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marine/deep cycle battery question

Post in 'The Green Room' started by briansol, Dec 18, 2011.

  1. briansol

    briansol Minister of Fire

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    Ohms/wiring aside,

    Is there a significant difference between 1 100aH battery and 2 50aH batteries in terms of 'energy' or use time? The 2 50's cost more than 1 100 and weighs more too. I guess I don't understand the purpose of the smaller batteries at this point.

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  2. begreen

    begreen Mooderator Staff Member

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    It's been a long time since I have looked at this stuff, but my memory is that the plate thickness and quality of the battery is more important. Battery techonlogy can be somewhat confusing because there can be a lot of smoke and mirrors mixed in with the facts here. What is the application?
  3. briansol

    briansol Minister of Fire

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    Since nothing on the market is affordable, or lasts very long, I'm basically making my own back up 'UPS' power set up with a couple deep cycle batteries and a pure sine inverter, with both a grid trickle charger and off grid charge options like a solar panel and a generator.
  4. pyper

    pyper New Member

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    If you have 2 then you don't have a single point of failure -- that has both a good side and a bad side -- you have twice the odds that one will fail before it's time, but then again, if one fails you still have the other.

    I'd get the one, I think. Be careful about the hydrogen they produce.
  5. briansol

    briansol Minister of Fire

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    Yes, i've researched the gases issue. The sealed AGM type seem to be pretty safe. I will likely leave the battery bank on my deck anyway (my deck wraps-around the house, and is right by my chimney. Will make for an easy extension cord through a cracked window connection. As it's covered, it should stay out of the elements pretty good except when there's a nor'easter. I guess i can always use a tarp to cover it up. But that's logistics that i'll deal with once i get there. As of right now, i have 0 parts :)
  6. begreen

    begreen Mooderator Staff Member

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    You may want an insulated box that scavenges some house heat for the batteries. Their output decreases substantially at low temps. And Murphy's law says that's just when the power will fail.
  7. Jags

    Jags Moderate Moderator Staff Member

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    Usually a UPS will have more than one battery when a higher DC voltage is wanted. So to keep things simple - 1 100aH battery will produce 12VDC at 100aH. 2 50aH batteries will produce 24VDC at 100aH (in series). Real math proves out that it is not a true double, but you get the idea of what I am trying to show.
  8. Highbeam

    Highbeam Minister of Fire

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    Whoa! Seems to me that in the process of making 24 volts with a series arrangement that both batteries are using up aH at the same time so you will still only get 50 aH.
  9. Jags

    Jags Moderate Moderator Staff Member

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    ***Your logic would only provide 12V as well.*** <--Strike this from the records. :lol:

    Edit: you know what, you might be right, but I don't have time to look it up right now, So I will digress.

    Double edit: It is coming back to me - yes, you are correct. Double voltage - same capacity when in series. In parallel, it is same voltage, double capacity. Either way you look at it, it provides the same amount of power (p=I x E)

    (Good catch Highbeam).

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