The alternator checked out OK. The last flight I flew I left both the
fuel pumps on
the whole flight. Usually, I only use both when on take off and landing.
Maybe the
current draw was too much for the 40 amp alternator. The guy at the
alternator shop
said that at and above 2/3 the rated current, the voltage starts
to drop off. Hmm. I have two of the fuel pumps that Tracy sells, I
don't know what the current draw on them is, a dynon D10- 1 amp
aproximately, Xcom radio- . 5 amp, Terra transponder- .75 amps, EC2
and EM2- ? amps, 4 LS1 coils- ? amps and two 18 AH saturated mat
batteries.
Maybe time to do a current check on the batteries and trade one
out for a new one. I have a new one, the old ones are coming up to
two years old. I have them on a float charger anytime I'm not
running the engine. Any thoughts?
Brian Trubee
You need an ammeter.
Paul Lamar
Brian,
In my opnion you do not need a ammeter as only more
weight! The voltmeter will tell you what state your battery is, you
do not really need to know what the alternator is putting out. If
the voltage is going down and the alt is OK then you alt is not up
to the job! as dale? said put a clamp-on the alternator output and turn
EVERYTHING on and watch the voltmeter and if the draw is more than say
30 amps get a bigger alternator or ditch some of the load.
John Burey
.
Get realistic John. The weight is ounces. You cannot have too much
information. An ammeter gives an instant early warning of what can happen.
If suddenly the ammeter shows a discharge the EFI and electronic ignition
engine is
going to stop sooner or later. You can then turn off non essential
electric devices
to give you more time to land. You will instantly know if you have solved
the
problem. You can't just pull over to the side of road and stop.
Paul Lamar
I generally don't like to wire an amp meter in the instrument panel
as it would require either a 8 or 6 AWG gauge wire for a maximum
curare of 40a or 50a, respectively .
A good alternative is to wire in a low voltage warning light in addition
to the
voltage meter.
Joel
Another alternative is have a red warning light come on when there
is discharge condition.
Paul Lamar
Use an induction coil ammeter with the coil around the main battery wire.
Simple, just needs to be calibrated.
Kevin Alderman
Paul is correct with the idiot light. Use a LED red. Takes up almost no
space
in the panel and is highly visible when there is a problem. Check the
voltage
the LED is designed for and install a dropping resistor in series if
required.
A lower resistance will let it be brighter. Small wire from alternator
light
terminal to the LED, which saves weight.
Note my previous post with Bosch fuel pump amps. Could be between 5A and
15.5A. If yours are in the 15A range times two is 30 plus the panel and
don't
forget lights. You could be at the 40A output. You need to try a clamp-on
amp
meter for test to verify. Even if you measure the pump amps times 2.
Dale Davies
WTF if weight is an issue empty the change in ya wallet, take a pee
before flying, Do your checks, look at your gauges, then fly. you
know better mate, c'mon. Knowledge is power.
Graeme Riley
Let me join in here. Our club planes have had a couple of instances where
the alternator gave up the ghost, and the ammeter indicated a discharge,
but
the pilot and instructor pilot did not notice the little needle moving the
wrong way with no other indication -- until the radio's started to drop
out.
On the other hand, I have a 'low voltage' light (big flashing yellow) that
comes on if the voltage on the bus drops below 13.5 volts, so if the
alternator drops out, I get an 'immediate' and hard to ignore indication to
start checking things. Has happened once, and was able to return to hanger
to check out the failed alternator.
I like the light to get your attention -- if installing an ammeter, still
have the light, because most ammeters are small and inconspicuous and easy
to miss on a scan.
Bill Schertz
KIS Cruiser #4045
N343BS
Phase one testing Completed
I am about to start the wiring harness of my Wheeler- and I plan to include
more instrumentation than my certified plane had. But selectively more. I
took apart the Viking partly to re-use some of the parts, avionics, etc.
part to see exactly what I had paid those IAs to do over the years that I
legally couldn't do. I was surprised at what I found- wires that had
insulation missing due to cracking off and age, cables that were over half
worn, pulley wheels that the bushings had fallen completely out of, and the
list goes on. I all but gave away my Continental IO 520 because I couldn't
economically overhaul it because of 2 ADs, but I could repair it and fly it
after removing a tablespoon of metal from the oil. No thanks.
After owning the Viking for almost 3 years and 250 hours of flying, the
inadequacy of the electrical system and the engine monitoring system were
the 2 biggest headaches for me. With that knowledge, my Wheeler will be
constructed to include some of the certified requirements, and some that
are OK in experimental but not OK in Certified.
I have mechanical oil pressure, oil temp and water temp gauges. I will also
have an electronic data logging system that I can review on the ground. The
data logging system will record engine parameters, as well as G loads,
acceleration, atmospheric pressures, temps, etc. That part is easy. Part of
this system will be an LED like my truck has- it says CHECK GAUGES. simple.
If something is outside of the limits, I get a light and it tells me to
look at the panel. I much prefer this to the alternative of suddenly seeing
steam and then all of the coolant is gone, or my alternator quit an hour
ago and now my engine dies from no spark or electronic ignition. Normally,
alternator failure wont kill the engine, but add a dead battery and it will
in our case. So, knowing that the alternator just went on vacation is a
flight safety issue. Likewise, overheating or oil pressure loss is a show
stopper, and I want to know this ASAP as well.
A warning light that tells us that something bad has happened or is about
to happen is good insurance. A distraction, maybe. But so is losing an
engine on final because of a dead battery, or during climbout due to
overheating.
My opinion on the battery issue is this- if your engine is totally
electronic or electric(i.e. no mechanical ignition system) then I would
install a battery that will last for a few hours if the alternator goes
dead. My choice is the AGM Optima batteries that are sold at auto parts
stores- plenty of CCA, good reserve time, and weight of 34 lbs. Non
spillable, and will still make power with a hole in it. For $189.00, again,
cheap insurance.
Kevin Alderman
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