Gel Leisure Batteries

Discussion in 'Motorhome Chat' started by quickweh, Apr 27, 2013.

  1. quickweh

    quickweh Funster

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    Can anyone offer advice on how to check the condition of gel leisure batteries? My problem is that the batteries are fully charged (13.8V) at the end of the day by the solar panels but by the morning they show 12.5V and very quickly discharge down to 11.4 when blown air heating and TV are switched on , approximately 5 amp current draw. The batteries are 2 120 Ah Banner units which should give more than the one hour I got this morning. Posted on another forum, really need some guidance.:Sad:
     
  2. PhilandMena

    PhilandMena Funster

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    Right! I'll have a stab at this!
    When you put a load on fully charged batteries they will give a reduced output reading. The greater the load the lower the reading.
    When the load is stopped the batteries will continue to give a low reading and the after a few hours show their true condition. (This is likely to be higher than the reading you had when under a load).
    This may explain what you are seeing.

    Also, bear in mind if your pushing a lot of current into them you may well get a reading showing they are full when in fact they are not. Again they need to rest for a while and settle, then you can measure their true state.

    There's more!

    If you are relying only on Solar Panel/s to charge your batteries, be aware that:
    a, The size and condition of your battery bank.
    b, the amount of electricity you are drawing from your battery bank
    c, The size and output from your solar panel/s
    d, The weather conditions.

    All of the above will have an impact on your battery condition. so, if for instance you have one 100W solar panel fitted with a specified optimum output of say 7.5 amps it is highly unlikely you will get anywhere near that in the northern hemisphere and as a result you could be using more electricity than you are generating, resulting in low readings from your battery bank.

    Hope that makes sense.
     
    Last edited: Apr 27, 2013
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  3. maz

    maz Funster

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    The 13.8v reading is just the surface charge from the solar. You need to take a voltage reading across the terminals when the batteries have been disconnected from any charging (solar, EHU or engine) for a few hours. A fully charged battery will be around 12.7v. Are you reading the 12.5v off a control panel? And if so do you know this is correctly calibrated?

    What are you using (if anything) overnight on 12v? 11.4v is a seriously discharged battery so they may not be holding charge anyway and be kaput. :Sad:

    Is this by any chance the first outing since over-wintering the van? Or have the batteries been holding charge normally up to now, and the solar keeping pace with your usage?
     
  4. Gromett

    Gromett Funster

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    Agree with everything Philip said. I have also noted quite a few motorhomers have their van wired up to show the voltage of the batteries.... This means that if you have a solar panel you will be seeing the charge voltage not the batteries actual voltage. You will need to wait till at least an hour after the sun has gone down to see what the actual state of play is.

    The only way to judge the real state of the battery is to get something like the NASA or Victron battery monitor.

    With a solar panel connected you could see for example 0.4V higher on the battery terminal than the battery actually is. This is the charge voltage not the battery voltage. Then after the sun goes down and the solar charger switches off the voltage may drop a little immediately but there is a surface charge on the cells of the battery which will temporarily give the false impression that your battery has a higher state of charge.
     
  5. Jaws

    Jaws Funster Life Member

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    As you say they are gel batteries I presume you have also changed the charging system to accommodate them ?

    I get this all the time from bikers.. 'I have upgraded the battery to a gel one as the dealer told me they are better'

    Yessssss.. gel batteries are actually better but the charging of a gel is COMPLETELY opposite to a standard lead acid unit.

    A lead acid charging circuit has a floating voltage and a pretty constant amperage being delivered ( until such time as the battery voltage rises thereby dropping the drawn amperage )

    A gel battery charger keeps the voltage an absolute constant and the amperage varies

    Charging a gel battery with a standard charger will work, but severely reduces the life of the battery ( and I do mean severely )

    The info here is useful

    http://www.qsl.net/wb3gck/gel-cell.htm

    http://www.ehow.co.uk/how_5827578_charge-gel-cell-battery.html

    There is an awful lot more info available but I will not give you info overload :Wink:
     
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  6. pappajohn

    pappajohn Funster Life Member

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    a question John.

    do you also change the bikes charging system when fitting a gell battery ?

    the bikes alternator is set up for a flooded lead acid battery...not a gell battery so the charging regime will be incorrect.
     
  7. Jaws

    Jaws Funster Life Member

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    That is spot on PJ and is why I hear so much of it..
    No, people do not change the charging system and then moan like hell when their very expensive battery dies a death in about a year !!

    usually they last just long enough to be out of warranty and were bought either at Halfrauds ( who sell them as upgrades and actually have NO idea what they are either talking about or indeed care as long as the till rings up as much lolly as poss ) or from unscrupulous main stealers.

    I would think I have to deal with at least one problem a week like this..

    Usually it starts with 'there is something wrong with my charging as the newish battery keeps going flat'

    I talk the customer through all the tests to establish if it the genny or the reg rec..

