What size will do?

Discussion in 'Solar Power' started by wizzer59, Oct 13, 2014.

  1. wizzer59

    wizzer59 Funster

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    I store my hymer indoors on and off during the worst of the winter, so my solar panels won't work so I was thinking of running a lead to a small one outside, thing is how many watts is enough to keep em topped up? looking at this one(y)

    I think my leasure battery is 95amp and engine is about the same.
     
  2. Allanm

    Allanm Funster

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    That would supply about 1 amp or so on a really sunny day, nothing if it's cloudy.
    It may not be enough if you only need it to work in bad weather.
    Allan
     
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  3. JockandRita

    JockandRita Funster Life Member

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    Sorry Tim, I can't answer your question re "wot size".

    Can you gain access to a mains supply, to charge your battery once a day using a timer programmed for 2hrs, or once a week programmed for 12 hrs?

    Providing I didn't set the alarm whilst in storage, our Hymer (starter and hab) batteries were fine, even after weeks of the solar panels being covered in snow, ie, no charge. It is the alarm that's the killer when there is no charge available.

    Good luck. (y)

    Jock.
     
  4. John Laidler

    John Laidler Funster

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    You can get quite small chargers to keep batteries topped up, this one is just 6w, so a 20w panel could be enough.

    http://www.halfords.com/motoring/bu...tery-chargers/solar-battery-maintainer-12v-6w

    It isn't of course just a question of buying a panel, you would need the electronics to regulate the charge. Ideally you would want a charger specifically design for battery maintenance, the military use them for vehicles in long-term storage.
    They seem mostly to use pulsed charging, like this one:
    http://www.powerstream.com/solar-maintainer.htm (which is no longer available it say but it was the first link Google threw up)
    It might be easier to simply disconnect the engine battery and take it home.
     
  5. wizzer59

    wizzer59 Funster

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    Hi guys thanks for the replys, trouble is storage is in big closed barn on a farm and electric is not an option but I would not need the alarm so thats a bonus(y)
    I notice that little panel does not have a regulator so I'm wondering if its a little to powerful for maintance chargingo_O
    Cannot take the batterys home as the farmer keeps the keys incase he has to move the vans around if someone wants to get out(y)
     
  6. mitzimad

    mitzimad Funster

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    the only way you could answer the question is to know the discharge rate of the van when stationary and the input from the panel over winter
     
  7. pappajohn

    pappajohn Funster Life Member

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    What you forget is in winter the sun is minimal and unreliable.
    it can be days without any real sunshine, therefore no solar power......but the van batteries parasitic loads are constant whether the sunshine or not.

    A panel large enough to quickly recharge using whatever sun is available for whatever period is the only solar solution.

    As already said, 20w will give around 1amp/hr at very best in winter so say 6amps on a good winter day then maybe 5 or 6 sunless days.
    that just cancelled the 6amps of charge plus quit a bit more.
     
  8. Peter_n_Margaret

    Peter_n_Margaret Read Only Funster

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    During the winter the self discharge rate of lead acid batteries is lower than when it is warmer, so a bit of a top up once every few weeks in winter would be plenty.
    AGM batteries have much lower self discharge than wet cells and leaving them for 6 to 9 months or even longer (disconnected from all loads) is fine.
     
  9. John Laidler

    John Laidler Funster

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    All true, but I wasn't suggesting a solution for the leisure battery, only the engine battery. The leisure battery or batteries could be disconnected. Of course anything like an alarm on the vehicle would probably rule out a small solar charger. It all depends on the loads.

    I've seen hangers full of military vehicles all fitted with tiny solar panels and the only light available was through a few clear panels in the hanger roof. But these vehicles were fairly basic electrically speaking. I suspect there was zero drain on the batteries when they were turned off.
     
  10. dabhand

    dabhand Funster Life Member

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    Sorry to butt in on the OP but reading the above, when not in use, is it a problem to leave the van plugged in to the mains 24/7 as I do?
     
  11. JockandRita

    JockandRita Funster Life Member

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    According to the following article, by the very knowledgeable contributor, being plugged in long term may cause damage to some charging systems............or words to that effect. However, a timer as suggested above, would negate that scenario, and still keep the batteries topped up, (my suggestion, and not from the article).

    Have your hot drink in hand, and be prepared for some lengthy reading. ;)

    Cheers,

    Jock.
     
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  12. JockandRita

    JockandRita Funster Life Member

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