Q. Gear Drive Alternator installation on Vacuum drive

[Bcone1381]

I am thinking and researching the Alternator choice for my QB Patrol kit. It will have an IO-360 that has a vacuum pad provision on the accessory case. I am thinking about installing the B&C Specialty Products gear driven alternator ( http://www.bandc.aero/pdfs/quickfacts_bc410-h.pdf ) on that drive and wondering if anyone else has installed this unit one theirs. Specifically, how has it worked out, and is there enough space between the accessory case and firewall to accommodate this unit..

[Bdflies]

Yes! I'm running a BC410 on my O-360 A1A. I think it's great! I'll admit to some initial concerns about the relatively limited output (20-30 amps), but found it's a complete non issue. Modern avionics and LED lighting draw very little current. The most load I've ever seen is 14 amps, after fumbling the engine start and running the battery down a bit. Normal load at cruise is 7 or 8 amps. The alternator is small, there's no belt to monitor or replace and there's no bracketry to inspect for cracks and adjust. I also have the B&C oil filter adapter. Nice piece of equipment. It's kinda snug up at the top of the accessory drive, but it all works fine. Firewall clearance is no problem.

Bill

[JimParker256]

Good to hear, Bill. That's what I am planning to do as well. Seems like a neat, clean, lightweight solution.

[svyolo]

On VAF in the electrical section there is an "alternator reliability poll". Good reading.

[svyolo]

The only issue with the gear driven alternators is they run at very low rpm. On the ground with the engine running, you will probably be draining your battery. As long as your loads are light, no problem. It sounds like a lot of folks use them as backup alternators, but with light loads they do fine as a primary as well.

[Bdflies]

I can report that SV's comment has some validity. I have the alert level of my G3X set to 12.5 volts. Below about 1,000 rpm I'll see the buss voltage turn red, dipping to 12.3 or so. Idle above 1,000 rpm and all is good. My PC680 battery shows about 12.1 at rest, which sounds REALLY low to me, but it spins the Lycoming just fine. I think my PC680 was purchased in June 2015. Having no past experience with such batteries, I'm paying close attention to it. Even at 12.3 volts, the battery isn't discharging, it's simply below the warning threshold I've set in the system.
So, yes, it's my observation that the geared alternator doesn't have the same output at idle as belt driven units. Now that I think of it, though, the Low Voltage light, in my Husky, would illuminate at low idle. Hmm...

Bill

[Bcone1381]

I have been some reading Bob Nuckolls AeroElectric Connection recently. He says this type of alternator has been adapted for use on the vacuum pad with the spline drive with stellar results. It has bearings rated for the side load and high RPM's and high electrical output of a belt drive. He says we should see some outstanding service life with this unit because the reduced side loads, low RPM, and low electrical loading.

FIREWALL: My goal will be to mount the battery on the engine side of the firewall. Are you guys having any trouble finding space for it on the firewall, or are you mounting them someplace else for another reason?

[Bdflies]

Brooks, my idea of planning the firewall begins with placing the stuff that is 'location mandatory', like control cable pass throughs, large electrical wires and fuel lines. Then, locate the most convenient places for the biggest items, like oil cooler and battery (if that's where you're going to put it). Last, the small stuff, like sensor, starter and P-lead wires. My battery is under my seat, because the original builder had provided for it. There's room on the firewall. It'll get tight though.
I found a good pic showing the alternator clearance.

Bill

[svyolo]

B&C claims that belt driven alternators are more reliable than gear driven ones. I emailed them several times with questions, and they were very upfront with their info. I wasn't expecting that. Good on 'em.

[Bcone1381]

Thanks! I will contact them.

[tf104]

Brooks, my idea of planning the firewall begins with placing the stuff that is 'location mandatory', like control cable pass throughs, large electrical wires and fuel lines. Then, locate the most convenient places for the biggest items, like oil cooler and battery (if that's where you're going to put it). Last, the small stuff, like sensor, starter and P-lead wires. My battery is under my seat, because the original builder had provided for it. There's room on the firewall. It'll get tight though.
I found a good pic showing the alternator clearance.

Bill

Thank you for posting the photo can you tell me where the cable pass-throughs can be purchased?

[rv8bldr]

Thank you for posting the photo can you tell me where the cable pass-throughs can be purchased?

I bought mine from Van's Aircraft. They have lots of great stuff and you don't need to be building an RV to buy from them. Their prices are normally as good or better than anyone else.

Cheers

Mark

[Bdflies]

Thank you for posting the photo can you tell me where the cable pass-throughs can be purchased?

The picture shows the control cable 'eye ball' pass throughs, that I got from Aircraft Spruce. P/N 05-01384
Also pictured are penetrations for battery and sensor wires. Also from Spruce. P/N 09-00978

I'm lazy. I've grown so used to ordering from Spruce, I only look elsewhere when they don't have something. I have to admit, though, my experience with Vans is excellent as well! The eye ball units are great and they look good. The penetration kits for the wires are (in my opinion) a brilliant solution to a tricky problem.

Bill

[JimParker256]

Instead of the aluminum eyeball firewall fitting (ACS P/N 05-01384) that Bill referenced, I would suggest using stainless steel eyeball fitting (ACS P/N 05-01382) for those control cable pass-through penetrations. I say that because Bill says he used ACS P/N 09-00978 for battery and sensor wire penetrations, and in their writeup about that "stainless steel firewall penetration kit" for wiring, ACS says that when they tested the aluminum fittings, they melted away in only 16 seconds...

(I suspect Bill is actually using the SS versions of the eyeball fittings as well, and only posted the AL part number because they look pretty identical in the pictures, and the AL ones are listed first on the ACS site.)

[Bdflies]

No Jim, I used the part #'s that I referenced. The eyeballs are aluminum, not stainless. You're right that such units made of stainless steel would offer significantly more heat protection.

Bill

[tf104]

Thank you so much they sure look like an elegant solution, the comments about stainless vs aluminum makes me wonder about the aluminum heat box I got from vans.

[Archer39J]

I recall seeing a tip about using oversized hardware, bolt and nut, and drilling a hole through the center as a pass through. I can't quote part numbers but it seemed like a simple and cheap solution for wires at least. Don't know about control cables.

[jaredyates]

That works pretty well as long as your controls are passing through perpendicular to the firewall. I used drilled bolts for bowden cables on carb heat, cabin heat, etc. The eyeballs are nice when you want to pass through the firewall at an angle.