Using an 8V Battery in a 6V Car — Why Not To Do It

Unknown
Unknown
edited November -1 in HUDSON
"...A slightly less high voltage approach is installing an 8 volt battery for just a bit more "oomph" when starting. But this leads to a new set of problems. To charge the 8V battery, your generator will be putting out 9.6V, so you will have to adjust the CO and VR settings in your voltage regulator (if you don't, the battery will discharge rapidly). Since wattage is a function of voltage squared divided by resistance, the 8V battery will be delivering nearly double the wattage (9.6V squared = 92 watts) of the stock 6V battery (7.2V squared = 53 watts).



All the bulbs in your car will be operating at a significantly higher voltage than they were not designed for (ever try to find 8V bulbs?) and they will burn out much more quickly, while 12V bulbs will be too dim.



If you drive much at night, the first bulbs to go are often the headlights...."



I find this very interesting reading:



http://www.356registry.org/Tech/battery_8v_in_6v_car.html



Those who have used the 8V batteries in Hudson's, have you experienced the negative sides too?

Comments

  • Jon B
    Jon B Administrator
    I can't offer any evidence pro or con, on whether 8 volts is good. But I can tell you that, in my pre-War Hudson at least, 6 volts works just fine. The starter turns over speedily and the car always 'catches', hot or cold, unless it's been sitting for a few days. (In that case the gasoline has generally evaporated from the carburetor and it takes maybe 10 seconds of cranking to pump additional gas into it.)



    The biggest problem with 6 volts is that it's not as forgiving of bad connections, as 12 volts is. Therefore, be sure you have the correct (thicker) 6-volt cable size, adequate grounding (engine to body, body to battery) and that all connections are 'bright and tight'. Of course, the battery should be of sufficient quality (mine has 780 cold cranking amps) and of course the starter and generator should be working correctly (if you've never had them checked, do so.)



    In my opinion most people using their Hudsons for non-daily use would be perfectly happy with keeping their systems 6-volt, if everything is running correctly. If you drive your car on a more regular basis, and/or you have a lot of modern accessories like AC or a CD player, well, that may be another matter...
  • Unknown
    Unknown
    The only reason to use an 8 volt battery is so the car owner doesn't want to fix the original problem(s). It's hard on the whole electrical system and causes more problems later on. Most of the time the problem is bad grounds and a worn starter. Remove all ground straps, clean to bare metal and re-attach. Make sure the gruond straps tie the grounded side of the battery, the frame, the body shell, and the engine together. Motor mounts are pretty good electrical insulators. I've seen cars that kept burning the speedo cables up because that was the only path to ground. Remember, these cars operated fine on 6 volts for years, and don't forget to use 6 volt cables!
  • PAULARGETYPE
    PAULARGETYPE Senior Contributor
    Right On Steve!!!!

    Bad Wiring Is The Cause And Masking It With A Quick Fix Is Not The Route To Go If Your Planning On Keeping The Car Now With That Said Some Other Conns The 8 Volt Batterys Don't Seam To Hold Up As Long As A 6 Volt



    I Have A Good Friend Who Said His Car Needed A 8 Volt To Start His Engine And Have The Car Run When We Checked At The Od Selnoid He Had 4 1/2 Volts With A 8 Volt Battery After Changing The Wireing And Installing Good Grounds A 6 Volt Battery Does The Job Every Time We Made A Beliver Out Of Him

    Hudsonly

    Paulargetype
  • SamJ
    SamJ Senior Contributor
    Agreed, agreed, agreed. 6-volt cables from Dave Kostansek...marvelous. Emery cleaned shining contacts. AND I use an Optima 6 volt battery. They are worth every penny. :cool:
  • [Deleted User]
    [Deleted User]
    Same here, use a Optima 6V battery that has 850 CCA. Starts the car every time and charges perfectly on stock wiring. Plus it fits nicely in a fake tartop case with Hudson logo on side. Looks sweet....
  • [Deleted User]
    [Deleted User]
    Hudson Dave here . Not to rain on any bodies parade but . A 12 volt system charges 12 volts to 14.2 and some even hi-ere then that . A 6 volt system charges more than 6 volts . I put a 8 volt In my 50 Pacemaker never touched the regulator and it worked fine for years . P S If you look close you will find on a lot of 6 volt bulbs they say 6 or 8 Volt systems . LOL:) Hudson Dave
  • Geoff
    Geoff Senior Contributor
    A 6 volt system needs the regulator set at 7.25 volts, and whilst the engine is running, this is the effective voltage that the whole system is running on, that is why bulbs are rated 6-8 volts. If Dave did not re-set his regulator, then the 8 volt battery would have run down to 7.25 volts, and been maintained at this level. A bit like only having the gas tank 3/4 full, the car goes fine, just doesn't go as far! Generally I agree, that the system was designed for 6 volts, it should work at that level. You don't put a supercharger on a worn engine to get it to perform better, you overhaul it.

    Geoff.
  • Unknown
    Unknown
    AMEN , Geoff!
  • Huddy42
    Huddy42 Senior Contributor
    Have also used 8 volt batteries in my 1934 and 1935 Hudson's for years with no major problems, just moved the third brush to adjust for extra voltage, worked fine. As Hudson Dave said all globes are marked 6-8 volt and I never blew any globes in either vehicle.

    The reason I did it was for better lights, my brother and I had service stations back in the late 60's and we used to convert many V.W.'s to 8 volt
  • junkcarfann
    junkcarfann Expert Adviser
    I was just at Advance Auto Parts today and they stock single filament bulbs (like turn signal bulbs) marked "8 volts".
  • SamJ
    SamJ Senior Contributor
    Personally, I think whatever works for you is just peachy keen. 6, 8, 12, 24...whatever. I don't know anything about headlight bulbs so I can't comment. My 1940 was the first year for sealed beams. To get around some patent, the sealed beam fixture had a bulb inside it. Really! One of mine is original. If you don't think they're bright enuff with 6v, check the ground. I believe guru Geoff recommends grounding the bulb directly to the chassis in addition to the normal wiring. It is amazing how a strong ground (earth in NZ) brightens things up. :cool:
  • [Deleted User]
    [Deleted User]
    Alot of good information shared here, that is what i love about this forum i learn alot from it.
  • Unknown
    Unknown
    well I am using an 8 volt battery for now because the engine needs to spin over faster to get her going with only 40 lbs compression in a couple of cylinders. After the engine is reworked we'll see.
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