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Technical Is it ok to use 12volt battery in 6 volt system?

Discussion in 'The Hokey Ass Message Board' started by Wizard, May 25, 2020.

  1. squirrel
    Joined: Sep 23, 2004
    Posts: 46,374


    again, do NOT do this!
    olscrounger likes this.
  2. Boneyard51
    Joined: Dec 10, 2017
    Posts: 4,059


    When explaining electricity to people , I use water as a visual aid . Usually before I start my discussion, I tell people that , and explain that water behaves similar to electricity and in most cases it makes it easier to understand. But water is not electricity, so they are not exactly ,100% alike In their behavior .... only similar.

    VANDENPLAS likes this.
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 46,374


    the 12v vs 6v battery with the same size...and pressure vs flow rate as analogs for voltage and current...

    here's the example: Garden hose, connected to faucet, faucet turned on. Water comes out the hose, nice big flow, but it won't squirt very far. Put your finger over the end of the hose, and the pressure builds up, till you can't hold it completely over the end any more. Now the water is squirting real far, but not coming out the end of the hose as fast.

    The 12v battery has a higher "squirt", but less current "flow".

    If you can't understand that, then you probably can't understand electricity, and should quit asking questions.
    Thor1, olscrounger and VANDENPLAS like this.
  4. F-ONE
    Joined: Mar 27, 2008
    Posts: 2,248

    from Alabama

    12 volt battery in 6 volt car?
    Your amp gauge will live.
    The fuel gauge will go Yippy! and then roll over and float to the top of the bowl.
    The lights may work....for a while.
    Really all you need is 4 bulbs 2 heads and 2 tails. Oddly enough the 6v heads may last years.
    Who needs dash lights and for that matter a fuel gauge?
    Radio, it’ll be floating right beside the fuel gauge. Who listens to AM anyway?
    That fan will blow like the devil....for a little while.....maybe years.
    Buy points by the gross.
    The horn will blow...real loud.
    The starter will spin really fast.....for years to come.
    Keep a cool bottle of water handy to pour on that hot starter solenoid on those warm days.
    Many will say the 6 bolt generator will not charge a 12v battery.....
    Funny thing.....the battery never went dead.

    I had a 50 Ford Coupe that a previous owner converted to 12 volts.....
    He did it the simple way. He took the 6V battery out and put a 12V in.
    No dash lights, no fuel gauge.....those lasted about 10 seconds after the “conversion”.
    I wanted to drive it so I did. I put in a ballast resistor and honestly that was about it.
    I just drove locally expecting to charge the battery every so often. The battery never went down.

    Would I recommend such..... absolutely not!
    chopped likes this.
  5. The37Kid
    Joined: Apr 30, 2004
    Posts: 27,236


    Thank you Jim, I respect you for not adding simple to the description, and you are correct I'll die not understanding it.

    Thor1 likes this.
  6. alanp561
    Joined: Oct 1, 2017
    Posts: 1,100


    I LOVE THIS PLACE. It's stuff like this that keeps my heart pumping.

    Sent from my SAMSUNG-SM-G891A using The H.A.M.B. mobile app
    nochop likes this.

  7. :p:p:p

  8. Truck64
    Joined: Oct 18, 2015
    Posts: 4,075

    from Ioway

    The 6 volt battery has 3 cells. The 12 volt battery has 6 cells. A battery is a collection of cells connected together. In this case in series, so the voltage of each cell is additive. When connected in parallel the voltage stays the same but the current capacity is doubled.

    Army trucks used four (4) large 12 volt batteries connected together in a series-parallel arrangement to make one big ass starting battery at 24 volts and a gazillion amperes.
    pitman and VANDENPLAS like this.
  9. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 258

    Alliance Vendor

    There is something wrong with that explanation.
    The components on a car require a certain amount of POWER to operate. Volts X Amps = POWER or WATTS ((simplified for this discussion)).
    If a head light requires 60 VoltAmps to illuminate the road, that is the amount of power required.
    That power can be obtained by 6 volts and 10 amps (60 VoltAmps) or by 12 volts and 5 amps (60 VoltAmps).
    12 volts don't "put out" 1/2 the amps, it's the component that requires 1/2 the amps on 12v as it does on 6 volts.

