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8 volt battery in a 6 volt system

Discussion in 'The Hokey Ass Message Board' started by jhaas63, May 12, 2013.

  1. jhaas63
    Joined: Jan 15, 2013
    Posts: 136


    I am using an 8 volt battery in my 6 volt positive ground stock set up. The battery was dead after a bunch of driving when I stopped to get fuel. I read on another forum that the voltage regulator needs to be set at 9 volts to charge the 8 volt battery. Is this true?

    This is for a 53 ford f100 with the 239 flathead.

    Thanks for the information.
  2. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,164

    Atwater Mike

    If your generator/regulator are working at all, the battery should not have gone dead while driving!
    Do the arithmetic...
  3. My dad had an 8 volt battery in his '55 Chrysler & I don't know for sure but I don't think he did anything but put the battery in it....
  4. Yes, How do you expect to keep a 8 volt battery at 8 volts if it only charges at 6.....

    think about it....
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  5. lht
    Joined: Jan 18, 2013
    Posts: 243


    8 volt battery thats new to me i don't doubt it nothing electrical suprises me
  6. A 6 volt battery wont charge at 6.
  7. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,164

    Atwater Mike

    8 volt batteries have been around for a 'looong distance'.
  8. Diavolo
    Joined: Apr 1, 2009
    Posts: 810


    First... why?

    Second. Yes, your battery has to be charged with a voltage higher than the rated voltage for the battery. 12V needs 8V needs at least 9, 6V needs at least 7.5 and 12V needs at least 13.5.

    If you are running a 6V system and using an 8V battery, you are overtaxing your electrical components. Lights will burn out quicker, etc. Either stay 6V, upgrade EVERYTHING to 8V, or just go 12V.

    Based on your vehicle, I can't see why you wouldn't just go 12V and have the reliability of a 12V system, the ability to get a jump (or help a fellow motorist and jump them) easier starts, brighter lights, etc. The conversion to 12V is cheaper than converting to 8V in my opinion and you will have a better system.
  9. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,253

    Rusty O'Toole

    A fully charged wet cell is 2.2 volts. This means your fully charged 6V is 6.6, 8V is 8.8, 12V is 13.2.

    Plus you must have a higher potential at the generator to get the current to flow into the battery. So a 6V reg is usually set to about 7.2, an 8V 9.4 and a 12V 14.5.

    So, if you put an8V battery in you need to adjust the voltage regulator.

    This is an old cure for a weak electrical system. These days it is far easier and better to use an Optima style battery. They are way better than the old lead box. Or, use a conventional battery, it will work fine if the electrical system is in good shape, and you drive the car once in a while, or use a battery tender.
  10. Roger Walling
    Joined: Sep 26, 2010
    Posts: 1,144

    Roger Walling

    I have a 8v batt in my 6v 55 Chrysler. I wanted to use the old radio and generator (with the P/S pump). so I diden't go for the 12volts. WRONG! Have you ever listened to what is on an AM radio?

    Another problem is the cost. $130 for the Batt. and another $125 for a Petronics 8v system. Next time that I have to buy a batt., I will switch to 12v. and use a 56 Chrysler generator. (and but a F/M radio/ CD)
  11. How do you charge an 8V battery on a charger? Mine only has 6/12V ratings.
  12. Mr48chev
    Joined: Dec 28, 2007
    Posts: 27,176


    An 8 volt battery in a six volt system is an old shadetree fix for cars that were hard to start and probably more popular in cold weather areas but the regulator does have to be cranked up and other electrical components suffer the consequences in the process. Head lights and other light bulbs don't last as long and usually the generators crap out a lot earlier as they are working beyond their normal range. One of the things I picked up from my former stepfather and his cronies back in the late 50's.
  13. 1941coupe
    Joined: Jul 4, 2010
    Posts: 397


    I just converted my 41 with a 1950 merc engine to 12 v best single improvement you can do.
  14. Hefty Lefty
    Joined: Apr 30, 2013
    Posts: 170

    Hefty Lefty

    8 volt has its pluses and minuses, no pun intended.

    Lights are very bright, but do not last as long. Starter cranks real well. Ignition gives plenty of zap.

    The voltage regulator needs resetting or replacing with a solid state DIY or after market one. I don't think it is too hard on the generator, but there were 8 volt field coils for them back in the day.