    Once all checks are complete and all come back fine I THEN ask where the 'new' battery was bought from, what type it is ( often 'I dunno' is the answer ) and how much the battery was ( always a good indicator ! )

    If I simply ask about the battery first I can hear in the voice absolute disbelief.. so have to prove to the customer for them selves there is nowt wrong with the bike its self BEFORE telling them their expensive ( oft double in price ) battery is not suitable and is defunct !
     
    Last edited: Apr 27, 2013
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  8. Don Quixote

    Don Quixote Funster

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    I fitted the Victron battery monitor and it is the best thing in our MH. Well worth the money. I have 3 x batteries = 280Ah and the monitor shows me state of charge /discharge and best of all if the sun is out amount of charge from solar panel ( today 4.8amps when the sun came out ) or when the engine is running up to 14amps if I remember right.
     
    Last edited: Apr 27, 2013
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  9. quickweh

    quickweh Funster

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    Update!!

    First a big thank you for your help in understanding how my system works, a post on "another forum":Wink: pointed out that I have a pair of Banner AGM 90/110 AH batteries installed and a little research indicates that by having my solar charger control unit (CBE PRS240 unit) set to GEL may not have fully recharged my batteries. So sorry about the Gel question. I will check over the next week and put a 5 Amp load on for a couple of hours each morning and check the results. I will also check the terminal voltage each evening with the solar panels disconnected.
    Finally, there is a Thatcham security system fitted which has a small continuous current drain but I do not think that it is the problem, but I may be wrong there also.:Blush:
     
  10. Phill D

    Phill D

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    [/HI]

    that will normally be connected to the cab battery.
     
  11. maz

    maz Funster

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    Hope you manage to get to grips with your solar system and that everything will soon be working fine. The alarm would normally be wired to the engine battery so unlikely to be contributing to your leisure battery issue. Let us know how you get on. :Smile:
     
  12. quickweh

    quickweh Funster

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    AGM not Gel

    Thanks for all of the help and advice, it has been most useful. I have now checked each battery individually, taken readings after 12 hours disconnected from the system. The results show that the Voltage is initially OK and then "falls of a cliff" after an hour on a 4 Amp load. I have talked to Banner UK who advised that the batteries appear to be only part charged and would need 3 days of charging in order to be fully charged. So back to the charger with fingers crossed, will be expensive if not a charging issue.
     
  13. rainbow chasers

    rainbow chasers Read Only Funster

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    I get the same - to be honest, around 90% of people that come to me with Gel batteries fitted are having issues because they are not suitable for their use patterns, or incorrect charging system. It seems there are many outlets that are pushing them as a cure all problem solution - when half the time they make it worse as they are not suitable.

    Gels are good - but do consider your habits before buying one.....and don't waste your money buying them to cure a power drain - deal with the drain!

    What people have to remember with gels - they retain charge a little longer, but recover far slower than lead acid. If you are doing a lot of wild camping or off hook-up, then it may not really be the best solution. If you have a decent solar with regulated supply for a gel, then it should keep it topped up for moderate use - I always recommend users in this fashion to hook up every 3 days or so to give the gel time to recover fully.
     
  14. quickweh

    quickweh Funster

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    AGM not Gel

    Does this apply to AGM (Banner) batteries also? If so then this may be the reason for my battery voltage dropping away suddenly after a few days away at this time of year.
     
  15. rainbow chasers

    rainbow chasers Read Only Funster

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    AGM is a superior lead acid type. The cells are lined with glass fibre matting (absorbsion glass matt) and release power slower than standard lead acid batteries.

    I would treat them as a middle ground between gel and Lead - if they take longer to release, they will take longer to charge!
     
  16. quickweh

    quickweh Funster

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    Update!!

    Possibly a solution in sight:Smile:


    1) I contacted Banner who kindly agreed to test the batteries, it took 3 days!! The batteries were shot, a 10A load on their test rig gave 30 minutes of use on both units, not far off my findings. A big thank you to Banner who were very sympathetic and gave a good deal on a replacement pair.

    2) I contacted Vantage to check the manufacturer of the mains battery charger and discovered that the default setting for my model year was "maintenance charge" (float):Eeek: and not the 3 stage dynamic setting so there was no chance of the batteries being fully charged on mains from the time I collected the van. Two minutes with a screwdriver to change the setting and 14.4 volts on the replacement batteries. Needless to say this is not the case for current production. I checked with Banner who confirmed that this was almost certainly the cause because the mode of failure was identical for both batteries.

    Big thanks to Banner and all contributors to this thread. :thumb:
     
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  17. 1948

    1948 Read Only Funster

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    Banners batteries

    Fitted 2x AGM banners replacing 2 gel batteries ( 10 years old).
    Excellent service from banner help line Austria, on advise regarding charging .
    Also advised that one of the battery supplied was not right , got uk supplier to give me another one within half a day all arrangements done via Austria office.
    6 months in batteries Perfect performance.
    Good company., good products
     
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