I'm nearing the finish of my phase 1 testing, and am now looking for replacement
batteries. right now, I am using two of these:
http://www.power-sonic.com/images/powersonic/sla_batteries/ps_psg_series/12volt/PS-12180_11_Feb_21.pdf
.
They are on separate contact-ors, so I can use either or both when flying. I use both
when starting. They are two years old, and today when I went flying I noticed that
the voltage was getting down to 11.6 volts. after landing, the voltage was up around
12.3 volts. Usually I show around 13~13.6 volts when running. I always use a float
charger specifically designed for these batteries when the plane is put away. Usually
the float charger shows a slow charge, but when I cam back from flying today the
charger was showing a fast charge, meaning that the batteries were discharged a fair
amount. Any comments on the suitability of these batteries and suggestions on how to
test them out for holding a charge or otherwise determining
their suitability or not for my plane. I have a 40 amp Nippondenso alternator, and
run an Xcom radio, a terra transponder, Dynon D10, Tracys EM2 and EC2, and one fuel
pump(at a time unless landing or taking off) that draws around 4 and no more than 6
amps.
Thanks,
Brian Trubee
The 11.6 V is normal for sealed lead acid battery when not charging.
Other people are using the same type successfully.
They need to be charged from time to time when sitting around.
My guess is every 2 weeks.
Paul Lamar
I'm pretty sure that this is a charging issue that just cropped up on this last
flight- I usually run in the upper 13s voltwise but noticed the low voltage while out
flying yesterday. My float charger will automatically go to float charge unless the
batteries are discharged when I put the charger on when I put the plane away. I will
then turn on the master to see if the charger goes to fast charge, which it will do
if there is a drain on the battery. So, what I deduce is that the charging system has
been working up until the last flight. It should be easy to troubleshoot the problem.
I'll post what I find after I find it.
Any comments on the suitability of the Powersonic PS 12180 NB batteries? I use two
of them, they are 18 AH, so I suppose with the relatively small load I use in flight,
I should have a fair amount of reserve if the alternator quits.
Brian
The battery voltage when charging should be 13.5 to 14.8. Do you have an ammeter in
the circuit.
Paul Lamar
No ammeter.
Brian Trubee
Hi Paul,
Re charging voltage into a 12 volt lead acid
battery, most car regulators charge at between 13.8 hot weather and 14.4
cold weather, the regulators are temperature compensated, I have found
that if they are charging at less than 13.8 v (at least in Australia),
the batteries will not fully charge, and conversely if charged at over
14.4 v they will boil the guts out of the battery! Of course our
temperature range is not as extreme as you have in the States;-) .
Brian, if your voltage is getting that low when the engine is running at
a moderate speed, your alternator is at fault, probably a diode bank has
gone to diode heaven!! If the alternator is rated at 40 amps it should
be able to charge enough to keep the voltage above 13 volts at a current
draw of 40 amps, it sounds like you have nowhere near that load. If your
batteries will start the engine they are good enough, just need the
alternator to keep them charged, sounds like your float charger is
keeping them charged then when you fly they are going flat!! When flying
you should have a minimum of 14 volts by the time you have warmed up the
engine and taxied to takeoff you should have 14 volts.
John Burey.
-- I think you guys are right. Every flight before this last one had my system
voltage in the upper 13s, except for this last flight. I keep the batteries on a
float charger that is designed for these batteries just to keep them topped up. On
the flight on friday, I noticed my voltage drop and will now take the alternator and
bench test it at NAPA. It's a Nippondenso 40 amp alternator with an internal
regulator. I have a blast tube to blow air over it, but that might not be effective
due to air flow characteristics. (Sometimes the air does not flow the way you think
it should. I have a NACA duct on top of the cowl that goes to a 3/4 inch dia scat
tube that blows air (theorectly) over the alternator) The tube is directed at the
back of the alternator where the regulator is located. The air flow might not be
sufficient to cool the regulator. In any case, my suspicions are that the
alternato/regulator is bad.
I'll know tomorrow.
Brian Trubee
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