http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/ http://www.bandc.biz/alternator20ampshomebuilt.aspx
LR3C (9oz):
http://www.bandc.biz/alternatorcontrollerregulator14vhomebuilt.aspx]]> en-us Gallery 2 RSS Module, version 1.1.8 Sun, 10 May 2026 18:56:15 +0000 120 http://www.europaowners.org/gallery2/d/28327-8/album226.jpg http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/ http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/Alternator_failure_Richard_4.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/Alternator_failure_Richard_4.jpg.html
Failure on a Jab 3300 4
Update, a SD20S was installed, and too the spline stripped after a while. Upon the next repair a section of old spline was installed to make engagement of splines more with alternator. thus far ~ 100 hours plus with no problems.
Y9-06-07]]> rparigoris photo Tue, 17 Nov 2009 23:27:36 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/Alternator_failure_Richard_3.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/Alternator_failure_Richard_3.jpg.html
Failure on a Jab 3300 3]]> rparigoris photo Tue, 17 Nov 2009 23:27:36 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/Alternator_failure_Richard_2.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/Alternator_failure_Richard_2.jpg.html
Failure on a Jab 3300 2]]> rparigoris photo Tue, 17 Nov 2009 23:27:36 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/Alternator_failure_Richard_1.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/Alternator_failure_Richard_1.jpg.html
Failure on a Jab 3300 1

In all fairness Jabs female drive is aluminium, where Rotax is steel and I think Jab is harsher than Rotax on this drive. He went through at least 2 of these alternators. He said he purchased a SD20S and it stopped working, has not looked into as of Y7-10.]]> rparigoris photo Tue, 17 Nov 2009 23:27:36 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002140.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002140.jpg.html
Watch out brown rubber anti explosion/sparking seal is properly positioned or it will drag.]]> rparigoris photo Tue, 17 Nov 2009 23:27:36 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002139.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002139.jpg.html
B+C custom cast front case.

2/23/2010, you wrote:

>Hi Bob
>Thx. for the reply.
>">>Curiosity question, according to B+C a SD20S alternator turning when
> >>hot at 2500RPM it will produce 24 amps at 14V, how much approximate
> >>loss will there be using a LR3C regulator? How much approx. loss
> >>using a switcher?
> >>
> >>Same question for SD20S at 2000RPM, 15 amp output at 14V?"
>
>" "> No difference. The regulator's influence on max current
> > available is minimal. The alternators driven from a
> > vacuum pump pad are RPM limited. > " "
>
>I may not understand what you said, or I find what I think you said
>hard to believe. Are you saying that a LR3C creates no loss what so
>ever off the listed output of a SD20S on B+Cs spec sheet? Are you
>saying that a switcher is not more efficient than a linear
>regulator? I was hoping perhaps someone had actual measured losses.
>B+C never measured a switcher, but thinks perhaps LR3C will incur a
>1.5 amp loss (the more amps, the more loss) not more than 2 amps in
>my scenario.

Not sure what you're calling "losses". The controlling
device in a plain-vanilla duty-cycle controlled regulator does
not get as hot as the linear device. However, just because a
linear tosses off heat (maximum when the field voltage is
1/2 of bus voltage) doesn't mean that there's more energy
available from the alternator.

Minimum speed for regulation, minimum speed for full output
and maximum output are measured under conditions that the
regulator is turned on max-hard. In both styles this is
100% duty cycle output with the field voltage being only
a tad below bus voltage.

The drop in a max-on linear vs. a max-on switching
regulators might be a bit different . . . but both
are on the order of 1 volt. In a belt driven alternator
running nearly 10,000 rpm, this is an insignificant
drop that does not limit the alternator's ability
to deliver max rated power.

When you're RPM limited, then it MAY be that one
regulator may produce a tad more output. You'd
have to do a side-by-side bench test or have
access to the alternator's transfer function curves
for the RPM of interest.

In any case, the differences are small and mostly
academic . . . if ones successful termination of
flight in the endurance mode hinges on the availability
of just a tad more alternator output, the load
analysis for that condition needs to be re-evaluated.

Keep in mind too that field current supplied through
the regulator comes from the bus and is probably
on the order of 2.5 amps. This is PART of your running
load. So energy available to run the elecro-whizzies
is taxed by the value of field supply current.

For internally regulated alternators, rated output
is over and above field supply requirements. But
for the SD-20 in an RPM limited mode, the field
current comes off the top of what ever the total
output of the alternator happens to be. A switching
regulator of any style cannot improve upon that.

Bob . . .]]> rparigoris photo Wed, 24 Feb 2010 05:07:34 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002138.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002138.jpg.html
SD20S driven.]]> rparigoris photo Tue, 17 Nov 2009 23:27:36 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002137.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002137.jpg.html
SD20S drive. The black shaft is the male spline that takes power from motor female spline.]]> rparigoris photo Tue, 17 Nov 2009 23:27:36 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002136.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002136.jpg.html
Absolute jewel, B+C SD20S with beautiful shock absorbing drive ripped off from vacuum pump. Using a B+C LR3C linear regulator with adjustabel setpoint and OVP. "NOT CHEAP" but IMHO worth every cent. Output on both identical when heat soaked, but linear regulator eats a little current compared to internal switcher. Can count on 18 amps realistic when heat soaked, and unrealistic 60 amps when dead cold for only moments. Thx. Bill at B+C for testing!
914 gear ratios:
Accessory pad 1 revolution for 1.842 crankshaft revolutions (.54 of crank)
Prop shaft 1 revolution for 2.43 crankshaft revolutions (.41 of crank)

(ALTERNATOR RPM) - (HOT OUTPUT (14V) AMPS) - (ROTAX CRANK RPM)
2,000 RPM 15 AMPS 3,684 RPM
2,500 RPM 24 AMPS 4,605 RPM
3,000 RPM 29 AMPS 5,526 RPM
3,500 RPM 32 AMPS 6,447 RPM
Need to take losses of LR3C off above.

Note for a while B+C SD20 and SD20S got a bad reputation for a low output. First off Bill tests when they get hot, which provides a more useful and realistic number. Then he made a mistake! He was touting output for 28 volts and had it marked as 14 volts!
Here is 28V output for alternator RPM
2,000 RPM 0 AMPS
2,500 RPM 4 AMPS
3,000 RPM 12 AMPS
3,500 RPM 20 AMPS

Bill never measured losses of a switcher, but said a switcher is more efficient, thus has less loss than a LR3C, albeit with much more noise than the linear LR3C. When asked of approximate loss off published SD20S output, said he never really measured but said the more amps you output the more loss. When I pushed for an approximate loss at 15 amps, 20 amps and 25 amps, he thought perhaps 1.5 amps, but probably never more than 2 amps.

He notes on LR3C warning light, make sure you can read whatever you select in bright sunlight and viewing angle catches your eye. said 500 ohm resistor in series allows use of LEd without it glowing when off.
Y10-02-22]]> rparigoris photo Tue, 23 Feb 2010 21:18:56 +0000 http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002135.jpg.html http://www.europaowners.org/gallery2/v/Begin-06-2003/album258/album226/IM002135.jpg.html
I owned a 1987 Suzuki Samari. One of my favorite things was compact ND alternator it had. ]]> rparigoris photo Tue, 17 Nov 2009 23:27:36 +0000