Amp Gauge Blow Up

[Mongoose930]

Thanks Patrick. Is the wire going to the Ammeter 10 gauge or 12 gauge? I am thinking that most of the current would run through the 10 gauge wire (if that is what it is) and only go through the 12 gauge parallel wire if there is a problem with the ammeter / 10 gauge wire. Great information.

[patrickt]

Originally Posted by Mongoose930

Thanks Patrick. Is the wire going to the Ammeter 10 gauge or 12 gauge? I am thinking that most of the current would run through the 10 gauge wire (if that is what it is) and only go through the 12 gauge parallel wire if there is a problem with the ammeter / 10 gauge wire. Great information.

Right. The resistance of the new 12 gauge line is just a wee bit higher, but not much more, than the existing ammeter line. That allows the ammeter to still work very nicely. I do notice that when you turn on all the fans the "peg" of the needle does not go nearly as far as it once did. Other than that, the readings are just a bit more subdued, but still tell you pretty much everything that they always did. If I disconnected the ammeter entirely and just ran the car on the 12 gauge parallel line, it would probably be alright, certainly for a while, but it might also heat up and you wouldn't want to run it that way forever by any means, but maybe you could. The thing is, if all of a sudden I note my ammeter is acting differently than it has for the last seven or eight years (and it acts very consistently), then I know to stop and investigate. I have to say that's one thing nice about these cars, they tend to give you a little advance notice before they crap out on you. But sometimes that advance notice is really subtle....

[patrickt]

To answer your question on what percentage of the current goes through what path, let's say your ten gauge ammeter line has a total resistance of .003 ohms, which is what one of the internet calculators says a three foot span of ten gauge wire has, and let's say your new parallel 12 gauge line has a resistance of .005 ohms. Now, the difference of .002 ohms is hardly anything, but it results in 62% of the current going through the ammeter and 38% going through the parallel line. Now, let's say something happens and that ammeter goes up to just .01 ohm (in one way, that's still not much). Now the current going through the ammeter will only be half as much as the current going through the parallel line. Move the ammeter up to just 1 ohm of resistance and now the parallel line carries 99.5% of the current. I think I did that right...