More than 70 amps
tx_jayhawk said:
Does anyone know of a source for an alternator bigger than 60 amps that will fit in the stock RV7 cowl? I know Plane Power makes a 70 amp (its also sold through Spruce and Chief), but I understand it would require a bulge in the cowling. B&C and Vans are obviously not available.
Thanks,
Scott
7A Finishing
Yes there are some 110-130 amp alternators, and yes they are bigger. They also weight twice as much. Can I ask do you really need more than 70 amps? If yes than what is the big draw?
I can point you to some alternators that will work. As far as bulge? I think you can get fit it without a bulge, which is usually associated with the pulley. You have to fit the bracket, tension arm and belt so the alternator is absolutly as tight to the engine as possible.
There are medium frame ND's that will do 90 amps that fit (see link below). It is no surprise the size/weight of the alternator is really a function of max output. You need bigger stators and rotors to produce more amps. Another way of saying it is you need more weight to produce more amps.
ND alternators
20-55 amps small frame 6 lbs
60-90 amps med frame 8-9 lbs
90-130 amps large frame +13 lbs
Here is a suggested link:
http://www.miramarcollege.net/programs/avim/faculty/north/alternator/index.htm
He claims 60 amps which is correct for continuous duty. It actually has a higher absolute rating. I agree 100% with de-rating and not running at rated power, which is a sure way to fry it in short order. My RV-7 is only about 10 amps day, 20 amps night and 32 amps max with everything on (not continuous).
Just consider the weight, double check your numbers and consider not installing the heated seats, microwave and coffee maker.
