Charging 2 x Leisure Batts

Discussion in 'Tech/Mech General' started by Bulletguy, May 30, 2009.

  1. Bulletguy

    Bulletguy Read Only Funster

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    I have an 85ah Leisure battery and room to fit a 110ah in addition. Cabling is already in place which the previous owner wired in.

    Charging is via the usual split relay whilst mobile.

    Will this be adequate to re-charge the 110ah as well, or would i be better off running 2 x 85ah instead?
     
  2. Douglas

    Douglas Read Only Funster

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    You need an ammeter in line to check, don't guess, measure it!

    Doug...
     
  3. Brisey

    Brisey Funster Life Member

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    AFAIK both batteries should be of the same a/h rating and be of the same age. The older, lower rated battery will drag the good one down to its level.
     
  4. pappajohn

    pappajohn Funster Life Member

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    better off running two 110ah batteries if funds allow.:thumb:
     
  5. Bulletguy

    Bulletguy Read Only Funster

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    Heard this before but when i put it to the auto electrics guy at the battery place he said thats a nonsense....and no he wasn't bothered if i bought a battery from them or not. He still gets paid either way! What he did say, which seemed common sense, was the charging would take a bit longer than with just one battery fitted.

    I have an auto electrician locally who is 101% 'top notch' so i may well go and pay him a visit tomorrow.
     
  6. Bulletguy

    Bulletguy Read Only Funster

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    At £58 funds more than allow John.....it's space which is at a premium!
     
  7. hilldweller

    hilldweller Funster Life Member

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    If you have an old battery that has a high self discharge it WILL discharge a new battery strapped across it.

    The Past Masters of Battery are Fork Lift Trucks, Milk Floats, British Post Office and Submarines - maybe worth a Google using battery plus the above.
     
  8. Wildman

    Wildman Read Only Funster

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    the regulator will shut down the charge when the smaller amp/hr battery is fully charged, the larger one will never reach full charge. so a pair of 85 amp/hr batteries.
     
  9. gazznsam

    gazznsam Read Only Funster

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    apparantly it's fine to mix batterye sizes, the different internal resistances will sort out how much charge they accept so you wont over charge one and under charge the other, and they wont drain into each other or owt like that,

    what is likely to happen is that your mixing a new and an old battery, so the old un will one day die, and bring the total voltage of the battery bank down, dosent usually hurt the good battery if rectified in time, but if left unatended it can wreck both batteries.

    i have a 38 amp hour battery for my canoes lecky outboard, when i want to charge it i just connect it in paralell to my 460AH battery bank on a sunny day, or as i drive along (or the very rare occasion i am on shore power)
    i also do the reverse at the moment, when the main battery bank dies (as it's sulphated up badly), i connect the small battery and it gives me another night of power,
     
  10. derekfaeberwick

    derekfaeberwick Read Only Funster

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    That's how I red it as well. :thumb:
     
  11. hilldweller

    hilldweller Funster Life Member

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    You know what you are talking about but I can't see this.

    Both batteries are hard wired together, so for the charge to finish the pair must hit over 14V, so how can one not be fully charged. All I can think of is a significant difference in internal resistance, is that possible on two sensible sizes like 85+110Ah ?
     
  12. Bulletguy

    Bulletguy Read Only Funster

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    There does seem to be a great difference of opinion on this subject which i've noted before. No doubt by well meaning posters, and as i'm no expert auto electrician myself.....thats precisely who i'm going to see tomorrow.

    My alternative is removing the 85ah and 'squeezing' in the 110 instead.
     
  13. derekfaeberwick

    derekfaeberwick Read Only Funster

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    You said you had room for an 85 + a 110. SEEMPLES, 2x85. Job done. :Doh:
     
  14. derekfaeberwick

    derekfaeberwick Read Only Funster

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    Why ask then?:Eek!:
     
  15. hilldweller

    hilldweller Funster Life Member

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    Might not be the right person. Fine to trace a faulty part, find a short but his job is not to fully understand battery technology. For that you need a battery specialist. So for real data look to the makers.
     
  16. Bulletguy

    Bulletguy Read Only Funster

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    I can assure you Mark is the most reputable and highly respected auto electrician in this area. No young 'upstart' either. He has run his one man business for years.

    He said 85ah + 110ah not a problem as long as both batteries are in 100% order (ie pref. new or bought together at the same time). What he did say though is that leisure batteries do not last as long as convential main starter batteries due to the heavy discharge/recharge cycle. His advice was to ditch my 85ah (two years old now) and use the 110ah which is brand new, so thats the route i'll take.
     
  17. Bulletguy

    Bulletguy Read Only Funster

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    Always good to get other opinions.....even if they are not technically correct!
     
  18. Johno

    Johno Read Only Funster

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    Hi Bulletguy

    If you want info' on batteries try this site I can guarantee it will be technically correct
    Battery University.com .

    Regards John
     
  19. hilldweller

    hilldweller Funster Life Member

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    Fair enough.

    Out battery is the original, so nearly 6 years old now and still does 3 days at least.
     
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