Would it be worth looking at the pulley ratio, to check its the same as the engine it came off. I would have thought you meed a ration closer to 1:2, to get the alternator running fast enough at idle.
I would prob do that if I could James... but... the drive pulley can't go any bigger (as it would foul the crank nose casting) and the alt pulley is fixed.. I think it should at least prolong the life of the battery for 'testing' purposes as it kicks out 14v at higher revs. Just need to make sure I don't sit in traffic (and there is no chance of that!!)
If you have the original Austin 7 switch panel it had a red light for not charging and an amp meter. You could build one up with your LED and a volt meter as a homage to the original? Like the build and envious of the car and garage!
Charging voltage is too low for a decent alternator, and will not charge the battery meaningfully. Your belt may require some dressing, or tightening to remove play. Shoudn't be more than about 1/2" of sideways play in the belt. Earlier shots showed it waving around quite alot!
I just need it to 'not drain/rely on the battery'... I have very little in the way of electrical equipment to drain the battery (no lights, no heater, no wipers, no electric windows!).. I'll report back after road testing! (assuming I make it back.... ;-)
My point is that the belt is either slipping or the alternator is faulty. The charge voltage has to be higher than the float voltage otherwise you're just carrying a brick!@@thebracketfactory
Alternators are designed to produce full voltage at most speeds, unlike dynamos. Alternator pulley is an integral part of the alternator so cannot be changed. Cam shaft pulley would need to be larger, but not practical. My bet is that the alternator is faulty or the belt is too loose.@@robbell4339
I’m thinking the alternator’s not turning fast enough. If you look at the ratio of the diameter on a regular crank pulley to an alternator pulley it’s about 3:1 at a guess. I think you’re not far off 1:1.
