     
    Last edited: May 26, 2009
  2. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Now that sounds like a fun thing to do :D
     
  3. newhillian

    newhillian New Member

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    TCMTECH,
    Thanks for your response. I did some figuring and found that I would, on average, use about 16 amp hours in a day, and that only happens 2-3 times per month. The rest of the time, she is on the hard in a dry slip with no available electrical supply and about 8-10 hours direct sunlight per day. The batteries are brand new. This all sounds (to me) like a good recipe for keeping them topped off and alive. Does that sound like a fair statement to you guys.

    Oh, and my apologies for showing my keester in previous posting.

    Dave
     
  4. dave

    Dave New Member

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  5. Sceadwian

    Sceadwian Banned

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    Depends on if you leave the solar cell connected when you're not sailing 16Ahs at 12 volts is 192 watt/hours so your 15watt solar panel would have to be in full sun for 10 hours to recharge from a single use. I don't know what standard practice for lead acid batteries are so I don't know if it's safe to leave it connected all the time, if the solar panels output voltage is the float voltage of a lead acid pack it's probably safe to just plug the panel in when you dock and forget about it. I'm guessing the solar cell was designs specifically to keep 12 volt systems topped off, but I don't have the specs on your panel.
     
    Last edited: May 26, 2009
  6. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    I have heard that is very common with the RV travelers. They just put a small 10 -20 watt solar panel on their RV when its parked for extended periods and it keeps the big deep cycle batteries from going dead.

    As far as I have ever understood there is a safe minimum continuous current that can be put through any LA battery and never have any problems.
    I have heard and read several times its something like 1 -2 % of its AH rating. So a 100 Ah battery should not have problems with a 1 -2 amp trickle charge.

    But the 'Super ultra micro processor controlled multistage battery charger ophiles' will probably say different. :D

    I did not include any reference to an unobtainium based charge control IC description so I will likely be jumped for this! :rolleyes:
     
    Last edited: May 26, 2009
  7. Sceadwian

    Sceadwian Banned

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    I'm gonna go with it being safe too, if for no other reason it's not really going to be a constant trickle charge, aside from the obvious day/night cycle cloud and the angle the sun is hitting the panel at is going to effect current, so it's only going to be at the peak current for a few hours a day tops.
     

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