    12 volts can use smaller wires since the component requires half the current with the same VoltAmp power as 6 volts. To use the water analogy, 1/2 the water flow requires a smaller hose.
    Last edited: May 26, 2020
    VANDENPLAS likes this.
  10. mickeyc
    Joined: Jul 8, 2008
    Posts: 1,063


    If you can get a copy of the "Official 12-Volt Conversion Guide" Written by Randy Rundle
    you should find it helpful. Quote " a step by step guide to everything you need to know about upgrading
    a 6-volt system to 12-volt." printed in 2008. I have seen
    the book offered in various places. I think Bob Drake and Dennis Carpenter offered it at much inflated prices. I bought my copy for ten bucks which was the
    authors original price. If you do a search I would think
    you could find a copy. I like it.
    pitman and nochop like this.
  11. nochop
    Joined: Nov 13, 2005
    Posts: 1,641

    from norcal

    Not gonna, just curious, thanks if I was a cat I would still be alive
  12. One problem with 6V batteries is they're not made in all the sizes they used to be. 'Back in the day' if you needed something odd-ball you could go to a battery shop and they'd build you one. I don't know if any of these shops still exist, but it might be worth checking into. If you find one, tell them you need a heavy-duty version.
  13. leon bee
    Joined: Mar 15, 2017
    Posts: 499

    leon bee
    from Arkansas!

    I carelessly hooked my 12 volt Battery Tender Junior, (looks just about like my 6v one) to a newish 6 volt Optima and went off and left it for a couple days. Come back; Oh Shit! hadn't done anything at all, Battery Tenders are smarter than me.

    Edit to add: That 6v Optima cost me 187 bucks 3 years ago. It holds 6.3 volts for weeks unless I run it down messing with something, and it spins my flatheads fast.
  14. pitman
    Joined: May 14, 2006
    Posts: 4,933


    That there'a whole lot of Coulombs running amuck! :eek:
    (Coulomb per sec. = Amp)
    Truck64 likes this.
  15. Terrible80
    Joined: Oct 1, 2010
    Posts: 772


    The only thing confusing about the water/ electricity anology is a closed switch = an open valve. Lol

    Sent from my LG-TP450 using The H.A.M.B. mobile app
    olscrounger likes this.
  16. 5window
    Joined: Jan 29, 2005
    Posts: 7,458


    Yes, I wrote it wrong and will need to fix it. Larger diameter wire has less resistance so 2 gauge will pass more current than 4 given the same voltage.
    Last edited: May 26, 2020
    olscrounger likes this.
  17. 5window
    Joined: Jan 29, 2005
    Posts: 7,458


    Four twelve volt batteries, hooked together in series wiring, give you 48 volts.
  18. 5window
    Joined: Jan 29, 2005
    Posts: 7,458


    There is probably no such thing as too big a wire. Too small a wire and increased resistance means increased heat
    VANDENPLAS likes this.
  19. ok, so lets start the question all over....
    The original poster did ask questions I am still curious about.
    Start at ZERO volts,
    then charge only to 6 volts, whatever base battery you choose.
    following so far?
    You will NOT have 12v surges or 12v burnouts guaranteed, so drop those from the stories.
    There was never 12 from the start. never.
    Can a 12v battery be a reasonable base to use for charging to only 6 v for a 6v life?
    Can a "12v" battery only be charge to SIX ?
    or will it have a shorter life from not being fully utilized?
    Do not assume a 12v initial charge. That didnt happen.
    Do not assume 12v anywhere.
    Can a "12v" battery BASE be charged to 6v and still have a useful life?
    I do not understand how a simple question can have so many higher voltage assumptions added to the simple question of 6v charging and 6v use.
    Can a x volt battery accept a 6v life if it is charged only to 6v?
    Will living life as a 6v, kill a FORMER 12v battery, or can it live a reasonable life as a "6v"?
    Please do not inject 12v where 12v was never used.
    Can a battery built to accomodate a "higher voltage" be used as a battery with lower voltage charging and lower voltage use if it is charged at a voltage less than its rated max??

    Ok, lets assume a formerly 15v bat charged to 8 or 9 ....

    If you let a 12v battery discharge to 3 or 4 volts , then charge it up to 6, then use it at 6 , are you killing it, or can it survive on 6 for a reasonable time ?

    I guess it can also be stated as - can you charge and run a battery at lower than its original designed voltage, and still get a reasonable life at the lower voltage?
    Can a battery be charged to half its rated capacity and still have a decent life?

    Last edited: May 26, 2020
  20. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 534

    from 94577

    Wow, this got going in not quite the direction I thought it would.

    Using your example above, we have two same size batteries, yet two different voltage ratings.
    To understand this better you have to know how a battery is constructed.
    Let's start with a 12V@750CA battery.

