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Connecting Two Batteries together

Discussion in 'The Hokey Ass Message Board' started by grits, Mar 1, 2011.

  1. Gahrajmahal
    Joined: Oct 14, 2008
    Posts: 493

    Gahrajmahal
    Member

    The 1970 MGB I recently acquired has two small wells just behind the seats for two six volt batteries and a 12 volt system. I suppose back then 12 volt batteries couldn't be that small. It now has a single 12 volt that fits in a single well. It is 7 years old I am told, and still cranks it over just fine.
     
  2. I realize the cost envolved with the 2 batteries, it was just thinking in and out of the box to use the space I have the best way possible, honestly, the only thing that I would ever use the trunk for is just a small tool pack or something like that, but thanks for all the input, I really appreciate it.

    That's what to me is the best about this place, ask a question and within minutes you have all the answers you need.
    Have a great day everyone.
    Vival La H.A.M.B.
     
  3. 53sled
    Joined: Jul 5, 2005
    Posts: 5,817

    53sled
    Member
    from KCMO

  4. George/Maine
    Joined: Jan 6, 2011
    Posts: 949

    George/Maine
    Member

    Oh let add to the bull.Back in the day when 12 volts was un heard of,when a 6 volt car didn,t turn over fast enought you could take 2 6s in series get it going that way.The way batterys are made they are joined together + -+- , so +-+- is 12 volts
     
  5. Pete1930
    Joined: May 5, 2006
    Posts: 321

    Pete1930
    Member
    from Boston

    MG used (2) 6-volt batteries in the MGB up to, I think, 1974. Car was still 12V negative ground.

    Pete
     
  6. junk yard kid
    Joined: Nov 11, 2007
    Posts: 2,718

    junk yard kid
    Member

    This is very common in motor homes. You have to make sure the batteries are the same size, quality, age, rating, and charge otherwise one will drain into the other one and eventually they will just both go dead.
     
  7. shoprat
    Joined: Dec 23, 2006
    Posts: 1,109

    shoprat
    Member Emeritus
    from Orange, CA

    Did it a boat. Worked great. We sure get a lot of folks answering questions
    on here that don't know the answers:confused:
     
  8. zibo
    Joined: Mar 17, 2002
    Posts: 2,361

    zibo
    Member
    from dago ca

    If you put batteries in a long flashlight,
    they all go in + to -,
    and only use the first and last +/- contacts
    which basically adds up all the voltage.

    Old Morgans used 2 6-volt batteries to make up 12 volts.

    TP
     
  9. zibo
    Joined: Mar 17, 2002
    Posts: 2,361

    zibo
    Member
    from dago ca

    Oh yeah,
    I'm running a 6volt system,
    and just have an extra battery in case the generator dies.
    However,
    I can double them up to 12v in the future.
    [​IMG]

    TP
     
  10. smiffy6four
    Joined: Apr 12, 2010
    Posts: 333

    smiffy6four
    Member

    Sorry dude, but 2x 6 volts in series =12v

    If they were connected in parallel, then you would have 6v.
     
  11. CGkidd
    Joined: Mar 2, 2002
    Posts: 2,908

    CGkidd
    Member

    A saying I learned from a crusty Senior Chief electrician when I first got out of EM school in the CG. Save Pay = Series adds voltage and Parallel adds amps I am actually going to go with the same set up of two 6volt optima's under the bed of my project in series.
     
  12. MGA's from the late 50's came that way from the factory (space reasons behind the seat). Two 6 volts wired in series = 12 volts.
     
  13. nolly
    Joined: May 14, 2007
    Posts: 225

    nolly
    Member

    Here's George Poteets 32 Delivery with 2-6v batteries!
    [​IMG]
     
  14. Dale Fairfax
    Joined: Jan 10, 2006
    Posts: 2,585

    Dale Fairfax
    Member Emeritus

    One thing not touched on here(maybe irrelevant) is the old "Orpin" switch sold by J.C Whitney, It was a system that (when wired correctly) connected two 6 volt batteries in series for cranking (switch was energized by starter button) but reverted to parallel as soon as you released the starter button. Crank with 12-run on 6. Had one in my F-100 for years.
     
