Ammeter indication erratic

[kai]

Hello,

last year we bought a used RV-9A. The indication of the ammeter is erratic. As soon as the engine is running and the alternator is online, the indication fluctuates between -5A and +5A.
Has anyone an Idea how to solve that problem?

Thanks,

Kai.

[Walt]

It might help if you gave more info.. what type of alternator and regulator?
Voltmeter readings?

[jsharkey]

Originally Posted by kai

Hello,

last year we bought a used RV-9A. The indication of the ammeter is erratic. As soon as the engine is running and the alternator is online, the indication fluctuates between -5A and +5A.
Has anyone an Idea how to solve that problem?

Thanks,

Kai.

I have a Van's ammeter in my -6 and it does the same. I also have an Alternator low voltage warning light so at least I know that it is working.

I think that the "electronic" Van's ammeter gets overwhelmed by noise when the current through the shunt is close to zero.

Interested in others' experience - or fixes.

[rocketbob]

Check your alternator and regulator, your ammeter is working as it should.

[FlyingArcher]

A frend of mine also had erratic reading on his ampmeter until he found a slipping alternator belt during his first annual condition inspection.
The belt had a slightly different shape than the pulley groove and obviously caused it to slip.
With a new perfectly matched belt, erratic readings just disappeared.
Hope this helps

[kai]

Thanks for the fast response!

Due to noise issues we removed the 35Amp alternator and installed a Plane Power 60Amp alternator with integrated regulator. It?s a AL12-EI60/B, baught via Van?s.
The issues was there before, with the old alternator. A slipping belt can be excluded. And yes, it seems that it is only at low current.
Main Bus voltage is at 14.3 V.

If there is a overwhelming noise, would it help to replace the wires from the shunt to the ammeter with shielded ones?

Thanks for the help,

Kai.

[jsharkey]

Originally Posted by kai

Thanks for the fast response!

Due to noise issues we removed the 35Amp alternator and installed a Plane Power 60Amp alternator with integrated regulator. It?s a AL12-EI60/B, baught via Van?s.
The issues was there before, with the old alternator. A slipping belt can be excluded. And yes, it seems that it is only at low current.
Main Bus voltage is at 14.3 V.

If there is a overwhelming noise, would it help to replace the wires from the shunt to the ammeter with shielded ones?

Thanks for the help,

Kai.

Shielded wires - or I have heard simply forming a "twisted pair" with the wires to the ammeter helps.

More of an annoyance than a problem at the moment so I haven't expended the energy yet to scramble behind the panel and "experiment"

[kai]

Ok, I will replace the wires with shielded twisted pair. I will report what I found out.

Thx,

Kai.

[kbelue]

I've seen APRS transmitters cause that when the coax to the antenna is not shielded completely to the antenna.

Kevin Belue
RV-6A
RV-10

[kai]

I have no APRS tracker installed. The erratic indication still exist when the avionic is switched off.

Kai.