Connecting backup batteries of differing capacity's





Results 1 to 8 of 8
  1. #1
    Join Date
    Nov 2013
    Location
    Alberton
    Age
    59
    Posts
    514

    Default Connecting backup batteries of differing capacity's

    Hi,

    Is there any efficient / effective way to use batteries on different Ah ratings in the same circuit.

    I have 6 ea 12V 60Ah batteries and 4 each 12V 100Ah batteries. Is there an effective method to connect these to make them usable with an inverter, be it 12, 24, 36 or 48V.

    The first problem I can see is the difference in the recommended / ideal charging and float currents for the two different batteries.


    Cheers
    Last edited by Andrew Leigh; 2019/11/14 at 02:40 PM.

  2. #2
    Join Date
    Aug 2007
    Location
    Carletonville
    Age
    53
    Posts
    6,592

    Default Re: Connecting backup batteries of differing capacity's

    Any batteries you connect in series, keep the same Ah together. You can take a fair chance stacking them a parallel.

    So you can use all your batteries in a 12 or 24v system, but you will have some left over, you can send to me, if you have a 36 or 48 system.

    The experts will be along soon and shoot my Hillbilly approach down, it has worked for me before though.
    David/Hillbilly - 1997 SFA Nissan Sani 2,7 TD - 5" lift on 33" tires - Dual Transfer with 4.1 gears

    http://www.youtube.com/user/davidabcab



  3. #3
    Join Date
    Oct 2011
    Location
    Midrand
    Age
    48
    Posts
    2,777

    Default Re: Connecting backup batteries of differing capacity's

    I have 150Ah 4x12V ->48V connected in parallel with 4 x 200Ah ->48V. Logic tells me that whichever bank pulls a lower voltage first will transfer the load to the higher voltage (200Ah in my case as they are newer) until that falls to the level of the lower bank and so it will go down until both banks are empty.

    I have not had any problems with my setup to date, but Fluffy will have more experience and probably wiser input.

  4. #4
    Join Date
    May 2009
    Location
    Hillcrest, Malaysia
    Age
    63
    Posts
    18,583

    Default Re: Connecting backup batteries of differing capacity's

    Quote Originally Posted by bfreesani View Post
    Any batteries you connect in series, keep the same Ah together. You can take a fair chance stacking them a parallel.

    So you can use all your batteries in a 12 or 24v system, but you will have some left over, you can send to me, if you have a 36 or 48 system.

    The experts will be along soon and shoot my Hillbilly approach down, it has worked for me before though.
    Spot on actually.

    If any batteries are in series they MUST be the same AH or very similar.

    Batteries in parallel, whether 12/24 or 48V series strings, can be a mix of AH. Batteries in parallel actually share quite nicely, both when charging and discharging.

    Just one thing - make sure all batteries are FULLY charged before connecting parallel strings. If the batteries ever get out of sync, separate them and charge each string independently, then put them back in parallel.
    Cheers

    ZS5KAD
    3 V8's
    NA TwinTurbo SuperCharger
    A V6 and an inline 4

    The frogs are starting to notice that the water is getting warm but it is already too hot to do anything about it.....

  5. #5
    Join Date
    Nov 2013
    Location
    Alberton
    Age
    59
    Posts
    514

    Default Re: Connecting backup batteries of differing capacity's

    Hi guys,

    So which of the following is more advisable?

    Click image for larger version. 

Name:	24V and 48V Setup.JPG 
Views:	143 
Size:	30.8 KB 
ID:	547882

    Cheers

  6. #6
    Join Date
    Jan 2013
    Location
    Friemersheim, Southern Cape
    Age
    57
    Posts
    3,892

    Default Re: Connecting backup batteries of differing capacity's

    Quote Originally Posted by Andrew Leigh View Post
    Hi guys,

    So which of the following is more advisable?



    Cheers
    Neither
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	IMG_5255.jpg 
Views:	61 
Size:	249.5 KB 
ID:	547913   Click image for larger version. 

Name:	IMG_5256.jpg 
Views:	63 
Size:	280.4 KB 
ID:	547914  
    1998 Daihatsu Rocky 'The Kitty'
    2002 Daihatsu Rocky 'The Bully'

  7. #7
    Join Date
    Nov 2013
    Location
    Alberton
    Age
    59
    Posts
    514

    Default Re: Connecting backup batteries of differing capacity's

    Thanks.

  8. #8

    Default Re: Connecting backup batteries of differing capacity's

    Quote Originally Posted by bfreesani View Post
    Any batteries you connect in series, keep the same Ah together. You can take a fair chance stacking them a parallel.

    So you can use all your batteries in a 12 or 24v system, but you will have some left over, you can send to me, if you have a 36 or 48 system.

    The experts will be along soon and shoot my Hillbilly approach down, it has worked for me before though.
    shoot my Hillbilly approach down .... spot on actually, why shoot it down ?
    The only thing wrong is you want the left over batteries, would do much better in my system

    On a serious note though, try not to put more than three sets in parallel, you start picking up problems with charging. The more series you have the better. The series string containing the lowest A/H battery will determine your A/H rating for that bank.

    Four Wheel Drive Club of SA
    Garden Route Division
    A Proud member of SCROF (Southern Cape Route Owners Forum) see our website at www.4x4ineden.co.za

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •