Initial experimentation with external shunt ammeter
At the end of all this I hope that there is a set of instructions that will tell us how to eliminate the risk inherent in the non-external shunt system and still have a functioning ammeter. :popcorn:
There might not BE a "complete" way. That is, however, an interesting thought, here's one take-off
If you have looked at the stock ammeter, the "entire meter" is really just a shunt (brass) across the two posts, which generates a magnetic field, and deflects a counterweighted vane needle assembly
So IF that can not be modified, the only real strategies I can think of are:
1....Bring the entire ammeter circuit up to as close to factory as you can, apply the factory equivalent of the "taxi fleet police" modifications and that might just be enough
2....Be happy with less than say, 50A alternator and be careful what you add. No big pumps fans, maybe a stereo. In other words, limit choices
3....Maybe MODIFY the ammeter into a PARTIAL external shunt. I think Bill Grissom ^^above^^ has hinted at this by using a pair of back-to-back diodes as sort of an added external shunt to limit full current through the bulkhead...........Maybe MAYBE this could be taken a step further...........
Maybe you could disassemble the ammeter, file down the shunt to make it a much more sensitive movement, maybe say, 10 or 20A full scale instead of 40, then add a shunt OUTSIDE the firewall to make up the difference.
Food for thought. As Crackedback says, "more than one way to skin that cat"
If and when I get the 74 Scamp into a more "runnable" car it might make a good guinea pig for this testing. Bear in mind I've gotten a LOT "older" in the last year or two, the broken ribs (TWICE!) added a lot to that. So crawling around under a crowded dash is not much fun. The Scamp presently has a bench seat, and those are not much fun to remove. I have to unbolt each back, remove the center, and then unbolt and remove the bench bottom.
