200 amp meter bouncing

The needle on our 200 amp meter bounces up and down at all RPMs, we replaced the alternator, and it is still doing it. Would this be the voltage regulator under the black cowl hood in front of the cab? Also any idea if this would affect a ACP-6 population planter monitor? We have had our monitor gone through twice and they tell me it is fine, not working right though. Thanks

You should hook your monitor directly to the battery If you dont already.

If the amp meter is really GOOD, then you spiking up and down on amps. That means the alternator is seeing a momentary dead battery... Must be a loose / corroded wire that shows momentary dead battery..

could be any number of things that cause that.

Current flow is a function of battery state, charging system ability, and house load.

Let's say your battery is fully charged, and the charging system is totally able to maintain that load, and you have no house load (no ignition, no lights, nothing at all drawing power. You'll have no current flow, or extremely low, to the battery. That's because the regulator has detected and gone into cutoff.

Let's say all the same above, but there's 20A of house load... you'd see a steady 20A pull on the ammeter.

If you have some device that's got an intermittant draw, the needle of the ammeter will indicate that change.

If you have some limitation in the battery cable, though... or a cracked busbar in the battery, or a shorting plate, or a bad ground cable to the engine or frame, a poor ground from the alternator to the chassis and battery, a bad sensing lead connection (from alternator to voltage regulator), then all sorts of crazy things will happen.

I'd recommend on not ignoring this problem for too long.

No matter what... do NOT limit your troubleshooting to just the primary components. The wiring, and the chassis, and the grounds are also intimately intertwined with this problem. Don't assume ANY wiring is good, especially if you've simply tested it with a continuity meter or ohmmeter... a bad battery cable can indicate zero resistance with an ohmmeter, but put a heavy load on it, it'll fail to carry current... and you'll get wierd issues from all over.

Edited by DaveKamp - 23 Apr 2017 at 9:13pm

Could be the regulator points aren't buzzin but more like sticking and then letting go and repeating... maybe a little cleaning of both the upper and lower points might alleviate the problem... just an opinion

Could be two things. Corrosion on the contacts in the VR, (if external VR) or as Leon mentioned, bad ground. The system could be searchin' for a ground. Its always good to install an external ground strap off the chassis of the VR to make sure its grounded correctly. Corrosion or rust gets under the VR's chassis mounting loosing the ground. That in turn causes a fluctuation in regulation causing "spiking" due to the poor ground. Sometimes removing the VR, cleaning up the grounding foot and adding a aux. ground strap or wire and running it to a good engine or tranny ground or right to the Battery. If the problem still exsists, a shot a Brakekleen or tunner cleaner on the regulator contacts may remove the corrosion. If the contacts show signs of being burnt, its probably best to renew the VR. If you do that, make sure you get the correct VR that will work with the Generator you have. Get the number off the Gennie to get the correct VR. HTH.
Steve@B&B