Battery discharging problems - any advise?

Discussion in 'Motorhome Chat' started by Freedom Hunter, Apr 15, 2016.

  1. Freedom Hunter

    Freedom Hunter Funster

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    We've just returned from 5 months cruising around Portugal. However, we hit a problem with our motorhome electrics. We have a 2010 Autocruise Starburst and fitted with a 120w solar panel (still the original battery). Until now the solar panel has always functioned fantastically and we have never had to worry about electric usage. For some reason, the battery charges fully over the day and as soon as evening approaches, within 10 minutes the battery totally discharges to zero - previously kept us easily supplied with electric overnight. We've removed the fully charged battery to our garage to test it and it is behaving as it should - retaining the charge as it used to do - for days. We've checked the Sargent unit and with everything in the motorhome switched off, it said it was only pulling 0.1amp - which is fine. We've cleaned the battery contacts and they are fine. We're assuming the battery is getting old and the cells breaking down, so maybe needs replacing. How long do batteries usually last? Any ideas out their would be gratefully received.......... Caroline
     
  2. TheBig1

    TheBig1 Funster Life Member

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    what you are reading is a floating voltage and the battery is likely now dead. Put it under load and it has no capacity. depending on the quality and the technology used batteries are good for 400-500 charging cycles. In an ideal environment a battery can last 10 years, but you rarely see that so on average 5 years for a leisure battery
     
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  3. tinkering

    tinkering Funster

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    Six years if you are lucky

    May I suggest you take the battery to a garage ,they will be able to test it in a few minutes
     
  4. Techno

    Techno Funster Life Member

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    How long is a piece of string.
    Every battery has a maximum number of discharge recharge cycles but this is often abused by over discharging and late recharging. So it could be a year or several years.
     
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  5. Techno

    Techno Funster Life Member

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    If you disconnect the battery completely and measure the voltage it will reveal all.
    12.7 volts is fully charged
    12 volts is flat
    below 12 volts is an incremental measurement of Fubar'd
     
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  6. andy63

    andy63 Funster

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    I have a feeling that what you have been seeing as a healthy battery is your solar panel voltage.. if your battery is dead after 10 min on load it sounds like its had it.... when you say zero what do you mean... it will have some measurable voltage..
    andy
     
  7. Freedom Hunter

    Freedom Hunter Funster

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    Many thanks for all your advise - fantastic! - well perhaps not, as it looks like a new battery is needed - it is as we thought. many, many thanks everyone....
    ps - any recommendations for a new battery, i know there are currently 3 types.....
     
  8. Techno

    Techno Funster Life Member

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    Depends on how much space you have? Is it crammed in, under a front seat or plenty of room.
     
  9. Techno

    Techno Funster Life Member

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  10. pappajohn

    pappajohn Funster Life Member

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    What everyones missed so far is........

    If it was indeed simply solar/charger surface voltage while on the van why is it holding charge on the bench.
    If the battery was completely cabbaged it would self discharge in a very short time.....or wouldnt charge at all.
    I would suggest the blocking diodes on the panel have failed allowing current to flow back to the panel at night....which is when the problem arises.
     
  11. Techno

    Techno Funster Life Member

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    That read to me like attached to a battery charger
     
  12. pappajohn

    pappajohn Funster Life Member

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    Possibly Andy, never thought of it that way.
     
  13. Freedom Hunter

    Freedom Hunter Funster

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    Many thanks Andy (Techno) for your battery recommendations - they look good and a great price!
    Regarding pappajohn's analysis - it seems good sense and as i've said it seems strange to me that on the bench the battery is holding it's charge - and the fault may actually be in the van. "I would suggest the blocking diodes on the panel have failed allowing current to flow back to the panel at night....which is when the problem arises." I do not quite understand this - being totally non-technical, just logical! I'm assuming that by "panel" you mean the motorhome control panel being faulty? Or are these diodes actually in the battery - sorry, as i say - none technical! My logic says that during the day and the electic is flowing 'in' to the panel/diodes and at night when there is no incoming flow, the electric reverses and flows out? Surely this is all controlled by the Sargent unit? Perhaps this may have acquired a fault, as at the end of the day i think this controls all the electric flow, whether input or output.
    I a loathe to buy a new battery if this is not the fault - though it is pretty old and has been well used - away for at least 5 months every year. My next thoughts are - who would I get to look at the van - just a motorhome mechanic or perhaps a mobile electronics expert?
    But many thanks again ......
     
  14. Freedom Hunter

    Freedom Hunter Funster

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    ....another thought - the Sargent unit is only showing showing a 0.1 drainage. When we disconnected the solar charging the Sargent slipped12.8 to 12.7 to 12.6 very quickly.....
     
  15. DavidG58

    DavidG58 Funster

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    I reckon I am pretty much with you on technical ability, but I think the reference to diodes is in the solar controller, to stop the battery sending power back to the panel in the dark (y)
     
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  16. Techno

    Techno Funster Life Member

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    The 0.1 drainage could be the battery itself due to a cell failure. Batteries comprise of 6 cells and if one fails the voltage when disconnected will drop to around 10.6
     
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  17. pappajohn

    pappajohn Funster Life Member

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    The diodes are part of the solar panel and prevent electrical current being sent back to the panel from the battery when the sun dont shine.
    The crystal cells on the panel will absorb any current and eventually flatten your battery.
     
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  18. Freedom Hunter

    Freedom Hunter Funster

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    Many thanks! Bit of controversy - are the diodes within the actual solar panel or the solar panel controller? Also, surely the Sargent unit should control the flows, so that this should never happen?
     
  19. andy63

    andy63 Funster

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    Do you have a dedicated solar charge controller in the system or is your panel wired through a Sargent built in charge controller..
    Only asking because of John's point about the panel blocking diodes... I'm sure my mppt charge controller has that function built into it to stop reverse current... so in my case I'm sure the controller and panel diodes would both have to be faulty for a reverse current to flow...
    Andy.
     
  20. shawn&emma

    shawn&emma Funster

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    As an aside to the original thread. How would I know if my solar panels have blocking diodes, is it just normal practice to do this? I am guessing that they do because my panels feed straight to the batteries and don't lose overnight. There was a little connection box on the back of the panel, should have had a nosey but didn't.



    Details On Solar Panel

    Dimensions - 1250 x 570 x 30mm. Longer, narrower, and 3% more efficient than poly.
    Specifications
    Open-circuit voltage (Voc) Av 22.1V, sd 0.3
    Voltage at maximum power (Vmp) Av 17.9V, sd 0.2
    Short-circuit current (Isc) Av 5.56A, sd 0.01
    Current at maximum power (Imp) Av 5.12A
    Maximum power at STC (Wp) 100W ±3%
    Operating temperature -40oC to +85oC
    Maximum system voltage 600Vdc
    Power tolerance ±3%

    Shawn
     
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