Battery charging puzzle

Discussion in 'Motorhome Chat' started by Pharmbouy, May 30, 2009.

  1. Pharmbouy

    Pharmbouy Read Only Funster

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    I thought I knew all about charging batteries, solar panels etc. until a friend sent me this article written by an electrical engineer. I learned an awful lot more after reading it and still refer to this article quite often. I have reprinted this article in my website and pass it on to others at every opportunity.

    Tips and Tricks

    Just click (battery charging puzzle) at the top of the page.
     
  2. pappajohn

    pappajohn Funster Life Member

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    well i read 90% of the artical and its very interesting but.......

    for all the info he gives he doesnt tell you HOW to get the best from your panel and controller.

    plenty of info about.....'it needs to be adjusted to optimum 14.4v settings' but no info on how to adjust it.:Sad:
     
  3. pieterv

    pieterv Read Only Funster

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    That would depend on your charge controller. Some have no adjustment at all, some can be set for battery type, and the one he recommends (Trace C40) seems to be completely customisable.

    Pieter
     
  4. pappajohn

    pappajohn Funster Life Member

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    mine is very basic and non adjustable:cry: just an flashing led to indicate charging, but the point was he didnt explain how to adjust the trace 40 if thats what you have.:Doh:
    the chances of having an instruction book are pretty slim if it was already fitted when you bought the van.

    still a very interesting artical all the same:thumb:
     
  5. pieterv

    pieterv Read Only Funster

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    Yes, that is a fair point, although you could probably download one.

    I think he probably didn't want to get into details for one make of controller, when chances are you have a different one.

    His point that voltage adjustment is important is well made, I think. It took me quite a while to find a controller that could be set to the voltages that my battery specifies.

    Indeed an interesting article. (Just a bit of a different world from mine, looking at battery capacities and wattage of solar panels mentioned:Eeek:)
     
  6. pieterv

    pieterv Read Only Funster

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  7. walburga

    walburga Funster

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    Here's my input, and query :-

    I've just bought a stand alone 45 watt panel. I connected it directly to my 110 watt leisure battery and angled it to follow the sun (last week in the lakes !).
    I didn't use a voltage reg (havn't got one) as I thought I'd be the regulator if necessary.
    I regularly checked the voltage at the terminals and after approx 6 hrs the voltage reached 14.8 ( it started at 12.8 v). This was late afternoon, & it was sunny all day.
    Now according to this american chap 14.8 v is required to fully charge the battery, but 14.8 for how long ? And what if you say reach 15 ?
    Is there a bit of (very cheap) electronic kit that will stop the charge at 14.8 or is that why those solar regulators are so dear ?
    My roof mounted solar panel never gets the battery's above 13.4 volts.
    And all that power from 45 watts (at 14.8 volts) !

    regards
    Allen
     
  8. Pharmbouy

    Pharmbouy Read Only Funster

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    pieterv
    Yes we know Tioga George. Met him on our trip and visited for a couple of days. He is a great fellow. I follow his site regularly.

     
  9. Wildman

    Wildman Read Only Funster

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    the voltage you are reading is just above the battery voltage, (not the at rest voltage or open circuit voltage of the panel))however the open circuit charge voltage will be around 17V so chargeing quite nicely. Don't worry about how it works, the result shows it does.
     
  10. walburga

    walburga Funster

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    Hi Roger
    open circuit volts is just over 18 v in sunshine. I'm worried about cooking the battery if the voltage at the terminals is over 14.8 v. And how long can you allow it to charge at 14.8 v ?
    Also, what are the consequences of the voltage rising above 14.8 for several hours ?
    regards
    Allen
     
  11. Pharmbouy

    Pharmbouy Read Only Funster

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    I believe the ideal time for holding your voltage at 14.8 is 2 hours.
    If you go over the voltage of 14.8 for several hours, you will be entering the equalize stage which is up to 15.5 volt for 6 hours or so .
    I equalize my battery bank once a month.
     
  12. walburga

    walburga Funster

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    Hi Larry
    What is the 'equalize stage' ?
    I've just got the one leisure (habitation) battery, 110 watts.

    regards
    Allen
     
  13. pappajohn

    pappajohn Funster Life Member

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    equalization stage is a higher than normal voltage for a short time to breakdown any sulphation in the cells and allow them to accept an equal amount of charge across all the cells/batteries.

    BTW....your battery is a 110 Amp hour (AH)....not 110watt (W)
     
  14. walburga

    walburga Funster

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    So, is this equalization process a good thing ?
    It seems to me that if a solar regulator stops anything above say 13.4 v then the battery will never be fully charged, and also suffer from sulphation.
    Has anybody told the regulator manufacturers ?

    I stand corrected re amp hours / watts.

    regards
    Allen
     
  15. Sundowners

    Sundowners Funster Life Member

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    Hi Pharmbouy
    Thanks for that link, I don't have time to read all of it just now, I will try and print it out and try to digest it later.
    BTW it will be interesting to see if any of our lot succeed in benefitting from this info!!
    Nigel & Pamala
     
  16. gazznsam

    gazznsam Read Only Funster

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    it's very good info on that site, glad someone else agrees with me about the 14.8 volt thing... just been in an argument on a caravanning newsgroup about chargers, caravans come with a 13.8 volt power supply, that can charge the leisure battery....very very slowly, but they believe that going over 13.8 volts is a bad thing to do, the battery will gas, and you mustnt do that ever :Rofl1:

    i can't see a solar regulator cutting off at 13.4 volts... unless it's a cheap single stage one??? if so it's wasting a lot of that power you've paid to harvest from the sun.

    i have a 3 stage regulator made by steca, and it can be adjusted to different battery types, for gell cells its 14.4 volts, for wet cells it's 14.8 volts,
    and every month it'll try to do an equalization charge, where it takes the battery bank upto around 16 volts for hours... but you dont often get enough unbroken sun in a day to do that,

    but an equalization charge is really only of use to people with more than 1 battery... in a battery bank, because over time the batteries will get a little out of sync with each other, so an equalization charge stirs everything up and gets them all back in line... it can help on a badly sulphated single battery,
    but a proper pulsed desulphation charger would be a lot better, these send a harmonic to the battery which makes the plates vibrate above it's normal harmonic level, thus shaking off the bad stuff and mixing everything up...

    so they say, never tried one, my current batteries need one badly, but i'm not going to bother, my next batteries are going to be a couple of big elecsols as they are pretty much resistant to sulphation due to the fiberglass matting that holds the paste in place... but need to sell the bike before i can plump down almost 300 quid per battery (for the 270 AH ones)
     
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