Alternator STC

How to keep the Cessna 170 flying and airworthy.

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jcsand
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Alternator STC

Post by jcsand »

Considering replacing the generator on my '55 170B with an alternator. Looking for recommendations from those who have done this. Which package/STC is the best for our airplane? Thanks.
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GAHorn
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Re: Alternator STC

Post by GAHorn »

If you have a 35A generator… I’ll buy it from you when you do the conversion if it’s in working condition. (regulator also)

Why..? Because I have a 172 with the Jasco alternator which I plan to remove and give to the Assoc’n and return the airplane to a generator. (Yep….I prefer generators to alternators in this particular application.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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Hawkeyenfo
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Re: Alternator STC

Post by Hawkeyenfo »

George, I feel the same....never had an issue with my generator ....other than a bit of a persistent leak from a grooved shaft.

Chris
Fly Navy !!!!

1941 Boeing PT-13D Stearman
1952 Cessna 170B
1960 Piper Aztec (PA23-250)
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Ryan Smith
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Re: Alternator STC

Post by Ryan Smith »

I’ve done the Plane Power on my 170 and my Bonanza. Big fan.

I differ from George on the generator versus alternator sentiment, but it is nice to not have to add external power if you have a completely dead battery.
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Vertical
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Re: Alternator STC

Post by Vertical »

BC433-H with STC.
ER14-50
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pdb
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Re: Alternator STC

Post by pdb »

I have the Plane Power alternator and am pleased with the output and weight savings.

I did leave the master on once when I had the generator and ran the battery down. However I was able to hand prop it and use the electrics and the radios on the way home. That stunt and the subsequent high initial charge rate probably took some expected life off of my battery.

If I had had an alternator then, I would have gone home dark and NRDO. Not a huge problem during the day.

But does anyone know how big a battery, how many volts, and for how long would I need to apply a charge to the dead battery to get the alternator energized?
Pete Brown
Anchorage, Alaska
N4563C 1953 170B
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jcsand
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Re: Alternator STC

Post by jcsand »

Thanks to all for your thoughts. My generator has never given me any problems. Some owners have said that they like the fact that an alternator comes online quicker than a generator.
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Bruce Fenstermacher
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Re: Alternator STC

Post by Bruce Fenstermacher »

Pete, I'd have to believe if you carried at small sealed lead acid battery with the appropriate connectors to temporarily plug in to excite the alternator, that would work.
Screen Shot 2022-11-19 at 11.04.21 AM.png
2 of these batteries are used in series for 24v as the second battery in every Cirrus flying. I understand they could run the Cirrus glass cockpit for at least 15 minutes maybe more, I've never cared about a Cirrus enough to find out.

Without looking at the 170 schematic, an interesting idea might be to back feed the system through your cigar lighter long enough to excite the alternator or with the master off even just run your radios till you get home.

Not having an electrical system in my Vagabond I have one of these running my handheld, intercom, IPhone, and occasionally a ADSB-in . I've run one without charging it for at least 6 hours this way.

These are about $25 bucks at hardware stores and I've had them last for several years. I get them for free and currently have 10 in my garage removed in the last 2 weeks from Cirrus aircraft as they are removed every 2 years from service in them by most Cirrus owners. Unfortunately there are no Cirrus Service Centers in Alaska, you could probably get one cheap off their pile of removed batteries and try it. They and smaller versions are also used in emergency lights over doors and they are replaced periodically in that application but still good.
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hilltop170
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Re: Alternator STC

Post by hilltop170 »

Thanks for bringing up the portable battery option for a dead battery and alternator situation.

I have asked every person I know that understands these systems better than me how much voltage and power does it take to excite an alternator? Nobody so far can even make a good guess.

And it hasn't been a high enough priority for me to run an exercise to find out.

My thought is a 9v transistor radio battery plugged into the cigarette lighter should do it assuming the lighter is wired direct and not thru the master switch relay.

Anybody care to take a guess if that will work?
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
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Ryan Smith
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Re: Alternator STC

Post by Ryan Smith »

hilltop170 wrote:Thanks for bringing up the portable battery option for a dead battery and alternator situation.

I have asked every person I know that understands these systems better than me how much voltage and power does it take to excite an alternator? Nobody so far can even make a good guess.

And it hasn't been a high enough priority for me to run an exercise to find out.

My thought is a 9v transistor radio battery plugged into the cigarette lighter should do it assuming the lighter is wired direct and not thru the master switch relay.

Anybody care to take a guess if that will work?
.4 volt is what I’ve always been aware of. Can confirm.

9v battery is well more than sufficient.
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GAHorn
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Re: Alternator STC

Post by GAHorn »

Richard points out the problem which Bruce’s suggestion did not address….

I have a small cigar-lighter plug with a pigtail to a “snap” connector for a 9-V battery. It was sold as a “keep alive” circuit for when mechanics change-out a battery on an automobile so that the entertainment system doesn’t lose its’ memory of radio-channels, or the environmental system its’ temperture settings, keep the engine ECU memory alive so it doesn’t have to “re-learn” your driving habits, etc.

It would definitely suffice to “wake up” an alternator …IF…. IF you could get the cigar-lighter in your cockpit ON-LINE…which you cannot because the battery-Master Solenoid will not close to put the main buss online with the alternator field.

The FIX as Richard points out would be to “hot wire” your cigar lighter to the main buss instead of thru the Master Solenoid. The problem with THAT is whatever iPad charger or other device you have plugged into the cigar-lighter will likely DEPLETE your battery DESPITE if you remembered to turn your Master Switch Off. :? In other words, you’ll increase the likelihood of depleting your battery by accident.

The best thing to do is turn your strobe lights ON and Leave them ON… so you cannot walk away from your airplane without noticing the flashing strobes.

