1929 A: 12volt alternator on 6 volt system??

[dwhitehead]

Cranks but won't start condition. I see a 12 v alternator with a 6 volt battery, lights are still 6 volt. There is a 30 amp fuse on top of the starter that keeps blowing so I'm not sure the solenoid is getting power. Pretty soon the battery was unable to crank the starter.
I took the battery to be tested and it failed.
Does anybody know a reason why a 12 volt alternator might have been installed during the "to the frame" rebuild. Unable to ask the man who did the work for my father-in-law. Dad did drive it in this configuration and always kept it on a 6 volt trickle charge.

[Mike V. Florida]

It could be a conversion of a stock 12 volt alt to 6 volts.

[jrelliott]

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Would suspect that the alternator had been converted to 6V alternator otherwise bulbs, coil and battery would have failed. 6V battery does not like having 13.6 to 14.2 Volts forced into it and would have deteriorated quickly or blown up.
The 30 amp fuse should not be a part of the starting circuit, it is part of the charging circuit. There should not be a starter solenoid on a Model A. There is a starter switch that mounts on top of the starter that connects the battery directly to the starter when activated by the starter button on the floor. This switch should have the 30 A fuse holder attached on the side.
Suggest that you get a small 6v bulb and attach alligator clips using some wire to the bulb so you can place this across the fuse socket after the fuse is removed to check where you have a short. If the light comes on when nothing is on you have a short somewhere. Keep pulling wires from the back of the alternator then from the terminal box until the short is found and the light goes off.
If you have a one wire alternator, it will draw the battery down just sitting there unless you pull the fuse as the alternator will draw some current when sitting. This may be the reason your dad kept a trickle charger on it.