Joined: Dec 22, 2006 Posts: 79 Location: Hartsville, SC
Posted: Sat May 30, 2009 6:06 am Post subject: Why 24 Volt
I don't think I've every seen this topic discussed. I was curious about why the military went to 24 volt systems. What is the advantage over 12 volt set ups?
Jack _________________ 50 M38
51 M38
Joined: Apr 14, 2005 Posts: 196 Location: Van Buren, Arkansas
Posted: Sat May 30, 2009 7:45 am Post subject:
One reason, and I'm sure there were others, was
to run the military radios, which were 24 volt. Some
'jeeps' had an auxiliary generator mounted between
the front seats, running off a belt from the transfer
case through a hole in the floor for radio voltage.
Going to 24 volts freed up this space for other things,
reduced complexity, and looked better.
Military Vehicles magazine discussed this a few issues
back. I've learned a lot about various vehicles and
how they work there.
Weight, amperage, volume and conformity are the reasons.
1-Weight-24 volt components are generally lighter .
2-Amperage-This is current and when it is high there is more heat and greater risk for damage. As voltage increases and resistance stays the same the amperage is reduced.
3-Volume-Generally 24 volt motors and such are smaller in size.
4-Conformity-In 1948 NATO made the 24 volt system standard and we simply followed suit.
Don't confuse the large size of the 24 V 25 amp generators as contrary to my statements above. If you were to get the same relative power in 12 volt you would need over 60 amps which would dictate a generator roughly 1 1/2 times the size of our current 25 amp 24V generator.
Tactical military radios during WWII and up through the Korean war were for the most part 12 volt. The WWII Radio jeeps or MZ's as they were called had a PTO driven 12 volt generator in the center of the floor. The CJ/V35 had the same set-up 12 volt PTO powered generator in 1950. Today most modern radios are capable of using anything between 6 and 32 volts.
Aircraft started making the 24 volt switch during WWII to save weight and at the same time increase the power of it's electric motors.
By 1957 most auto makers had switch from 6 volt to 12 volt for all the same reasons above (of course it took the half a century to up date). Since the bean counters at the auto makers planning sheds base all equipment changes on the mighty dollar of return they usually resist major changes for many years longer then the military and aviation industry where performance is the more prominant driving factor. The lates direction the aut industry is looking is a new 42 volt system again for all the same reasons at the begining of my post. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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