    With a typical 12V wet cell lead acid battery, if you were to remove the top you would see six individual chambers each having what looks like plates sitting in the acid solution.
    Each individual cell can produce 2.1 Volts. Because in reality a '12V' battery(fully charged) is 12.6V
    There are six cells connected in series.
    Connect those six cells together in same polarity series + to - the cumulative effect of these cells adding together creates the total battery output of 12.6Volts.
    With a typical 12V wet cell automotive battery, 6(cells) X 2.1(Volts) = 12.6 Volts
    Amperage of each cell is 750A, but ampacity does not increase with series connections so total battery CA output is still only 750A

    Again we take the same six 2.1Volt cells, in the same case, same acid solution. However we connect the cells together just a bit differently.
    We pair up the cells, so rather than having six cells in series, we are going to have three pairs of cells connected in parallel + to + and - to -. This does not increase the paired cells voltage, but it does increase it's ampacity. Now we have three pairs of 2.1Volts cells @1500CA.
    We now connect those three paralleled connected cells in series + to -.
    3(paired cells) x 2.1 = 6.3Volts.
    We now have a 6.3V 1500CA battery.

    So although ye olde law of physics states we can't get anything for free, we also don't give up anything for free.
    12.6V X 750CA = 9450Watts
    6.3V x 1500CA = 9450Watts

    Normally a 6V battery only has three cells and ~750CA, only reason we have the added ampacity is to use all parts in your designated example.
    Now if you have found two same sized different voltage batteries that had similar amp or amp/hour ratings, then something fucky is going on.
    pitman and 5window like this.
  21. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 534

    from 94577

    Not without physically changing the internal components around to make a 12V battery into 6V. Or if you could it probably would have crappy ampacity, which would render it pretty useless for starting.
    A battery is built to be a given voltage. You cannot just 'half charge' the battery and expect it to run as a normal battery. It might work for a bit but I can't see it reliably working for extended periods.
    If we could I'm sure big batt would find a way to prevent it. :D
    pitman and 5window like this.
  22. an answer!
    Thank you much! :)
    I get it now

  23. 5window
    Joined: Jan 29, 2005
    Posts: 7,458


    Back to basics. There's no reason your 6V should fail faster than a 12V. Read MadMikes construction post. So-do you have a bad battery? Do yo have a good trickle charger? Have you checked your charging system-regulator, open ground, working alternator/generator? Something is making that battery drain. Don't just through batteries at it-get it fully diagnosed.
  24. Truck64
    Joined: Oct 18, 2015
    Posts: 4,075

    from Ioway

    Correct. The Army trucks used two sets of series wired 12 volt batteries connected in parallel.
  25. Truck64
    Joined: Oct 18, 2015
    Posts: 4,075

    from Ioway

    I don't believe so. It has to do with each individual cell, that has a specific gravity and voltage. A battery "likes" to be fully charged, that is each cell within the battery is all plussed up or topped off. If it isn't, bad things start to happen.

    Remember a "12 volt" starting battery battery is almost completely dead at a measured 12 volts, and anytime discharged below about 11 volts may be permanently damaged and underviceable. It won't happen every time, but it should be checked.

    A 6 volt battery is just "half" of a 12 volt battery. Half the number of cells. If every cell within any battery is only half charged, it is only half charged, and they don't like that, no matter how many are stacked up.

    It will work temporarily if I had to guess, but only for a very short time. Starter current is pretty stout. One of the individual cells would likely hork out, maybe go into "reverse voltage". At best, if it does work it would permanently sulfate the plates and be completely ruined in a few months.

    Why don't you buy a 12 volt battery and try this? Increase the horde HAMB learnin' and lay some knowledge on us.
    VANDENPLAS likes this.
  26. patsurf
    Joined: Jan 18, 2018
    Posts: 385


    this is not a reply ONLY to this last post-but...even squirrel has given up on this-lets let it die!-there's always an auto electric shop around for the people who need one!!-this has run the same course as when people get the engine out of ignition timing...
    redo32, VANDENPLAS and Truck64 like this.
  27. jaracer
    Joined: Oct 4, 2008
    Posts: 376


    It has to do with the amount of power required. It takes the same amount of power to run the starter motor whether you use 6 or 12 volts. The electric term for power is Watts. Watts is calculated by multiplying amps X volts. Let's say the power required to operate a starter motor is 1200 watts. If you operate the starter with 6 volts the starter would draw 200 amps. If you operate it with 12 volts, it would draw 100 amps to do the same amount of work (starting the engine). The more amps a device draws, the larger the wire gauge required to accommodate the amperage. Going from 6 to 12 volts allowed the manufacturers to use smaller gauge wiring.
  28. racerlall
    Joined: Mar 18, 2011
    Posts: 92

    from WA

    now how about lithium ion battery
  29. jaracer
    Joined: Oct 4, 2008
    Posts: 376


    The previous owner may have had someone adjust the voltage regulator. I'm guessing a 6 volt generator could live a while since most of the accessories were burned out. We used to put 8 volt batteries in Olds and Caddy's, it just took setting up the regulator to about 9.5 volts.
  30. Truck64
    Joined: Oct 18, 2015
    Posts: 4,075

    from Ioway

    So um, ported or manifold for distributor connection?

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