C-105 ammeter bounce

[meadowfield 2,545]

just how much should the ammeter be bouncing when the engine is on tickover?

It's a new rectifier and charging fine at 14.4V, but this meter is really twanging around.

[smoreau 658]

I dot think the rectifier is hooked up right. The lead from the amp meter to the rectifier should be the center one. The stater behind the flywheel makes a AC signal output and the rectifier changes it from AC to DC and only uses the positive side of the signal. With what I see on the video, the wires on the rectifier must be crossed or there is a bad ground for the rectifier.

[gregg'shorses 77]

X2

[meadowfield 2,545]

It's not my horse, but my brothers - It's definitely working correctly and does indeed sound like the ammeter is in the wrong lead. He assures me it is correct, but it does stink of being in the AC path hence the equal oscillation - which along with theory decreases as the revs increase as the mechanics cant respond fast enough and average out to zero.

[TT-(Moderator) 1,127]

Wow! - that definitely looks like more than vibration.

The ammeter should be installed in the circuit between the "B" terminal of the ignition switch and the positive terminal of the battery.

Like so:

Wire from battery positive to one post of the ammeter.

Wire from other ammeter post to ignition switch "B" terminal.

Since not all ammeter terminals are marked + or - , turn the key to the "run" position and observe the ammeter needle. If it drops to the negative side, it is wired correctly. If it moves to the positive side, reverse the wires on the ammeter.

[Raider10 3]

The ammeter has bounced about since we first started it. the only thing which looked dodgy was the rectifier was badly corroded and was pushing the resin out. nothing else had been touched on the wiring and it all looked original. i then found one segment of the stator was burnt out. this was repaired with epoxy and the correct guage wire and appears to be ok. thought repairing that and replacing the rectifier would cure it and the wiring loom is brand new too. only thing i havent tried is swapping the ammeter which i might try tommorow, unless its too cold!

[JamesBe1 80]

Sounds like the meter, but before you replace it, try taking a voltmeter and measure the AC on the line going to the meter. There should only be a few millivolts of AC. There should be <14V DC. If you find lots of AC, then it is your rectifier.

[Raider10 3]

Thanks for that JamesBe1.

Tested that and pretty certain its the guage. Got voltmeter on order now anyway. Cheers, Ian.