Flickering alternator gage.

[patrickt]

Take a nice picture, with a reasonably high resolution, of your engine compartment kind of from overhead, and I'll draw you the connections on it. I mostly want to see the alternator, the starter solenoid if you have one (and I mean the little four post FOMOCO solenoid that mounts to the firewall or fenderwell, not the starter motor) and the battery. The easiest, safest, and for surest method is to run a 10 or 12 gauge wire from the alternator to the battery connection at the starter solenoid.

[chucks1]

Originally Posted by patrickt

Take a nice picture, with a reasonably high resolution, of your engine compartment kind of from overhead, and I'll draw you the connections on it. I mostly want to see the alternator, the starter solenoid if you have one (and I mean the little four post FOMOCO solenoid that mounts to the firewall or fenderwell, not the starter motor) and the battery. The easiest, safest, and for surest method is to run a 10 or 12 gauge wire from the alternator to the battery connection at the starter solenoid.

I've been perusing this thread as I have an ammeter issue similar to that noted by the OP and have a question about this shunt wire, which I'll eventually get to.

My SPF ammeter started a constant flickering on both sides of 0 last driving season with no correlation to electrical load. It was just a constant flicker from the time I started the car until the time I shut it off.

I noticed this behavior after having replaced my 11 year old battery, so began troubleshooting there. A load test on the battery says it is good. The battery reads ~14 volts after taking a drive. I have checked and changed battery terminals (they are marine brass) and am confident they are good. The battery ground is good, as is the engine to frame ground. I also added a 12 gauge ground between the VR and the engine block.

After all of the above there is a new symptom; the ammeter needle will occasionally flicker as initially noted, but then read more normal for a bit before taking a nose dive out of sight past 50- and then back to ~0 where it will read normal before starting the behavior all over again.

At present I am running 12 gauge wires from the battery to the cockpit so I can put an analyzer on it to see if there is any change to battery/charging that corresponds to the ammeter dips. Planning to do that test hopefully this weekend.

As to the shunt, am I correct in understanding this is simply a 12 gauge wire from the battery post on the solenoid to the battery post on the alternator? And doing so will route some current away from the ammeter to hopefully get a more normal reading from the gauge (assuming I have no other issues)?

I'm not much with electrical issues, so appreciate any assistance . . .

Chuck

[patrickt]

Originally Posted by chucks1

As to the shunt, am I correct in understanding this is simply a 12 gauge wire from the battery post on the solenoid to the battery post on the alternator? And doing so will route some current away from the ammeter to hopefully get a more normal reading from the gauge (assuming I have no other issues)?

Well, kind of.... Putting a wire from the solenoid to the alternator will bypass the ammeter, but it will bypass other stuff as well. If you look up at Bob P.'s post with the picture of the shunt wire he has it as just going from one post of the ammeter gauge to the other post of the ammeter gauge -- that's like a three inch wire. That's a true shunt wire. I prefer to run a wire from wherever the first convenient connection is on each side of the ammeter which, for me, happens to be a circuit breaker connection and a fuse box connection both on the engine side of the firewall. But that's on an ERA, every manufacturer is different. OTOH, if my ammeter was really, super-duper easy to get to, like being right out in front of my face, so that I didn't even have to bend my back, much less crawl under the dash like an eel, then all I would have done is exactly what Bob's image shows.