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dual alternators

D

doctornigel

Active Member
Who has or is planning dual alternators? I would like to have an engine driven airconditioner compressor as well. Does this limit me to a vacuum pad alternator (SD 8 or 20) and will they work with an IO-540? Thanks.
 
Which AC unit?

I plan on installing dual alternators and the FlightLine AC unit. FlightLine's installation swaps the AC compressor with the current alternator position, moving the alternator onto a new bracket mounted on the other (pilot) side of the front of the engine. Both are run by belts off the flywheel. All parts included in the kit.

At least that's my understanding of it so far (just getting into it). Can't speak to any other AC installations.

Dwight
 
We've been working with Flightline AC while developing our air conditioning controller. If you want an engine driven compressor (which most RV folks get), then the accessory pad on the back of the engine is unaffected. You can install an 8-amp or 20A alternator there, in addition to one up front. You can get by with a 12v system and a large primary alternator, but will definitely need a 24v system if you want to use an electric compressor.
 
Dwight,
I believe with the flight line AC you will need to use a B&C alt. up front and also the B&C starter because the plane power alt. and SkyTec starter will not fit in that application.
 
flightline AC

raddatz said:
Dwight,
I believe with the flight line AC you will need to use a B&C alt. up front and also the B&C starter because the plane power alt. and SkyTec starter will not fit in that application.
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I sure hope that is not true. I will be hanging the engine in the next few days and have the Plane Power alternator. I do have the B&C starter. I guess I will know soon.
 
Hmmm...

Hadn't seen or heard that, I'd be interested in hearing the results from David... haven't bought my engine yet (but soon).

Dwight
 
Afraid it is true. The Plane Power Alternator will not fit on the bracket supplied with the FlightlineAC engine driven alternator kit. We tried it today. I talked to John Strain at FlightlineAC and he confirmed that they had just learned this within the past couple of weeks.
I have to say, Aircraft Spruce is great to deal with. They are taking the Plane Power back and will credit my account. And, of course, they were happy to sell me the expensive, but excellent, B&C 60 amp alternator that will arrive the day after tomorrow. :rolleyes:
Spruce has been absolutely wonderful to deal with during this project.
 
Dual Aalternators......One should do you.

Too much weight and twice the risk of one failing.

Design your electrics well, two batteries, and why worry. If the ALT fails you have plenty of battery time and more if you shed loads properly. Possibly more battery time than you have fuel reserves!

DB
 
I had two alternators on my old Rocket. On this one, I am going with dual batteries and one alternator. My reasons are cheaper, simpler, same redundancy .
 
Same redundency? Does anyone load test their batteries every 6 months? If you don't then you have no idea of it's ability to carry your electronics, it may start your engine, but your 22 a.h. battery may only be half of that capacity when you need it. And the 22a.h. rating doesn't mean you can keep 22amps going for an hour, those ratings are usually done more like 4.4 amps per 5 hours, and that's a fresh battery. A fresh 22a.h. is more like maybe 10amps the first hour and then way down from there, and that's a fresh battery. So say you have two, that's way better than just one, but unless you have two fresh ones, you really have no idea how long you have. But if you replace the main every year and rotate the old main to the standby, you are probably never going to be in trouble. I am opting for an SD20 in the standby vacuum pad mounting and dual batteries, but my second one is going to be a small and not placed in the back. I have a really power hungry panel planned and with my setup, I won't have to shed any loads. My weight penalty will be minimum, and my cost will only be a few hundred more for the SD20.
 
My last airplane was a Mooney 231 with a Rocket 305 conversion (TSIO 520 NB) To balance the greater weight of the larger engine they put 2 batteries in the tail cone. While IFR out of Jackson hole above the weather at 14,000'+ my alternator died. The auto pilot was voltage sensitive and quit. The rest of the radios were fine and after shedding what I could I had no real concern about contiuing to the next VFR airport along my route. It would have been nice to have a back up alt. The SD20 alternator spoken of above weighs 6 lbs. and costs $695 from Aircraft Spruce.
 
Welcome!!!!!!

Hey Randy, welcome to the good ship VAF:D

Glad to have you aboard.

You have my condolences about the Morris Garage artifacts:eek:, I got cured long ago.
 
doctornigel said:
Same redundency?
Click to expand...

Yep, for my purposes it does. I think you are a little optomistic on the cost side of things when you consider the alternator, alternator controller, wiring, indicator lights, switches, etc, but that's okay. If it works for you then go for it. I did it that way once myself.

With dual batteries, I can do just about anything I could have done with dual alternators. If my primary alternator quit, I would continue on to my destination. If my primary battery quits, I would continue on to my destination. Of course this assumes you maintain your batteries, just as dual alternators assume you maintain them as well. How many people change out their alternator belt on a regular basis? Probably fewer than those who change out their batteries.

In the end, both offer positives and negatives. Use whichever one floats your boat.
 
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