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aerofurb

Well Known Member
Could any of the already flying gang let me know roughly what ammeter readings they're seeing in flight. I know there are many variables like with the lights option and dual EFIS etc.

I'm thinking of installing the SkyView system in my 12. Although I understand Van's is looking at SV as a future development I may get to the avionics side of things before it becomes a factory option (we can vary avionics in the UK, we aren't limited by LSA law).

I'd like to know what spare capacity the Rotax alternator has in normal use - particularly if I went along the lines of dual SV displays....
 
Currently, the readings on the Dynon are jumping all over the place. Readings would not tell us much until Dynon figures out how to read the voltage signal better on the Rotax. The max is 18 AMPS without adding an optional alternator. I would think you could easily run a Sky View, audio panel, lights, and AP at cruise speed. On the ground it might be lacking a little at night.
 
RV-12 ammeter

The ammeter in the RV-12 shows battery charging current. After the battery is charged, the ammeter will not show much current, regardless of the electrical load demanded by the aircraft. That is unless the alternator can not meet the demand, then the ammeter will show the battery discharging current.
Van's should have located the shunt to measure the current used by the aircraft, IMHO. Then the meter would be called a load meter, not an ammeter. After certification, I will turn my ammeter into a load meter.
Joe
 
Thanks for the replies. I had a VM1000 in the Rv-6 and at work our fleet of PA-28s use 'load' ammeters and I hoped that Dynon would do the same.

We're strictly Day/VFR in the UK so lights are strictly on the 'be seen - be safe' side of things in the air and don't need to be on when on the ground normally, so hopefully cruise engine speed should keep everything lit up.

I'll do some calculating.
 
Load meter

PA-28s use 'load' ammeters and I hoped that Dynon would do the same.
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It is not Dynon's fault. The Dynon only displays the signal that it receives from Van's Control Board. The ammeter can be converted to a load-meter without too much work if desired. I can provide details if you are interested.
Joe
 
Load meter modification

Hi Joe, It would be great if you could provide details, as the current system is not of much use. Best regards, Vern
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Buy a 22,000?f 25vdc capacitor (higher voltage is OK, lower is not). And buy an inline 30amp ATC fuse holder. Do NOT buy a fuse holder made for AGC or glass fuses because they are prone to failure. Here is a picture of an ATC fuse holder: http://www.drillspot.com/products/55566/Bussmann_HHD_Fuse_Holder?s=1

Disconnect the negative lead from the battery.

The capacitor is polarity sensitive. If connected backwards, the smoke will get out. Connect the positive lead of the capacitor and one end of the inline fuse holder to the big fat terminal on the load side (NOT battery side) of the battery master contactor. Connect the negative lead of the capacitor to ground. Remove the 30amp Main fuse from the Control Board and put it into the inline fuse holder. Put a 3amp or 5amp fuse into the Control Board Main where you just took out the 30 amp fuse. A fuse should be in this slot to connect the on-board capacitor (not required but desirable).
On the back of the control board is a big plug with two fat wires. The passenger side wire comes from the battery. The pilot side wire comes from the alternator. Cut the alternator wire at the correct point so that it can be pulled forward through the firewall grommet and connect to the free end of the inline fuse holder. Behind the panel, put tape or heat shrink or an insulated butt connector on the end of the cut wire. This wire can be used for another circuit if desired (with the extended circuit protected by the proper size fuse in the Main slot).
You are done. Connect the negative lead back onto the battery.
Current from the alternator will charge the battery without going through the load meter shunt. You will no longer have any indication of battery charge or discharge current. However, if the voltage is above ≈ 13.5, then you will know that the battery is charging.
Now that there is only one big fat wire going to the Control Board, any current flowing through the on-board shunt will be current used by the aircraft: a load-meter. It does not matter if the current is coming from the alternator or from the battery (if the alternator fails); the load-meter will show the total load. You can turn equipment on or off and watch the AMPS display on the Dynon go up or down, that is if Dynon fixes the erratic reading that builders are seeing.
Disclaimer: I have not tested this modification and am not recommending it. Do it at your own risk. Tell your survivors not to sue me! :D
Joe

PS Instead of cutting the alternator wire behind the instrument panel, it can be cut at the existing splice that is about 3 inches from the voltage regulator. Insulate the cut end that goes to the panel. Attach a new wire to the two joined wires from the regulator and connect the other end of the new wire to the inline fuse. Doing it this way keeps all modifications forward of the firewall. And if you do not like the new circuit, it can be restored to original condition. The capacitor can be mounted with a cushion clamp to a starter contactor mounting bolt. The negative capacitor lead can be attached at the same mounting bolt. Use a short piece of 20awg Tefzel about 3" long between the positive lead of the capacitor and master contactor fat load stud. This will act as a fuselink in case the capacitor ever shorts out.
 
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Mich48041 said:
It is not Dynon's fault. The Dynon only displays the signal that it receives from Van's Control Board. The ammeter can be converted to a load-meter without too much work if desired. I can provide details if you are interested.
Joe
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I'm not flying a RV-12, but I still prefer the Van's method over a load meter. Along with a volt meter to keep track of my alternators health, the ammeter is keeping an eye on the battery condition.

I once flew for about a half hour, after accidently turning the alternator current off. By watching the ammeter, I could easily tell when the battery had regained it's charge.

Once again, this is an area where many like one method, and the other half prefer the other way...

L.Adamson --- RV6A
 
personal preference

Once again, this is an area where many like one method, and the other half prefer the other way... L.Adamson --- RV6A
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I agree that it is a matter of personal preference. And either way is an improvement over the idiot light of some older airplanes. A nice feature of modern EMS is a low voltage alarm that will remind one that the alternator is shut off. Of course with the RV-12, the alternator can not be shut off without shutting off the master switch too (except for pulling the main fuse).
Joe
 
To check your load current with an ammeter connection, just shut off the alternator field and then the load, minus the field current of 2A or less, will come from the battery.
 
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