Fred=2C
Sorry to confuse you. Volt Meters and Ammeters are best installed as charg
e meters=2C in my opinion=2C (alternator on the first post of the shunt and
the Battery input on the other). This is complicated by the EXP (or simpl
ified) by simply putting the ALT lead and Bat leads on the respective posts
. Of course the Control Vision Folks have a diagram on how we non pros sho
uld install the EXP for a Rotax. However=2C I find that the Rotax regulato
r tends to run high due to the PTC S2 terminal internal resistance. This d
rives the Regulator to increase voltage=2C if the voltage exceeds about 14.
5 then the OVP circuit kills the S2 power as the system senses an over-volt
.
I will try to send you some drawings of using the EXP with the Rotax. Then
an update to how I get them to run.
After installing 3 EXP busses I have noticed the following:
The EXP S2 to the field control of any normal automotive alternator like th
e B&C or Belt Driven types sold by Rotax=2C work flawlessly.
On the old style Ducati (with the green hard epoxy back) work well as insta
lled IAW the EXP install manual.
On the new style Ducati (with the rubbery black silicone back) tend to over
-volt for some reason if installed via the EXP manual. I don't know why!
I can't figure it out.
What the folks at Lockwood and I figured is if we hook the Ducati up with j
ust a short jumper wire from the B/R+ stud direct to the regulator=2C the E
XP and Rotax Ducati work OK together. However=2C you have no control over
your alternator function. If you still want the Alt Switch to function=2C
then run an 18 gauge wire from the R/B+ stud to the Alt Switch back to the
C of the regulator. The voltage drop of the #18 wire is only about .1 volt
s for the roughly six feet and doesn't drive the regulator way up. Or...Yo
u can use the short jumper and simply put a relay in line with the alternat
or output to the bus. To keep control and protection=2C power the relay vi
a S2 on the EXP to your alt switch and you are back in control=2C have OVP
protection=2C and the regulator is hooked up EXACTLY as Rotax desires.
As for the Volt and Amp readings from the EXP warning panel=2C they are les
s than accurate and very touchy. They are trend indications=2C and not acc
eptable for troubleshooting.
I prefer to use a separate Westach Volt/Amp meter using a shunt. This is a
very good gauge and fairly inexpensive. (The GRT EIS and Dynons both read
very well also=2C but both of these units measure voltage internal to the
unit and NOT the bus=2C therefore somewhat suspect for trouble shooting.)
On the Westach volt meter=2C I attach to my bus bar (or bat terminal of the
EXP). Then the ammeter is hooked to the shunt and the bat to the other si
de of the shunt (most shunts are labeled). What this does is read the tota
l amps being drawn from the battery to the bus when the regulator is shut o
ff or engine stopped. When the engine is running and the regulator is putt
ing out more voltage than the battery=2C then the ammeter is showing the am
ps which are going to the battery for charging=2C and when the regulator is
putting out less than the draw of the bus=2C the ammeter shows how much di
scharge my battery is providing to keep the overloaded bus load fed.
In flight the indications in the cockpit of alt/battery health are excellen
t. On ground ops=2C engine off=2C the volts read battery volts prior to st
art=2C after start=2C show instant battery charging. In flight should the
alternator fail=2C normally the regulator function in the Ducati fails and
you get no warning light. (The EXP "discharge shows and eventually=2C the
EXP "low voltage" warning comes on.) An EIS and Dynon can show the same an
d will do it to your particular settings. I like the Westach gauge as i
t shows instant readings on power up (no waiting for computers to boot) on
preflight. During start=2C it doesn't blank out=2C and more importantly sh
ows cranking volts (your indication that the battery is starting to go) and
inflight will show a discharge immediately and you note that the needles a
re even (zero amps to negative amps/12 volts or bat voltage) then they sag.
.. The Westach is faster=2C but the lectronic information systems give q
uicker warning. Either way=2C the units will give you excellent awareness
of your charging system health.
Bob Knuckles has the best description of the ways and type of hookups for t
he ammeter/voltmeter if you care to review more.
Hope this helps=2C
Regards=2C
Bud Yerly
> Date: Sun=2C 19 Jan 2014 17:24:30 +0000
> From: richard.holder@outlook.com
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Ammeters & Voltmeters
>
.com>
>
> > After reading Bud's post a few moments ago=2C I have a
> > couple of general questions about ammeters and
> > voltmeters which perhaps an expert can answer for me.
>
> > Up til now=2C I've planned to measure the voltage at the
> > plus side of the battery...Is that the best place to
> > measure?...or are there multiple places where voltage
> > should be measured?...and how is that
> > accomplished?...with a rotary switch?
>
> > Similarly=2C I've planned to place my ammeter in series
> > on the output side of the alternator...will that
> > do?...or again=2C are there multiple places where
> > amperage should be measured?...and if so=2C where?...and
> > how is that generally accomplished?...with a rotary
> > switch?
>
> > (I have the EXP 2 Bus by Control Vision along w/ their
> > indicator module=3B however=2C the word I'm getting from
> > others is that the warning lights on the module are not
> > to be trusted=2C and that led to my purchasing a
> > delightful little pair of Mitchell instruments.)
>
> In certified planes the amps are sometimes measured out of
> the alternator regulator (plus scale only) or in/out of
> the battery (plus and minus scale)
>
> The latter is more useful but often is not the case
>
> Voltmeters are damped so they don't move violently.
> Ammeters aren't (mine anyway - analogue not digital) and
> can change rapidly. Tha is why i knew that all four Ducati
> replacments I tried after my first one died at 175 hours
> were not working the way I would want - a 5 cycle per sec
> oscillation between 2 and 10 amps - which would have also
> been the volts oscillating between probabaly 13.5 and 15
> volts.
>
> With only a voltmeter I would have been unaware of this
> (maybe that would have been better).
>
> I found the Schicke recifier/regulator and it has been
> perfectly normal ever since with no oscillations.
>
> And that word "oscillations" is a hint why you should NOT
> put an ammeter in the line between the stator and the RR.
> The stator produces AC voltage and therefore current so
> the ammeter would read zero unless you had an AC ammeter !
> I measured up to 30 v AC coming out of the stator at full
> welly.
>
> This all means that I would always have an ammeter AND a
> voltmeter. On=3By with both can you be sure of what is
> happening. The voltmeter can be digital=2C but an analogue
> ammeter is the best way.
>
>
> In terms of this resistor=2C you can either put the whole
> current through an ammeter (made to suit) in which case
> the current is measured across a small value resistor
> inside=3B or the small resistor (known as a "shunt") can be
> fixed in the cable and the ammeter measures across it.
> This "shunt" way avoids long runs of cable into the panel
> taking the whole current (with Rotax is it not much - max
> 19 A)
>
> HIR (Hope I'm Right !)
>
> Richard Holder
> G-OWWW
>
===========
===========
===========
===========
>
>
>
|