More questions from the rookie.


Still playing with heat issues, but a new opportunity has surfaced. While taxiing to the active, my battery charge indication shoed low voltage, fluctuating into yellow. On run-up, the bar still showed slightly more than 12 volts. It usually reads 13.2 or so. I went back to tie down, and quit for day. Later, the battery would not turn engine. On charger all night.


Does the Jabiru have a voltage regulator that may be bad? If so, where is it, and what does it look like?

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Comment by David Gallagher on May 7, 2013 at 7:04am

Don, I sent you a message so we can talk off-line.

Comment by Don Forwood on May 6, 2013 at 10:17pm


Great advice. Flew this morning, and decided to alter my checklist to include waiting til run-up to turn or lights, and to turn off when clearing active.

I also have a heating issue on my 3300. My 601 has a MGL glass, and shows yellow oil temps (220) in climb. CHT's also running warm, # 4 is hottest at 350. Any advice on getting these temps down? 

Comment by David Gallagher on May 6, 2013 at 8:44pm



As Ian states, the Jabiru alternator provides little to no charging at idle RPM.  So if you already have a low charge at start, or if you are pulling a heavy electrical load at idle, battery voltage may show lower than you are already used to seeing.  Assuming you charged your battery when you changed the washer stack-up, you may have also 'solved' your problem just by having a full battery now.


Buss voltage may even show low at cruise RPM if battery voltage is low and it is taking on a heavy charge load.  If I may, I can bore you with a story on how I found this out at Oshkosh 2009 on my Jabiru 3300 powered 601XL.  I left all my lights on (landing, position and strobe) after landing and had a long 20+ minute taxi time to parking with 10-11 amps load.  As overwhelming as Oshkosh can be to the senses, I forgot to turn the landing and position lights off, a good 5-6 amps worth.  At the end of the week, same thing.   I had another long, 40 minute taxi time, for departure with the same switches on and resulting electrical load.  After departing and getting away from traffic, I finally got my cockpit scan back in order and was a little surprised to see only 12.7 volts at cruise RPM.  I started wondering if I had an electrical failure.  In looking at load shedding I finally discovered the extra lights still on.  A few minutes later, it was up to 13 volts and then eventually up to over 14 volts, but not until after at least 20 minutes of flight. 


I looked at the Dynon data afterward and could see voltage steadily drop off after landing until shutdown.  After starting and until takeoff, voltage continued down to nearly triggering my low voltage alarm.  After takeoff, voltage crept slowly up to the typical 14+ volts, probably after the battery was fully charged.  I have only seen this sub 14 volt condition in flight one other time when the battery was low shortly after takeoff.


This is just some food for thought and depending on where you tap your voltage indication, you might see something totally different. These permanent magnet alternators are a different breed, but seem to work well if understood.  Good luck,


Comment by Don Forwood on May 5, 2013 at 2:09pm

I may have caused my own problem.  I put brass washer at bottom of terminals, and then tightened cables down with brass nut on top. I suddenly remembered that this causes some issues on Harley's. Started up, and great charging indications.

Thanks for weighing in on my gripe.

Comment by Ian McClelland on May 5, 2013 at 1:40pm

The Jabiru alternator is rated at 20 amps at cruise RPM. At idle it produces almost zero output.

Also check for poor connections between alternator, battery and regulator.

Comment by Paco Pineiro on May 5, 2013 at 1:07pm


601 XLs came with a regulator on the upper left corner of the firewall, (looking from the front), but you might want to check your battery first.  I had a similar problem and solved it by installing a stronger battery.  On a friend's advice, I went from an Odyssey 625 to a 680 and so far it has solved things. Good luck.


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