Ammeter Confusion

richardpope50 · Post by **richardpope50** » Wed Jan 08, 2014 5:38 pm

So the problem appears to be the use of stainless steel bolts. As I had an M6 SS nut between the fuse terminal and the cable terminals on both ends. SS is 4 times more resistant than steel therefore the SS is acting like a heater element and it got hot. It also accounts for my voltage drop.

I cannot test this theory until I get the car started and that's awaiting some gauge senders due sometime but at least it all calculates out. Something I did not think about when using SS bolts / nuts.

DaveEFI · Post by **DaveEFI** » Wed Jan 08, 2014 6:01 pm

Ah - right. If you'd used SS to simply clamp one brass terminal against another, you'd probably have been ok.

stevieturbo · Post by **stevieturbo** » Wed Jan 08, 2014 9:50 pm

It's still a fair chunk of bolt though, and were any crimp lugs face to face with the actual conductive metal ?

It's possible it is a factor...I'd still struggle to believe it was the cause.

richardpope50 · Post by **richardpope50** » Wed Jan 08, 2014 10:45 pm

The bolts are M6 (it's a close up photo) and there was an M6 nut between the fuse contact and the cable ring terminals so the current went though 5mm or so of SS twice. A friend calculated the resistance and it more or less equalled the voltage drop I got. Just goes to show what can happen when you do not think of such things.

stevieturbo · Post by **stevieturbo** » Wed Jan 08, 2014 11:14 pm

Well maybe, I still think it would take a huge amount of current to heat up an M6 bolt that much....but Ive never tried it myself.