Battery sizing question.

Discussion in 'Tech/Mech General' started by scotjimland, Nov 8, 2007.

  1. scotjimland

    scotjimland Funster Life Member

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    At present I have 4 x 85 ah house batteries and a Victron 70 amp charger, I plan to replace the batteries with larger capacity bank.

    Question:
    Is there an ideal opitmum battery bank size for this size of charger that I should use or should I just buy as big as I can physically fit .. I'm aware of charging times increasing with battery size, is there a 'rule of thumb' ?

    thanks in anticipation

    Jim
     
  2. GeorgeTelford

    GeorgeTelford Deleted User

    Hi Jim

    Yes for fastest charging, charger should be 20% of amp hour rating

    ie with 70 amp charger 350 Ah bank would be ideal (for fastest charging)

    However you could easily charge up a 700 ah bank with that charger, it would just take longer (way faster and better than any standard motorhome charger)
     
  3. Harley Dave

    Harley Dave Read Only Funster

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    70 Amp!! - that's quite a charger

    Was that fitted in the RV already or did you acquire it later?
     
  4. Digger Driver

    Digger Driver Read Only Funster

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  5. GeorgeTelford

    GeorgeTelford Deleted User

  6. GeorgeTelford

    GeorgeTelford Deleted User

  7. scotjimland

    scotjimland Funster Life Member

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    Thanks George, it was as I thought but always worth getting a second opinion ..

    I was thinking on getting 6 volt Trojan deep cycle batteries.. possible four of these http://www.barden-ukshop.com/t605-532-p.asp

    any thoughts ?

    Cheers
    Jim
     
  8. Digger Driver

    Digger Driver Read Only Funster

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    Well done George!:thumb:

    I stand corrected!:Blush:
     
  9. scotjimland

    scotjimland Funster Life Member

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    Hi

    I retro fitted earlier this year, the original charger was a standard RV unit..
    As George said, it's a Victron 70 amp / 1600 watt inverter .. brilliant bit of kit,
    works as a UPS supply, it 'tops up' a low amp EHU, you set the supply limit , say 6 amps, if you exceed that it pulls power from the batteries then recharges when the demand falls off ..

    Full Description here
     
  10. eddievanbitz

    eddievanbitz Trader - Funster

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    Hi Digger

    Did you mean twice as good? or twice as expensive? I agree that they are twice as expensive if not three times, but can't see why they would be twice as good.

    I personally would always go for a wet battery, with caps, so that I can check the levels and use a hydrometer. I have got battery testers costing hundreds of pounds, but I always trust my trusty hydrometer!

    Cheers

    Eddie
     
  11. Digger Driver

    Digger Driver Read Only Funster

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    Hi Eddie!
    After reading from the link George put up i am a bit suspect now!
    I know a lot of people who swear by them but i think they are more of a gimmick than anything else after reading up on them!
    Personally i have two Dumper batteries in mine (there free) and i have no trouble with them but i was thinking of getting gel batteries!
    George has just changed my mind!
     
  12. johnsandywhite

    johnsandywhite Read Only Funster

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  13. pappajohn

    pappajohn Funster Life Member

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    serious piece of kit but i couldn't warrant £800 for a battery charger and /or invertor. :Eeek:
     
  14. scotjimland

    scotjimland Funster Life Member

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    I was fortunate, I purchased it from a member on MHFacts, (he was upgrading to the next size up),
    I thought it well worth it as it cost little more than a new 40amp inteli charger.. :Wink:
     
  15. pappajohn

    pappajohn Funster Life Member

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    jeez........whats he done, ditched the engine and fitted dc motors to the wheels.:Eeek::Rofl1::Rofl1:
     
  16. scotjimland

    scotjimland Funster Life Member

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    Well, you should have seen his battery bank, not sure of ah size but it filled the void in the double floor of his Euromobile, he also had two 130 watt solar panels..
    He was planning on full timing in France and runs an internet hosting company depending on a Datastorm for communication, the wardrobe in the van was full of electronic kit..
    I don't believe he is a member here yet but if he joins I'm sure he will be more than happy to explain all .. :Wink:
     
  17. olley

    olley Funster

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    Hi jim I believe it was around 800ah. During the summer he was getting 16amps out of his solar panels around midday, and even running all his gear never seemed to have any trouble keeping his batteries topped up.

    That datastorm was a lot of trouble though, I just assumed you connected up and away you went, but he had quite a few problems that even with his programming knowledge he couldn't fix.

    Met him once at a rally, nice guy.

    Olley
     
  18. scotjimland

    scotjimland Funster Life Member

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    Hi Olley

    He spent about a week at the pub prior to going to France and assisted me to instal and configure the Victron. The Datastorm was giving him a lot of grief then and I believe he cut his France trip short due to problems with it..

    As you say, nice guy, haven't seen him on the facts for a while though ..
     
  19. Harley Dave

    Harley Dave Read Only Funster

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    Great link George, thanks - I had been thinking about a gel battery for the Bike but that site has put me right off and his simple explanation of the issues was very easy to comprehend.
     
  20. scotjimland

    scotjimland Funster Life Member

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    Thanks for the excellent link George, I only got round to reading it .. confirms what I always thought. :Wink:
     
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