Can a Rotax 912 100hp handle these amps?

H. Paul Shuch is a Light Sport Repairman with Maintenance ratings for airplanes, gliders, weight shift control, and powered parachutes, as well as an independent Rotax Maintenance Technician at the Heavy Maintenance level. He holds a PhD in Air Transportation Engineering from the University of California, and serves as Director of Maintenance for AvSport of Lock Haven.

Moderator: drseti

Post Reply
sport flyer45
Posts: 10
Joined: Mon Dec 15, 2008 12:07 pm
Location: Orlando, FL

Can a Rotax 912 100hp handle these amps?

Post by sport flyer45 »

Dynon skyview 10" display - 2.1 amps
Dynon skyview 7" display - 2.6 amps
Dynon GPS Antenna - 0.1 amps
Dynon ADAHRS - 0.15 amps
Dynon ADS-B - 0.2 amps
Dynon C25 Com Radio - 3.0 amps
Dynon intercom - 0.1 amps
Dynon Xpndr mode- S Class 1 - 0.4 amps
Dynon backup battery - 1.0 amps
Dynon engine monitoring module - 0.11 amps
Dynon A/P module - 0.05 amps
Dynon WI-FI adapter - 0.1 amps
USB charging jack - 2.1 amps if charging I- Pad
ELT- 406 - 0.2 amps
Dynon SV-42's servos (pitch & roll) - 4.0 amps
Whelen - microburst lll - strobes - 1.2 amps
Whelen - microburst lll - Nav lights - 0.25 amps
Ray Allen trim servo - 1.0 amps
Facet electric fuel pump - 1.4 amps
LED landing lights - 0.2 amps

TOTAL Amperage: 20.26 (Rotax internal alternator only)
Landing: 11.52 amps @ 3,000 RPM in the pattern
Take-Off: 13.11 amps full power
Cruise: 14.21 amps if flying with A/P on
I would like anybody's thoughts and opinions on this subject. I reviewed the power curve in the Rotax manual and based on the different power setting it could handle the amperage that I am looking for. Thanks and look forward to hearing from some experienced pilots out there. I am building a Breezer made in Germany and I am working on putting my panel together.
User avatar
drseti
Posts: 7227
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: Can a Rotax 912 100hp handle these amps?

Post by drseti »

For anything more than basic avionics, you really need to use an accessory generator on the Rotax 912ULS. There is an accessory housing on the back of the gearbox for this purpose, and Rotax sells a mounting kit with the appropriate shaft, gear, bearing, and seal. The 15 amp accessory generator used by most SLSA manufacturers does the trick, but remember that the extra electrical load will cost you 1/3 HP (15A x 14V / 746 W/HP).
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
[email protected]
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US
roger lee
Posts: 807
Joined: Tue Dec 08, 2009 11:47 am
Location: Tucson, Az. Ryan Airfield (KRYN)

Re: Can a Rotax 912 100hp handle these amps?

Post by roger lee »

"Can a Rotax 912 100hp handle these amps"
"TOTAL Amperage: 20.26 (Rotax internal alternator only)"

The short answer is no.

The internal amp output is advertised at 20 amps, but continuous is 16 amps and peak should be no more than 18. You do need aux gen. You also need to consider the reg/rec as trying to pull too much load will cause excessive heat.

Keep the amp load to 16 or less and you're okay.

When everyone wants more in their planes as it has been over the last 11 years with LSA that does come with a price eventually.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)
User avatar
drseti
Posts: 7227
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: Can a Rotax 912 100hp handle these amps?

Post by drseti »

We had an extensive discussion of this very topic two and a half years ago. Here's the thread:

http://sportpilottalk.com/viewtopic.php?f=19&t=3004
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
[email protected]
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US
Wm.Ince
Posts: 1080
Joined: Sun Nov 17, 2013 3:27 pm
Location: Clearwater, FL

Re: Can a Rotax 912 100hp handle these amps?

Post by Wm.Ince »

drseti wrote:We had an extensive discussion of this very topic two and a half years ago. Here's the thread:
http://sportpilottalk.com/viewtopic.php?f=19&t=3004
In my case, that brought up a blank web page.
Bill Ince
LSRI
Retired Heavy Equipment Operator
SportPilot
Posts: 1060
Joined: Mon Aug 25, 2014 3:39 pm

Re: Can a Rotax 912 100hp handle these amps?

Post by SportPilot »

.......
Last edited by SportPilot on Sun Mar 20, 2016 7:27 pm, edited 1 time in total.
Wm.Ince
Posts: 1080
Joined: Sun Nov 17, 2013 3:27 pm
Location: Clearwater, FL

Re: Can a Rotax 912 100hp handle these amps?

Post by Wm.Ince »

SportPilot wrote:Just click on it. It works.
Nope.
Still brings up a blank SportPilot Talk empty page.
Maybe it's because I have previously viewed the page in the past.
Bill Ince
LSRI
Retired Heavy Equipment Operator
User avatar
drseti
Posts: 7227
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: Can a Rotax 912 100hp handle these amps?

Post by drseti »

Make sure you're logged in to Sportpilottalk.com, and then try the link.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
[email protected]
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US
Post Reply