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Thread: Battery power supplies - lead acid cells

  1. #11
    Join Date: Jul 2010

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    I'd worry about current flow from just one of those I have no doubt one of them could happily supply well over 1000 Amps for a short period as i have seen a car started with a 6Amp hour Yuasa
    Bests, Mark



    "We must believe in free will. We have no choice" Isaac Bashevis Singer

  2. #12
    Join Date: Feb 2008

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    12.8 V is fully charged, that's good, look like gel batteries, so need a charger that will not overcharge them.
    Spendorman

  3. #13
    Join Date: Oct 2008

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    Quote Originally Posted by nat8808 View Post
    Good point Mark! I wouldn't have thought of that cos it's just a harmless little battery... that could probably deliver 25 Amps or more, explode or burn the house down!
    When I was aged about 7 I accidentally shorted out a car battery while holding the wires between finger and thumb, an early lesson on messing with batteries and bulbs etc The Smell of burnt skin

    A couple of you tube of videos: ( I cant get them to embed for some reason)

    http://www.youtube.com/watch?v=-P4iaHPgmg8

    -
    http://www.youtube.com/watch?v=P11WbduMKhY

    -

  4. #14
    Join Date: Feb 2008

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    Quote Originally Posted by Reid Malenfant View Post
    I'd worry about current flow from just one of those I have no doubt one of them could happily supply well over 1000 Amps for a short period as i have seen a car started with a 6Amp hour Yuasa
    Yes, that current is quite possible.

    I've been near a lead acid battery explosion, was very nasty.
    Spendorman

  5. #15
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    Quote Originally Posted by spendorman View Post
    12.8 V is fully charged, that's good, look like gel batteries, so need a charger that will not overcharge them.
    They need a constant current charger, not a normal car battery charger. It needs to be regulated voltage wise & the batteries need to be charged at a maximum of 1/10th the amp hour capacity, better off at 1/20th for longevity.

    A 12V gel battery needs to be charged at 13.8V for standby use, i'm not 100% sure for continuous charge & discharge, i'll see what i can find but i think it may be a tad higher
    Bests, Mark



    "We must believe in free will. We have no choice" Isaac Bashevis Singer

  6. #16
    Join Date: Feb 2008

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    Quote Originally Posted by Mark Grant View Post
    When I was aged about 7 I accidentally shorted out a car battery while holding the wires between finger and thumb, an early lesson on messing with batteries and bulbs etc The Smell of burnt skin

    A couple of you tube of videos: ( I cant get them to embed for some reason)

    http://www.youtube.com/watch?v=-P4iaHPgmg8

    -
    http://www.youtube.com/watch?v=P11WbduMKhY

    -
    That's nothing to what can happen.

    At work I saw a large spanner dropped across the terminals of a large lead acid battery. Almost instantly it glowed red then bright red, someone levered it off with a broom handle. Spanner was completely bent.

    The battery exploding was a 300+ AH 36V (half ton in weight). There was virtually nothing left of it. Room was filled with smoke and acid fumes. The batteries were used in electric vehicles.
    Spendorman

  7. #17
    Join Date: Aug 2008

    Location: London

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    I'm Nat-andthat'swhyIdrink.

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    I'd best make sure they stay in their boxes and away from spanners of both the metal and human kind...

    Maplin do sell constant current chargers but perhaps not for this size - may have to splash out on something from RS.

  8. #18
    Join Date: Jul 2010

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    If you can understand this then you are doing better than me

    Cyclic charging regime for NP type gel batteries

    Cyclic charging.jpg
    Bests, Mark



    "We must believe in free will. We have no choice" Isaac Bashevis Singer

  9. #19
    Join Date: Feb 2008

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    Quote Originally Posted by Reid Malenfant View Post
    If you can understand this then you are doing better than me

    Cyclic charging regime for NP type gel batteries

    Cyclic charging.jpg
    That does look confusing, even after being on a lead acid battery/ charger training course! But that was about 25 years ago.

    I have a charger similar to the one below:

    http://www.sainsburys.co.uk/sol/shop...966984#infobox

    Can safely charge most 12V gel batteries as well as liquid electrolyte ones.

    Mine was only about £10 from Lidl

    Just found a pic of the Lidl one charging a battery:

    http://www.pistonheads.com/gassing/t...969.08575&nmt=

    Have to scroll down a bit to see it
    Last edited by spendorman; 18-05-2011 at 14:09.
    Spendorman

  10. #20
    Join Date: Feb 2008

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    Reading the spec of the Lidl charger, It says suitable for Gel or wet 12V batteries of 1.2 AH to 120AH. A "three phase-charging strategy" enablers the charging of the battery to almost 100% of it's original capacity. Furthermore, a long term connection of the battery to the charging station can take place to keep the battery in optimal condition when not in use without it being damaged in the process.

    There is a choice of currents, 0.8A or 3.6A and reverse polarity connection protection.
    Spendorman

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