A7 alternators again....

[Stuart Giles]

Following on from this 'vintage' thread from last year: https://www.austinsevenfriends.co.uk/for...p?tid=6540  On and off (mostly off in between other 'must do' workshop stuff) I have been working on a replacement for a friend's 12v Dynamator which has not been inspiring confidence after I needed to repair it for him last year.

My basic idea was to use a small permanent magnet alternator as fitted to lorry refrigeration units and some garden tractors. They produce an output to charge a 12V battery at up to 14A; low by modern alternator standards, but still a more than adequate 168W output Vs. the 55ish Watts of the A7 unit.

Here's what these alternators look like 'out of the box' the gold coloured drum contains some powerful permanent magnets which rotate around the stator coils in order to provide a single phase  AC output which is connected to an external regulator.

 

The main components:



Machining the stator casting to locate the A7 distributor drive housing.



Assembled on the re-machined Lucas dynamo shaft along with the permanent magnet rotor.



Finished: