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1920 Special Six, battery voltage

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We recently purchased the above car and was inquiring what nominal voltage is correct?  The car came with an 8 volt battery, but I am unsure if this is correct.  My knowledge of pre-war Studebaker's is limited.


Car pictured below.


Thank you


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Your Special Six was originally a 6 volt system. Some people put in an 8 volt battery to help spin the starter faster, usually because the starter could use rebuilt or at some point someone replaced the original 00 size starter cable with something from Autozone made for 12 volts (like #4 or #2 gauge) and it just doesn't have the ampacity needed. The problem with an 8 volt battery is that the generator was designed for a six volt system and trying to pump out something over 9 volts to keep it charged becomes difficult unless the engine is constantly running at a high rpm. Keep in mind that most batteries have a maximum state of charge greater than 2 volts per cell so your three cell 6 volt battery should read 6.3 volts or a bit more when fully charged.  The charging system usually runs at 2.4 volts per cell which is 7.2 volts for a 6 volt battery but the generator has no regulator and the voltage is regulated by an adjustable third brush in the generator which is usually set in the middle and will under charge at idle and over charge some at cruise speed. With this type of set up, most folks would run their headlights during long periods of cruising to prevent an overcharged battery.


My suggestion is to first check for proper size battery cables (0 or 00) - they should look like welding cables and all the connections are corrosion free.  Then move on to starter if a 6 volt battery won't crank it.


Edited by Stude Light (see edit history)
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+1 on what Scott said.  The mechanical voltage regulators in these cars tend to confuse the heck out of digital voltmeters.  I have one that jumps all over the place and another that reads the wrong voltage.  If you can get an analog voltmeter that is your best bet.  My old tach/dwell/volt/ammeter works perfectly and shows 7.2 volts at 1000 RPM on my 6V system.  6V works great, but you have to make sure every connection is clean and tight, use the right gauge wires, and never forget it is positive ground.



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Thank you for the replies.


The wiring to the starter motor appears to be original or an OEM replacement (hard to tell on a 100 year old car) cable.


I was 99% sure the 8 volt battery in the car was incorrect, but I wanted to be 100% correct.


This car sat for probably 10 years in garage and we are slowing working through systems and components before attempting to start the engine.


Thank you again.

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