Re: Rewind the generator?

Posted by Gerald J. on January 19, 2005 at 07:38:30 from (67.0.96.201):

In Reply to: Re: 8v Alternator posted by Norm in Alabama on January 19, 2005 at 06:12:40:

Been there, done that. Learned later it was a total waste of effort.

In a constant speed situation, rewind is the proper action but it cuts the current capability in half.

Where the shaft speed of the generator can be increased (by reducing the size of the generator pulley or by opening the tractor throttle more) all it takes to get 12 volts from a 6 volt generator is a 12 volt regulator.

If you hold the field at 6 volts you will have to double the shaft speed to get 12 volts. And that 12 volts will have the same current capability as the generator did at 6 volts. Double the watts.

If you let the field voltage rise to 12 volts a perfect generator would only need a 41% rise in shaft speed to put out 12 volts. But the speed will need to be more because the field core saturates, probably at less than 12 volts on the coils. The field coils will be dissipating 4 times the power on 12 volts and so the frame will run hotter. 12 volt field coils and the original armature would be a cooler operation, though I've run a 12 volt generator at 24 volts for hours at a time holding it in my hands without it getting too hot to hold.

As said below, 6 volts cared for properly cranked the tractor for 40 or 50 years, going to 12 volts isn't better. An aged 6 volt starter needs bearings and brushes. Probably a new solenoid with clean contact surfaces and the battery wires need to be substantial, nothing from Walmart. 1/0 is a nice size with cleaned battery posts (more often needed at 6 volts than at 12) and all the other connections cleaned. Used to be in a 6 volt car that battery posts needed cleaning about twice a year. In those days my dad insisted on scraping them with a knife blade until the post (and cable end) shined. The modern wire brush doesn't quite achieve that shine but helps a great deal and keeps them more round than my pocket knife ever did.

Gerald J.

Follow Ups:

• Cleaning Battery Posts Andy Martin 08:28:52 01/19/05 (0)

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