Ammeter

[blueskyMD]

The old Piper stock ammeter I have is not giving me correct reading . Most of the time its sleeping even during the night flight when everything is on. Occasionally it wakes and shows different reading with the same load. What options I have ? The plane is PA32 Lance. I have JPI EDM 730 engine monitor. Does anyone knows if there is some kind of probe available to display current draw on 730 ?

 

[Tom-D]

The old Piper stock ammeter I have is not giving me correct reading . Most of the time its sleeping even during the night flight when everything is on. Occasionally it wakes and shows different reading with the same load. What options I have ? The plane is PA32 Lance. I have JPI EDM 730 engine monitor. Does anyone knows if there is some kind of probe available to display current draw on 730 ?

first option, clean all the contacts on both the shunt, and the meter. see if that helps

 

[Clark1961]

The Piper shunts are somewhat notorious for corrosion on the terminals. Mine is buried behind autopilot stuff so I just put up with the false reading.

I think EI has a voltmeter/ammeter combo instrument. I have a digital voltmeter from the auto-n-airplane parts house. It plugs into the cigar lighter so I can keep an eye on the electrical system.

 

[Tom-D]

The Piper shunts are somewhat notorious for corrosion on the terminals. Mine is buried behind autopilot stuff so I just put up with the false reading.

This theory is why a lot of small inconsequential discrepancies don't get repaired. I understand that you mess with the autopilot to fix the amp meter now you deal with autopilot discrepancies now till dooms day.

Murphy theory ?

 

[coloradobluesky]

Check for loose or corroded connections. Check the ground.

 

[Dan Thomas]

Check for loose or corroded connections. Check the ground.

There are no grounds in an ammeter or loadmeter circuit. If the alternator's ground was bad, the battery would be failing. Things would get dim.

The Piper loadmeter uses a shunt--a strip of metal with a defined but very low resistance--and the alternator's output goes through it. A pair of smaller wires, connected at each end of that shunt, feed the loadmeter itself, which is a milliammeter calibrated to show amperes. The shunt's resistance forces a small amount of current through the milliammeter, proportional to the current through the shunt. If those small-wire connections are loose or dirty or corroded, the loadmeter lies to you.

 

[Cruzinchris]

Quit looking at the ammeter. The voltmeter on your JPI is all you need. To check the health of your electrical system, switch on a big load like a non-LED landing light or pitot heat. Voltage should dip a bit and come back to 13 volts or so +/-.

 

[blueskyMD]

Good point. But the reason I want to check electric load is because landing gear warning light in my plane goes off every now and then and my mechanic wants to know if the gear motor was running at that time and a spike in ammeter will be helpful to find that out.