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8V battery in an M-5 won't stay charged

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  • Electrical: 8V battery in an M-5 won't stay charged

    Someone brought me his 48 M-5 to work on. He has put an 8V battery in it but still has the 6V generator. He says the battery won't stay charged up. even a new one. I was just wondering if a 6V generator will even charge an 8V battery.

  • #2
    Originally posted by Buck View Post
    Someone brought me his 48 M-5 to work on. He has put an 8V battery in it but still has the 6V generator. He says the battery won't stay charged up. even a new one. I was just wondering if a 6V generator will even charge an 8V battery.
    It will, if you adjust the regulator to the higher voltage.
    JDP Maryland

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    • #3
      I've heard that in late '55 Studebaker retrofit 8 Volt batteries into some 259 V8 equipped cars to help fight the 'Six Volt Blues'. (With voltage regulators adjusted up) Never seen one..but it WOULD make sense considering.

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      • #4
        Put a 6 volt battery back in it, 8 volts just mask problems and create more problems! Is the starter in good shape? how about all the grounds, ground straps, pos battery cable? Once had a car that had so much paint on the end of the starter and the engine adapter plate that there was a 2 1/2 volt drop across it! Cleaned a LOT of paint off that one and the pos cable and where it hooked and wound up with 1/4 volt drop, it started great then!

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        • #5
          Originally posted by radiotech View Post
          Put a 6 volt battery back in it, 8 volts just mask problems and create more problems! Is the starter in good shape? how about all the grounds, ground straps, pos battery cable? Once had a car that had so much paint on the end of the starter and the engine adapter plate that there was a 2 1/2 volt drop across it! Cleaned a LOT of paint off that one and the pos cable and where it hooked and wound up with 1/4 volt drop, it started great then!
          Maybe in sunny California.......................!

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          • #6
            8 volt battery

            Originally posted by radiotech View Post
            Put a 6 volt battery back in it, 8 volts just mask problems and create more problems! Is the starter in good shape? how about all the grounds, ground straps, pos battery cable? Once had a car that had so much paint on the end of the starter and the engine adapter plate that there was a 2 1/2 volt drop across it! Cleaned a LOT of paint off that one and the pos cable and where it hooked and wound up with 1/4 volt drop, it started great then!
            I agree with your post. If the starter is getting the full monty it will start even in MA. To assist with cold temp starts, in September change the oil with 10 weight it will assist your starter by 10 - 15 %.

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            • #7
              An 8V battery is a sure fire way to burn out lights, smoke the radio, burn points, and cause other problems. Better to fix whatever is wrong, making the 6V setup not work well, or better yet, just convert to 12v. I've seen several older tractors that have 8v batteries, and for them it's not such a bad deal since they don't have much in the way of lights etc. to burn out, but for cars and trucks, it's a poor solution to hard starting. JMHO
              Corley

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              • #8
                Put a six volt battery in it and fix the rest of the electrical system to work properly.

                To answer you directly, and if he insists on staying with eight volts, adjust the regulator up to give an eight volt charge. If the regulator is still set for six volts, the eight volt battery will never get fully charged.
                Gary L.
                Wappinger, NY

                SDC member since 1968
                Studebaker enthusiast much longer

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                • #9
                  A 6 volt system in good working order should suffice.
                  Slow cranking and resulting hard starting can be the result of excessive resistance in one (or both) of the starter circuits.
                  With a fully charged battery a voltage drop test while cranking will make it clear what component(s) or connection(s) are causing excessive voltage drop.
                  There are actually a few more "pieces" to the circuit to test than shown here.

                  Plus, the ground circuit too.

                  MUCH more effective than maintenance or parts relacement based on this -

                  Last edited by Dan Timberlake; 09-19-2013, 03:32 PM.

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                  • #10
                    Get rid of the 8 volt battery. If you adjust the regulator to full-tilt-boogie it will cause it harm. 6 volts is ok with clean connections. cheers jimmijim
                    sigpicAnything worth doing deserves your best shot. Do it right the first time. When you're done you will know it. { I'm just the guy who thinks he knows everything, my buddy is the guy who knows everything.} cheers jimmijim*****SDC***** member

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                    • #11
                      Well...most automotive electrical systems are designed to deliver a little more juice than the rated voltage. Otherwise, why would they need to be "regulated." Given proper maintenance, a six volt system works great.

                      The curious part of this particular problem is in the statement from the owner that, "It won't stay charged." That requires a bit more clarification. If, while running, the amp gauge registers positive, then the system is working. Not staying charged after sitting for a while is an entirely different problem and suggest that there is a "drain" somewhere in the electrical circuit. Could be anything from a bulb with an internal short that allows current to drain without lighting the filament, (very rare), bad brake switch, or any number of places, where corrosion, bare wires, or other unseen places, a small current drain leeches off current without involving a dead short which would blow fuses or (worst case) a fire.

                      If the vehicle has a patchwork of that horrible old original wiring and decades of "fixes"...the current problem is not surprising.
                      John Clary
                      Greer, SC

                      SDC member since 1975

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