battery discharging in flight

[BigJohn]

Steve, looks like your regulator is dying at about the same point mine did. I moved my new one to the new location away from the heat. Very happy I did. FWIW department.

[Paris12Man]

Thanks John. Is the new location inside the instrument bay? Any pictures of new install location? Steve

[Bill_H]

See http://www.vansairforce.com/communit...d.php?t=117720 for new location details.

[Paris12Man]

Thanks Bill. Are these plans available on Van's? I can't find them. Steve

[tomkk]

Resurrecting an old thread but it seems the most appropriate place. Sorry for the lengthy post ...

First a bit of history. I've been struggling with voltage regulators, seemingly forever. I had a Ducatti fail early on (65 hrs), probably a problem with the connector. (I currently have almost 300 hrs on the plane.) Another Ducatti went to a low voltage charge and I decided to try the John Deere VRs. I've tried a couple of them but they seemed to have a lower than recommended charge rate (13.3v or so). I tried boosting that a bit by adding 1 or 2 diodes to the VREG CNTRL line to the VR (the signal that goes to the "C" terminal of the Ducatti & the IGN terminal of the JDs) with some success but generally have been barely able to get up to the 13.8v - 14.2v that I think is more normal. I do not know whether any of this is related to my current problem below.

I just had another Low Voltage alert from SkyView with a John Deere AM101406/MIA881279/JDR1406 VR. I swapped in another VR and the result was the same - not charging at any RPM. I put the battery on a battery charger and it was down to about 35% capacity. I measured the voltage on the VREG CNTRL wire at the VR and it was only 1.75v. That was measured between that wire (disconnected from the VR) and airframe ground with the engine OFF and Master ON. I had previously (back in 11/2015) measured that at 11.52v when shooting another problem. I think that should always be near battery voltage, right? All fuses are OK.

I looked at the RV-12 schematics and that VREG signal looks like a pretty straight shot from the VR, through the AV-50000A Control Module, the AV-50002 Ignition and Start module & Master SW, to the AV-50001 Switch & Fuse module. It goes through a 1A fuse in the S & F module but it seems like I'd get a 0v reading if that fuse were blown, not 1.75v.

Not exactly sure how to shoot this problem. Next time I go out I intend to:

• Back up from the VR, through the AV-5000x modules and check the VREG voltage at each connector. At some point I should find something near battery voltage.
• Joe pointed to a "Testing Rotax 912/914 Generator and Regulator/Rectifier" article some time ago that I'll try but until I can find the issue with the VREG line I doubt this'll be productive.
• ?????

I'm pretty much at a loss here about any other approaches. Any thoughts about anything else I can do to shoot the problem?

[DHeal]

Install a new-style DUCATI R/R under the avionics shelf as recommended by Van's. At the risk of jinxing my unit, my replacement/relocated DUCATI R/R seems to be surviving for the past 380 hours.

[tomkk]

Originally Posted by DHeal

Install a new-style DUCATI R/R under the avionics shelf as recommended by Van's. At the risk of jinxing my unit, my replacement/relocated DUCATI R/R seems to be surviving for the past 380 hours.

Sorry, should have mentioned that. Already inside under avionics shelf. Has been there since the build ...

[Mich48041]

If there is not battery voltage on regulator terminal "C", then the circuit MUST be open. There is either a bad connection or else the 1 amp fuse is blown. Yes, the fuse can be blown even with 1.75 volts on terminal C. The voltage could be coming through the regulator from terminal B. Remove the small yellow wire from the regulator, then measure the voltage on the yellow wire.
Try taking the AV-50001 SWITCH & FUSE MODULE D-Sub connector apart and measure voltage that comes from the 1 amp fuse. If the fuse is OK, then other possibilities are a loose or broken D-Sub connection or a bad master switch.

[tomkk]

Thanks Joe.

Originally Posted by Mich48041

If there is not battery voltage on regulator terminal "C", then the circuit MUST be open. There is either a bad connection or else the 1 amp fuse is blown. Yes, the fuse can be blown even with 1.75 volts on terminal C. The voltage could be coming through the regulator from terminal B. Remove the small yellow wire from the regulator, then measure the voltage on the yellow wire.

Sorry, I wasn't clear. The 1.75v was measured on the disconnected small yellow wire (yellow wire to airframe ground).

Try taking the AV-50001 SWITCH & FUSE MODULE D-Sub connector apart and measure voltage that comes from the 1 amp fuse. If the fuse is OK, then other possibilities are a loose or broken D-Sub connection or a bad master switch.

I'll do that next time out. Sure hope it's not the Master - I had an intermittent Master a year or so ago that I replaced - the lead time for the switch was 6 weeks

[Mich48041]

Did you buy the master switch from Van's?
To check the master switch, disconnect the D-Sub connector from the AV-50000A that goes to the IGNITION MODULE. Then turn the master switch on and measure continuity between pins 13 and 14.
If the master switch is bad and you do not want to wait until a new one is delivered, regulator terminal "C" can be jumpered to terminal "B". The disadvantage of doing that is that in case of smoke in the cockpit while flying, the master switch will not shut down the electrical system. It would be necessary to pull the alternator fuse.