Ammeter Shunt Questions

[Jared]

Can the D-180 display an ammeter reading for two different alternators, each with it's own shunt? I'm planning to use a 60A main alternator and a standby SD-8. Also, is the Dynon adjustable so that I could use a the B and C 10A 50mV?

 

[pbennett]

You should find relevant info in this thread.
http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1280253202

Peter

 

[Jared]

Peter, thanks! That was certainly a starting point. Is it safe to figure that if the skyview doesn't have dual ammeters, then the d180 doesn't either? I could live with the switched input idea. In that case, what kind of shunt should I be looking for? I read somewhere that the dynon needs to have the mV's equal the amps, is that correct?

 

[pbennett]

Yes, my EMS D10 uses a shunt of 1mv per amp. Size the shunt so it will carry at least the max amps the alternator will deliver. I'd suggest you just get two Dynon shunts that will carry 60 amps. They are a nicer quality than the shunts I can source from my local electronics supplier. Also I'm not aware of any calibration that would enable you to use the B&C shunt.

Peter

 

[Jared]

So is there any downside to using a 60 amp shunt on an alternator that only puts out 8? I guess it would be like running a 4AWG wire on a circuit that only needs one amp. Clunky, but not detrimental.

 

[pbennett]

Correct. As long as it generates 1mv for each amp it will do the job, regarless of how many extra amps it is capable of handling. But if you are pushed for space, you might want to source a physically smaller, lower current version.

Peter

 

[skysailor]

As regards Skyview, I have the 60 amp shunt which came with the sensor package. The problem for me is that the shunt is actually marked 40A on the unit. I am considering purchasing a 100A unit which Dynon says will work as long as it is 1mV/A. The question for Dynon is this, is there a max mV the EMS will tolerate? For example, if I found a 300A 300mV shunt, would the Dynon tolerate indicating 300 amps if that was somehow generated (for the example)? I know the unit would only see 300 mV in this case but would that be tolerated without damage?

 

[dynonsupport]

The shunt we sell is marked 40A/40mV in order to show you that it is a 1mv/A shunt. It is rated for 60A.

If you do use another shunt, the most we can read is 100mV, or 100A. 300mV should not damage anything, but it will not read correctly.

However, we do not recommend the shunt be in the path of the starter motor, which is the only reason you would see 300A in most planes.

 

[skysailor]

Having reviewed the install manual, I think mounting the shunt in "position A" should get me what I need. Thank you for the timely response.