Batt Amps flashing - voltage regulator problem?

Chris,

Its interesting that your battery voltage is as it should be but your amp meter is showing a discharge.  Does it ever go positive?

When you first start the engine (and have reached 2500 RPM so the alternators switch) do you see a positive charge rate (4-8 amps) while the battery recovers from cranking the engine?

Have you verified that there is normally no continuity between the ground plates of regulators A and B? There should only be continuity if start power or emergency power is applied. Normally these should be isolated.  

As a point of interest, it’s a good idea to get some electrical loads turned on early after starting the engine so the shunt regulator does not have to work as hard to keep the voltage down. With a very light load the regulator will produce more heat.

I see many with Dynon displays and some others that will read amps at -3 to +4 during normal flight. It bounces around some. I have friends with a couple thousand hours on their planes and it has always done this. My Flight Design with Dynon instruments did this for 1800 hrs. without any issues. My batteries would last 4-5 years without any problems.  The voltage always read .5 volt low due to this too. Mine would read 13.6 volts. This can be very normal. Plus it can depend on how much electrical draw your plane has. I called Dynon and they told me it was normal because they thought the Rotax had kind of a Quote: "dirty electrical system".

Bottom line it could just be the instrument and the way it's wired to the engine.

Hi Roger,

You have seen a lot more aircraft than I have, so that’s good information. The OP has a Garmin G3X, but I assume the same conditions could exist as you describe. However I found it concerning that for the first 14 hours of flight this was not happening.  I don’t like unexplained changes.  If the gauge is accurate, a battery discharge during cruise flight indicates the alternator is not keeping up, or more accurately described, it means that the battery voltage exceeds the alternator output voltage at that point in time.  Maybe I’m overly cautious because of the problems the charging systems have had on the 912iS, but I’m still suspicious about why this changed.  

Yes, I do see + Amps after star-up, while the battery is recovering.  And like Jeff, I'm concerned by the change in behavior, since I didn't see this during the first hours. 

Jeff asked about continuity between the ground plates of regulators A & B -- I'm afraid I don't know what these are or where to test them.

Today, following a suggestion from someone on the Van's Aircraft Forum, I changed a configuration setting on the G3X to expand the "deadband zone" from +/- 0.5 Amps to 0.8 Amps, hoping the warning flashing won't go off -- that sort of addresses Roger's comment about a "noisy" generating system.  When the weather ever clears, I can find out if that "makes the problem go away".

Chris, in order to better diagnose the problem, it is necessary to check the wiring you have on both Amps Shunts, and the configuration you have on the G3X Engine sensor (electriical in this case).

Shunts can be connected in such a way that you might have positive and negative readings, but you need to know how these are connected. If the shunt is in series between master solenoid and aircraft loads (only), you could read always negative or always positive Amps (depending which way the cables are connected to GEA24. If the shunt is connected however on other configuration, it might show positive or negative readings depending the flow of current (to or from the battery).

Try to check this.

I also recommend to follow Rotax Install manual, in order to check GEN A GND to GEN B GND (NO CONTINUITY). Look for figures on the Rotax 912iS install manual.