I want to not have to be discretionary in my use of electricity and with the 914 having electric fuel pumps I reckon it might be smart to consider a 2nd alternator. I believe there is a blank up front on the crankcase for one.....I would like to hear from anyone who has first person experience with using one please? 

Thanks in anticipation.

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Would it not be a lot simpler and cheaper to just have a dual battery system with the 2nd battery isolated from the primary battery so that in the event of an alternator or primary battery failure, you'll have reserve power until you can safely land?



I think the issue is more that the 914 only provides 8-14A of usable power for accessories and non-critical loads (from what I'm reading here). A second battery won't help with that if one is trying to pull 20A, which isn't hard these days.

Sorry if I'm misunderstanding the topic.

Sorry if I'm misunderstanding the topic.

I think I misunderstood the topic more than you! LOL!  However, it does seem the trend in modern avionics and lighting is that amp demands are going down what with LED's, etc.


Pitot heat usually pulls 10 amps.

Ouch.....Do you have a heated pitot John? If so, have you ever flown in cloud, or just a quick transit through a layer or two, and put it on for that?

It is the heat that pulls the amps, I believe all heated pitot tubes are about that. I haven't gotten to my wings yet, but there's always the chance of some ice anytime flying though a cloud below freezing. It doesn't take much to make a pitot tube inaccurate, I would not fly IFR without a heated pitot tube even if you are not intending to fly in icing. VFR only not an issue.

10 amps is a lot. Agreed re icing, never had to think about it too much, always had heated pitot, but 10 amps plus electric fuel pumps on the 914 doesn’t leave a lot spare, you’d be chewing into the battery for sure. I need to find a 914 owner who is flying, if anyone knows one…?

I'm a bit late to the party but here is my build with a 914.  Many things take less power than it would first appear.  For example a Trig radio requires a 5 amp breaker but only pull about 1/2 amp continuous.  The fuel pumps are listed below as well.  As you can see my build came up with some room to spare.  The tablet chargers are still a bit of a question on what they'll draw continuously.

18 amps availab
ACK 406/121.5 MHZ E-04 ELT Just a wild guess.
Trig ty 91 radio w/ harness .2A continuous 2A when transmitting
Trig tt22 transponder w/ harness
Trig tn72 gps position source
iLevil AP, just a guess, calls for a 3A breaker
GRT engine monitor
2 chargers for small tablets
2 small pc fans for cooling tablets, combined <1A
1 heater fan .3A (heater fan and cooling fans won't be run at same time)
Aero LED nav/strobe/pos
Aero LED landing light
12v Aux for phone charging etc
2 rotax fuel pumps page 14. 1.7A/ea if individual. 1.5A/ea if running both.
electric elevator trim tab 2A breaker on friends plane
electric flap actuator 5A breaker on friends plane

Hey Jasper,

That's a detailed list and I didn't know you'd posted it to this discussion, thanks for that. I'll go over it more thoroughly as I get to that part of the build, hopefully not too far away. I am gathering you have a single alternator only at this stage? 


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