  15. terrarodder
    Joined: Sep 9, 2005
    Posts: 1,101

    terrarodder
    Member
    from EASTERN PA

    Did this back in the 50s, my budy had a 40 Ford with a hemi that started hard. Hooked two 6 volt battrys in series to starter, one 6 V. to the lights the the other one for ign., a wire from the gen. to each of them to keep the charge up.
     
  16. Jeff J
    Joined: Mar 15, 2007
    Posts: 961

    Jeff J
    Member

    I've ran those in 6 of my 32 roadster's that I've built . Put them on there side in the trunk area between the outside metal and the lid above the tank then covererd with a panel . to hide them . Used the Gel Batterys red top ones !
     
  17. 40FordGuy
    Joined: Mar 24, 2008
    Posts: 2,907

    40FordGuy
    Member

    Using 2 6v batteries was the way GM built some early 50's 12 volt Cadillacs...They had a long, narrow 6 volt battery in each front fenderwell, just ahead of the firewall. Yes, a real PIA to get to ! Two of our customers had them.

    4TTRUK
     
  18. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856

    Mike51Merc
    Member

    You know those caps on the top of batterys where we used to put water in? Well each of those caps represents a battery that puts out about 2.2 volts and they're all internally connected (in series) inside the case.

    Three caps = 6 volt battery
    Four caps = 8 volt battery
    Six caps = 12 volt battery
    and so on.

    You can add batteries in series to add up the voltages, or you can add them in parallel to add up the current (amps).
     
  19. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    Dang, Mike, ya beat me to that one!
     
  20. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    They cannot both be cumulative. In series, (+) of one hooked to (-) of the other is cumulative. (+) to (+) and (-) to (-) remains 6 volts but gives more amperage.
     
  21. aaggie
    Joined: Nov 21, 2009
    Posts: 2,530

    aaggie
    Member

    A little off topic but the 1960 MGA I used to have had two 6 volt batteries from the factory. There was a battery box in the floor behind the seats with one battery in each and the connecting cables run under the carpet to connect them.

    The Brits had a unique take on all things electrical.
     
  22. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 6,250

    Ebbsspeed
    ALLIANCE MEMBER

    More amperage and cumulative current are the same thing, aren't they? That's what he said.

    See post #42 above......
     
  23. Atwater Mike
    Joined: May 31, 2002
    Posts: 11,625

    Atwater Mike
    Member

    Back in the day...Love that one. My son's 1925 Dodge Bros. Coupe came from the Dodge factory with 12 volts!
    12 volt systems have been around since before then. Do a google search.
     
  24. Atwater Mike
    Joined: May 31, 2002
    Posts: 11,625

    Atwater Mike
    Member

    Not irrelevant at all, just a great post script. With that switch, you could get a 12 volt hot start and when switched back to parallel you charged both batteries with a 6 volt generator!

    Nice addition, Dale.
     
  25. davey
    Joined: Feb 10, 2007
    Posts: 62

    davey
    Member

    My motor home has 2, count them 2, 6 volt batteries wired positive to negative making `12 volts to the house
     
  26. No. Early 50s Cads were 6 volt and used one BCI Group 2, long skinny, battery
     
  27. rainhater1
    Joined: Oct 5, 2009
    Posts: 1,147

    rainhater1
    BANNED
    from az

    Three pages to say the same thing?
     
  28. woodypecker
    Joined: Jan 23, 2011
    Posts: 300

    woodypecker
    Member

    If you need a cheap small battery that will work get one of those cheap jump start battery packs take it apart and there is one of those expensive glass mat batteries inside.
     
  29. djust
    Joined: May 31, 2006
    Posts: 1,230

    djust
    Member
    from Oklahoma

    I think I am going to go that same route Grits.
    I want to put 2 6 volt batteries in series under my sedan to get more clearance, the 12 volt one I have now is just to big.

    Hell I'v got close to a 1000 batteries that I take care of and have several strings of 40 12 volt batteries wired in series to make up 480 volts and some strings that have 60 8 volt batteries to make 480 volts and one that has 80 6 volt batteries that make up 480 volts but the beauty of the optimas is that when laid on there side like pics above there is a ton of room saved.

    Not a lot of room in an A to start with.
     
  30. sunbeam
    Joined: Oct 22, 2010
    Posts: 6,213

    sunbeam
    Member

    One advantage of 2 sixes in series if you have a car that was 6v to start with you can tap into the cable between the 2 and run the 6v accessories.
     

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