I'm building my Cruzer with the following electrical loads and their "assumed" amperage draws. I've rounded.

Garmin 327 xpndr: 1 amp typical 1.7 max

GRT Sport EX: 1.5 amp

GRT EIS: ~1 amp

Skyfix / uAvionics GRT bundle: unknown; only says 11-33 volts DC; I'll say 1 amp

AeroLEDs: 1 amp ea, 2 total

iCom 200 comm:  2.6 amp

Total: about 9 amps total; in reality the AeroLEDs will be off most of the time.

Which got me to wondering: Do I *need* a 30 amp alternator? I can get a B&C 12 amp, the 200B, and still use my existing gear drive from my old alternator. I have an O-200, and if you use a bigger alternator, the gear has to be replaced due to fragging. So, with the gear and all, the 30 amp alt from B&X runs about $1000, whereas the 200B is $545.


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I have the B & C 12 amp on my O-200.  I only fly day VFR but do have lights if I come home at twilight.  I was a bit concerned that I wouldn't have enough power but weight was really important to me (and I also found a good deal on Ebay).  My plane is pretty light electrically equipped with a Dynon D-180, Aera 500 GPS, FlightLine 760 Com, Narco transponder, Uavionx Tail Beacon, LED landing, taxi and nav lights.  I do have the original incandescent strobes that came with the kit so I could save about 3 amp with LED's.  So with that setup and flying mostly daytime I really have no issues with the alternator not keeping up.  At idle, of course, it doesn't generate enough to keep up with the load but that is just during taxi, I usually see about 2-3 amp discharge during taxi.  After takeoff the battery is topped up to full voltage after about 15 minutes typically.  Also, the important stuff has onboard battery backup if something does go south.

I am sure I don't have much margin so you gotta keep an eye on it but for my plane it has been just fine.


Will the 12 amp alternator adequately recharge your battery(s) and power everything.  

We choose to leave our WigWag, Nav, and Strobes on in flight for maximum visibility, but then we also have a different engine, 40 amp alternator, and two batteries.

im running the 30 amp unit, after a start max current runs to "fill up" my earthx battery. running dual dynons, lights, radios, xponder, comm and gps. plus always on fuel pump and current for electronic ignition


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