6 Volt Generator Output

L

larry/Texas

Senior Member
What should the output of a 6 volt generator be at what RPM. I have one with about 7.4 volts or so at about 1500 RPM. The battery is probably not fully charged. If it is too high or low, what do I do to correct the output?

Working on a 21 stud engine.

Thanks for your help
 
Larry,

It should put out between 7 and 7.2 at 1,375 RPM. I would think that 7.4 is within the ballpark, but some others should weigh in soon.

Kevin
 
Hi Larry, Your 7.4 volts sounds pretty good at 1,500 RPM, but can depend on several things such as battery state of charge and condition and current in amps flowing, loads turned on, temperature, etc. If it has been ok at that then don't touch that voltage regulator. You really need to know what you are doing when working on these and not play around with them. You did not say what car or generator or v/regulator or 3rd brush generator you have. Regards, Kevin.
 
Your voltage sounds good. The problem is if the battery is a little low when you start the engine plus the starter load pulls the battery even lower. After the engine starts the battery is not being recharged until you get up to 10 or so MPH but before that time the coil is still pulling the battery lower. After you get driving at highway speed it will take 20 or more miles to get the battery back up. At night it will take a long time and you may have to set the generator voltage a little higher if you do mostly nigh driving. G.M.
 
G.M. said:
you may have to set the generator voltage a little higher if you do mostly night driving. G.M.
Click to expand...


So, how much higher can the voltage be set without damaging the battery or anything else?
 
Last edited:
7.4 is fine and is indicative of your battery calling for and receiving some degree of charge. Check it again after running for a while and you are certain the battery is fully charged - you will likely see at reading then of 6.7-6.9 volts assuming no other demand (headlights, etc.) is being called for.

Did you change your voltage regulator & if so ensure the new one is properly polarized? Assuming you are properly polarized and the VR is operating properly, and if you continue to be concerned about what is 'right', purchase a yellow manual off of eBay entitled 'REPAIR MANUAL GENERATING AND STARTING SYSTEMS 1933-1947' / 'Ford Motor Company' dated June 27, 1947 in the bottom right corner of the cover. It should also reference 'Form 3672-47 F' in the bottom left corner of the cover. Originals are available for $10-$15 or so. This manual contains the specifications and methods for changing outputs using your voltage regulator adjustments.

Just went through all of this while bringing a '47 Merc flathead back to life and spending a couple of weeks on the charging system, including changing the armature, VR, generator & coil wiring harnesses, etc., as well as 4 trips to a local automotive generator/alternator/electrical shop to test the generator & VR. Mine read 7.4 as well after 'getting it right' and immediately after starting (i.e., minor battery drain). It dropped to 6.7-6.9 at 1,500 rpm+ when the battery was fully charged and no other demand was being called for.

Good luck!;
 
I have the same problem. My 53 f-100 has factory overdrive works great until, I turn on the head lights. it will not shift into OD until I turn off lights. The amp shows + turn on the lights - . hOW DO YOU agjust the voltage regulator?
 
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