AS for the generator versus alternator choice, here’s my opinion:

The generator does not put out meaningful voltage at low engine RPM…(below 1200)…and that bothers a lot of people to imagine their battery is being harmed by not constantly seeing a “charge” rate when it’s online. That is INCORRECT thinking, in my view. In-fact, a battery seeing regular use in discharge/recharge cycles is GOOD for the battery (and especially so for some exotic types.)

Some folks worry that their battery discharges too-far during long taxi-periods before takeoff if the land/taxi lights are “on”. But, the upcoming engine-RPM for take-off and climb-out is going to rapidly re-charge that battery. No problem.

Next, …while flying around IN the “Pattern” low RPM is frequent….(very little of which is actually below 1200-1400, the “coming-in speed of a generator)…. So What? Half, or more, of that pattern is at high or medium engine RPM ….and The next take-off is going to take care of that as well.

Keep in mind a battery is primarily a source of electrical power in the event of no or low generator/alternator output. That IS what it is for. Be happy. Let that happen.

But…some folks say… their battery is on its’ last-legs and they need to keep it charged-up…. IN THAT CASE go ahead and bite the bullet and buy a new battery! Remember, a battery is an emergency source of stored electricity… IF your battery is “old”…then your MAJOR PROBLEM will be if that alternator QUITS…especially at night. It’s poor planning and practice to continue to operate with a battery that should be retired.

Batteries are not for starting engines. They are stored emergency electricity. The fact they can start our engine is a Great Test of pre-flight activity. But the Next preflight check (after oil pressure) should be that after start/during taxi and Run-Up that the battery is being Re-charged Only then is the electrical system known to be airworthy.

Also, modern avionics are solid state and do not require the huge electrical demands of old vacuum-tube stuff. Modern LED lighting, (nav/land/taxi) also don’t need huge power. I have replaced my Land/Taxi and Nav and interior instrument/cabin lighting ALL are L.E.D.

Yes, my 35A generator allows a (now insignificant) discharge during long taxis at night. No Problem.

PRO ALTERNATOR thoughts are: Save some weight …about 11-14 lbs… But it is Forward of the Firewall and most airplanes gain weight as they age AFT of the firewall. This may actually hurt your ability to stay within C.G., especially for use in the Utility-Category (another good reason not to Spin these old airframes unless a thorough inspection and recent actual re-weigh has been performed.)

Finally, The Alternator conversion will cost you about $1500 plus labor. Some of them (Jasco) is so proprietary that you cannot obtain repair-parts and must either send it back to the mfr’….or perform another complete STC installation. A generator overhaul is about $200.

IF I were to convert my 170 to an alternator I would not use any of the aftermarket STC’d versons…. I’d do it using the genuine Cessna Service Bulletin using the systems Cessna used in later 150 and 172 aircraft. That’s just my personal feelings about it. Hope it helps.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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wabuchanan
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Re: Alternator STC

Post by wabuchanan »

When I bought my plane, one of the previous owners had already done the Great Planes alternator STC.

I have found it to be a great product. Smaller than I believe the Jasco unit, has been reliable with no problems encountered. If you are going to do the changeover to alternator I think it would be a great choice for you.

One of the truly nice things about having Piano switches, is not leaving the Master on. Just a quick glance at the switches confirms all are off. If any doubts, just run your hand under them. I've never left it on since buying the plane.
1950 170A N5776C SN:19730
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n2582d
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Re: Alternator STC

Post by n2582d »

My plane has a Ford alternator installed with a field approval using an early C-172 wiring diagram as an example that was duplicated. This was back when field approvals were relatively easy to come by. If you decide to use SK 172-22M make sure you've got FAA approval before commencing with the conversion. Does anybody know if Barnstormer Aviation SA00202NY is still available? It was discussed here years ago. Having an STC such as this would save a lot of hassle over trying the field approval route. But if you do go the FA route, Neil Wright of the Cessna 120-140 Association has an excellent write up on things to consider when doing such a conversion. You'll find that article here. If you don't need 60 amps or all that weight I'd be tempted to go with B&C's alternator but realize you may need a new drive gear which could be pricey. I also see that on B&C's website these alternators are "out of stock".
Gary
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Bruce Fenstermacher
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Re: Alternator STC

Post by Bruce Fenstermacher »

wabuchanan wrote:One of the truly nice things about having Piano switches, is not leaving the Master on. Just a quick glance at the switches confirms all are off. If any doubts, just run your hand under them. I've never left it on since buying the plane.
There are those with piano keys that have never left the master on and there are those that haven't yet done so. I'm in the later camp and I have good company.
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lowNslow
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Re: Alternator STC

Post by lowNslow »

n2582d wrote:My plane has a Ford alternator installed with a field approval using an early C-172 wiring diagram as an example that was duplicated. This was back when field approvals were relatively easy to come by. If you decide to use SK 172-22M make sure you've got FAA approval before commencing with the conversion. Does anybody know if Barnstormer Aviation SA00202NY is still available? It was discussed here years ago. Having an STC such as this would save a lot of hassle over trying the field approval route. But if you do go the FA route, Neil Wright of the Cessna 120-140 Association has an excellent write up on things to consider when doing such a conversion. You'll find that article here. If you don't need 60 amps or all that weight I'd be tempted to go with B&C's alternator but realize you may need a new drive gear which could be pricey. I also see that on B&C's website these alternators are "out of stock".
When I bought my 170 in 1992 it had the Ford alternator installed. It did not have any paper work for the installation so I bought the Barnstormer STC for $75, this was in 1999. I don't know it they are still around.
Karl
'53 170B N3158B SN:25400
ASW-20BL
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