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
Paul,
I was really only joking about the weight, but, in my
opinion the best meter is a volt meter because it will always tell you
the state of your battery/s, and to fit a ammeter especially in Brians
case its a Velocity? if so you will need long leads for a shunt type or
you will have a large voltage drop unless you have heavy ammeter leads
all the way to the panel. I have found in the field that if the operator
understands how to read a voltmeter it is the best instrument, of course
you can have the best of both worlds by having both, but ammeter will
never tell you if battery is flat or getting low! As in Brians case the
voltmeter will tell you if say your ignition is about to die, or your
pumps are about to slow down and not supply the fuel pressure. Depends
where one fits the ammeter what it tells you, on the alternator lead and
it will tell you how much the alt is charging, fit it between battery
and load and you know if you have a plus or minus into your battery, but
you do not know if your load is the max that the alt can cope with. I
think that is why most manufactures fit a voltmeter these days!;-)
John Burey.
You are talking about the old fashion ammeters. The shunt can be placed anywhere and
long small low current wires used to send the info to the remote digital display.
Read these pdf.
Paul Lamar
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