Batteries again (sorry)

Discussion in 'Tech/Mech General' started by knokinonabit, Feb 24, 2012.

  1. knokinonabit

    knokinonabit Funster

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    I am almost certain someone will have asked this before, but I have searched and can't find it. So here goes.

    On our Elddis 155 there is only one leisure battery and it is a paltry 75 amps, not going to last long, I fear. I am going to fit a second battery in parallel and would like to know if I have to fit another 75 amp one or can I link in a 110 amp battery, for instance.

    If I have to fit two the same there may well be a new (ish) 75 amp battery for sale.

    I'm sure I will get some p**s taking for asking, but I'm married and used to it. Thank you all in anticipation. :thumb:
     
  2. JJ

    JJ Funster

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    I believe the perceived wisdom will mean you have a battery for sale...

    It is generally advised to only join two like batteries together (size and age)

    JJ :Cool:
     
  3. knokinonabit

    knokinonabit Funster

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    Bu**er, I knew that would happen :BigGrin:

    Thanks JJ
     
  4. Geo

    Geo Trader - Funster

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    Been asked many times but never let that stop anyone from asking
    Best practice/puritan answer is two new batteries of the same size
    Your new 110 if fitted with a 75amp may not get properly charged as the charger may see the 75 amp full and cut out at that
    110+75 = 185 divide by 2 = theoretical 92.5 amp performance at best
    Real world you can connect whatever yo want and it will work with limitations such as above
    Geo
     
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  5. knokinonabit

    knokinonabit Funster

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    Thank you Geo.

    That makes sense to me so two new batteries it is then.
    Hang the expense :cry:
     
  6. pappajohn

    pappajohn Funster Life Member

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    still having a problem with this theory....your charger doesn't know you have two (or more) batteries fitted or what capacity they are and only see's one 12v 185ah battery so will put in 185amps in a given time.

    connected in series(24v charger) it should only charge to the average of the two different capacity.

    110ah plus 75ah = average capacity of 92.5ah
     
    Last edited: Feb 24, 2012
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  7. Reallyretired

    Reallyretired Funster

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    True to a point but not a 24v charger for 12v batteries please :Doh:
     
  8. pappajohn

    pappajohn Funster Life Member

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    Ooops....meant series :Doh:
     
  9. spannermanwigan

    spannermanwigan Read Only Funster

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    I added a 95 amp to our original 75 amp, everything working fine
    just gave us a lot more peace of mind when away as we dont normally
    use sites but move daily or at most 2 days as we find this suits us best.
    Will however fit 2 the same when these go.

    Regards
    Steve:thumb:
     
  10. jubilado

    jubilado Read Only Funster

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  11. jonandshell

    jonandshell Funster

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    Have you got the standard Elddis thetford-type external battery door with the integral hook up lead socket? Our old Elddis had one of those. Just check with a tape measure to be sure before ordering a battery though!

    If so, a single 'Dyno 30HH' 115 ah traction battery should squeeze in and outperform anything you can buy with 'leisure' on the side of it!

    £125 should get you one, delivered.:thumb:

    http://justcarbatteries.co.uk/index...t-batteries/dyno-30hh-industrial-battery.html

    there is also a 130ah with the same dimensions-

    http://justcarbatteries.co.uk/index...-batteries/dyno-30xhs-industrial-battery.html

    All good manly batteries for an ex-wedge like yourself!

    PS, connect whatever you like in parallel, the old wive's tale about both your batteries only getting the charge of the smallest only applies to batteries or cells in series!
     
    Last edited: Feb 24, 2012
  12. pappajohn

    pappajohn Funster Life Member

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    :thumb:
     
  13. JJ

    JJ Funster

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    Quote...

    "I believe the perceived wisdom will mean you have a battery for sale...

    It is generally advised to only join two like batteries together (size and age)"


    Please note I used political language with words like [HI]"believe"[/HI] and [HI]"perceived wisdom"[/HI] and [HI]"it is generally advised"[/HI]...

    This is what seems to be the majority view on this forum...

    As for me... well... in the past I have fitted new(er) batteries in parallel with old ones and different amperage ones together... I don't know if one "dragged the other down" or whether the "charger got confused" or not. I've always found two (working) batteries to be better than one and three (working) batteries to better than two...

    ...but never blindly do what I do... that is only for me...:Wink:

    If the lights go on when I switch the switch and the laptop and/or phone charges up ok then all is well with my electric world...:Rofl1:

    JJ :Cool:

     
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  14. normanandsue

    normanandsue Funster

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    At the risk of completing the cycle of seemingly silly battery questions; I have only one leisure battery if I want to fit another do I just connect the + terminals together and the - terminals.
    Surely it cant be that easy - if so I can do this.

    Norman
     
  15. Madmark62

    Madmark62 Read Only Funster

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    Yes basically it is that easy. Then take the positive lead from one battery and the negative lead from the other, that way both batteries are used together and neither one is getting more draw from it.
    That is what I was told and it has worked ok for me on the boat, but I have 6 batteries joined together.
     
  16. TheBig1

    TheBig1 Funster Life Member

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    Yes, but place them as close together as is practical. Use heavy guage wire and ALWAYS put a minimum of 1 fuse in the +ve joining cable. If the cable is over 30cm, it is good practice to fuse at each end. This way if one battery fails and goes short circuit, or the cable gets damaged the fuse/s will blow protecting the other battery and your vehicle.

    There is nothing stopping people mixing and matching sizes of battery, but it is generally unwise to add a new battery to one reaching the end of its expected life. Batterys are only good for a limited number of recharge cycles, as the plates that make them work collect sulphate each time they charge reducing its capacity. This means the difference in charging rates can be higher than 2 matched batteries, so killing the old one off quicker. Modern van chargers will supply 25+ amps at 13.8v on demand to a low battery and just a trickle charge to one that is near or at capacity. If linked, an old battery will reach its full state before the new one, so will continue receiving a high amp charge potentially boiling off electrolyte and creating explosive hydrogen gas
     
  17. geoff1947

    geoff1947 Read Only Funster

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    battery

    I know the question is about TWO bty's but for info I am purchasing an Elecsol 110amp bty from eddievanbitz who is a member of Fun and he offers 15% discount for us paid up members He has a site at Shoreditch Taunton and tel no is 01832 21992 so if your passing etc:Eeek:
     
  18. Reallyretired

    Reallyretired Funster

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    Connection is as said + to + and - to -. Make sure your fuses are suitably rated to protect the wiring and make sure they are rated high enough for your likely load. Theoretically the fuses between the batteries only need to be rated above half the maximum load (with two batteries) but if you put 30A fuses between them and try to run a 15Kw inverter you will blow the fuses between the batteries, and may not even notice that it is only running off one battery. Mine uses very thick cables and is fused at 300A. You can get these fuses at car audio places as they are used by those dreadful thumping music systems the yoof of today like. Maplins does 4WG cables at a surprisingly reasonable price.:thumb:
     
  19. knokinonabit

    knokinonabit Funster

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    That is exactly the type that I have. My main concern was space for two batteries so I was going to extend under the "lounge" seat that the original battery housing is in. I will probably fit a larger battery in the original housing and re-mount the existing battery as it will take up less space.

    Thank you for that advice.

    Thanks to everyone who took the time to post replies. :thumb:
     
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