What is the net output of Rotax's internal generator?

Hi Kenz

Go and download the latest istallation manual, all the data is in that book.

Just a summary.  You have an 250 watt stator.  Watts divided by regulator volts will give you about a maximum of 18 Amps.  Using AC 43.13 current issue as a guide you should not consume more that 80% of your max power.  Round that out and you have about 14 amps useable.  When you total up 2 fuel pumps, lamps for the warning lights, servo motor and other required electrical to run the engine there is about 8 amps gone of 14.....so you have an issue when you start to add in your instrument panel and the worst draw is normally lights.  (I suggest use only LED type, especially for strobes)  Stay away from general aviation strobes like those nice triple flash ones on a Cessna or Piper...they can run 7+ amps themselves.  Size your battery large enough to run things for up to at least 30 minutes if you fail say a regulator.  

In the installation manual they also suggest you consider an accessory alternator, the Rotax one has some 45 amps.  This solves the electrical draw but adds weight and complexity for your wiring.  And unless you actually need it don't run a landing light....you will be pulling from the battery and we don't want to lose a fuel pump due to electrical load being too much.

Cheers

Awesome!

Follow-up question: how did you know to look there? I am a little confused by what I find in the user manual vs. the line manual vs the heavy maintenance manual vs the installation manual. I inevitably do a CTRL-F in the wrong one and never seem to find what I'm looking for. Then I come here and do a quick forum search and find it right right away.

Hi again Kenz

Just a lot of experience.  My first visit to the factory to look at the aircraft version engines was in 1988.  When you are looking at an installation of the engine into any aircraft the IM is the manual to use.  Electrical loads are good to know.  As for the type 914 in the early 1990s there was a lot of development on that design.  

Here is the list..

IM, all installation info, OM, operators manual, all the operational limits and data for flight requirements., MML,, line maintenance covers anything with inspections up to annual.  It may refer you to the MMH, heavy manual, for some items.  MMH, heavy, deep repair of all components up to splitting of the crankcase.  Not included in the manuals are the overload clutch settings, splitting of the crankcase or cylinder valve seat rework.  

Cheers

Everyone with a Rotax engine should download all the manuals applicable to their engine. Read through them so when an issue pops up you'll  have some idea where to look it up. ALL ANNUALS should have the maint. checklist at hand so it can be followed and things not missed. I guarantee that mechanics that don't  use the checklist miss things. This will cause bad trends being missed and open the door for engine issues including complete failures.

I personally print a Rotax annual / 100 hr checklist for evey inspection, I fill it out, sign off everything done and annotate anything I touch, tweak, torque or change in the margins and then this is given to the owner. I do the same for the fuselage part too.

My quote:

Don't strive to be average, strive to be a cut above! 

I do exactly the same Roger. I was wondering if I am overkilling it, but glad to hear from a pro like you.