    Plays hob with a tube radio as the filaments glow too brightly, but it would be possible to use dropping resistors. Each tube will need its own which will have to be determined on a bench with a power supply. The vibrator supply will find it harsh too but do what I came up with and friends did, buy a Vicor switch mode brick 5-10 volt to 250 or 300 volt supply. Surplus places have them cheap on occasion.

    8 volt is a TRADITIONAL HOT ROD deal if ever there was one. Looks cool. That counts for something.
  15. Hefty Lefty
    Joined: Apr 30, 2013
    Posts: 170

    Hefty Lefty

    Many tractors were factory 8 volt. There were 8 volt light bulbs but farmers liked the brighter headlight and it usually failed early from vibration anyway.
  16. 42merc
    Joined: Dec 19, 2010
    Posts: 718


    8 volt batteries were common crutches on worn 6 volt Olds V8's. Set the voltage regulator up to charge the 8 volt & things worked quite well. Headlamps that were rated at 6 volt only would burn out more often, the other bulbs were rated at 6-8 volts and rarely failed. Burned out bulbs were a small price to pay once you stalled a 6 volt Olds at an intersection and it wouldn't start again until it cooled somewhat.
  17. ckunsman89
    Joined: Feb 9, 2010
    Posts: 96

    from cocoa, FL.

    Just set your regulator to 9 volts and carry on. I did the same thing on a 51 chevy to help ease of starting and never had a problem. That truck had no radio, so I have no comment there, but the lights never burned out on me, and I never had a charging problem.
  18. my 2n tractor likes that extra current......
  19. F&J
    Joined: Apr 5, 2007
    Posts: 13,214


    My son inherited his grandfathers 51 8N that he bought new. It has had a 8v since the 60s.. "When you go to use the tractor at zero or 10 degress below, it needs to start"...that's his words when he still used it
  20. Bryan G
    Joined: Mar 15, 2011
    Posts: 176

    Bryan G
    from Delmarva

    If everything is fixed right, 6 volts is all you'll ever need. Anything more is just a band aid for some overlooked problem.
  21. Yes, true. I didn't want to confuse the matter.
  22. G-son
    Joined: Dec 19, 2012
    Posts: 637

    from Sweden

    Get some rectifier diodes large enough to handle the current draw of the radio, lamp or whatever. Put two of the diodes in series on the supply wire to the radio/lamp/etc. Rectifier diodes has a forward voltage drop around 1V (varies a little with temperature, type and how much current goes through it), so two in series will kill off about 2V and your radio etc. will be thinking it is still connected to a standard 6V system.
    If you want a brighter lights than on 6V but not kill them as quickly as when connevted straight to a 8V system, use only one diode to reduce the voltage 1V, not 2V.
  23. Magnum Wheel Man
    Joined: May 11, 2011
    Posts: 418

    Magnum Wheel Man

    because my 38 Nash had someone who previously put the smaller gage 12 volt cables on the car before I bought it, & it started hard, & needed a new battery, I bought an 8 volt... it's been in the car for going on 3 years now... however mine has a "cut out" prior to a "real" voltage regulator... my headlights were also previously switched to 6 volt sealed beam, & I've since replaced them with 12 volt bulbs( as all the headlights & taillights burned out within the 1st year of adding the 8 volt battery )... they are probably about the same brightness as the original 6 volt bulbs with a 6 volt battery... my cut out easily keeps my battery charged, & is in fact a little hard on water...

    my car starts great, but if I had to do it again, I would have just put the heavier cables on, & kept it 6 volt... now I'm thinking of converting to 12 volts, & replacing my gauges, lights are already replaced... also thinking about buying a 6 volt positive ground alternator to replace my generator & cut out for a single wire alternator, only would require some mods, as my generator drives my water pump, but I have a welding / machining fabricator buddy that could modify the alternator so it could still drive the water pump...
  24. 56FRLN
    Joined: Feb 7, 2012
    Posts: 221


    We put an 8 volt battery in a '52 Chevy farm truck in my younger years as a fix to hard starting on cold winter mornings. The truck did not have a radio but I don't remember ever having to replace light bulbs and we ran it that way for years. We had them in both tractors also for the same reason.

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