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.
Hi Brian,
What is the total draw of all you instruments, lights, the fuel pump, etc.
You may be close to the max output of the alternator and if that is the case
it will not last. Charge the batteries and if you need to, borrow a multi
meter with a clamp-on current pickup. You will then be able to measure the
current the alternator IS putting out and the electrical draw with everything
required turned on. If a diode pooped the bed, the output will be 2/3 normal
and the alternator will get hotter than normal.
I would be inclined to use a Delco 60A alternator. They are bulkier and
heavier, BUT they are dead simple to repair once you find a place to sell the
individual parts. Also they use machine screws and nuts to attach all the
components. A lot of the others require soldering to rebuild and that is a
major pain in the sit down. There was millions built so cores and parts are
readily available at recyclers. To me the benefits outweigh the disadvantages.
But before getting all excited and pulling the alternator off, do the checks
and find out exactly what the problem is.
Dale Davies
What about using LiFePo batteries as they keep well when not using
the plane and are much lighter? There is approx 3,2 V to a cell so
any size could be constructed in by 4 cells times X depending on your
Ah needs.
The size I am using for an E-bike have a little less than 1Ah/ cell .
My Bike runs on 48V and 15 Ah, weight 7,5 kgs has 16 cells.
The guy that builds them will do so to your specs and is one of the
few Chinese companies that actually understands the word Service
...http://www.pingbattery.com
They normaly do 24 V and uppwards but their main market is E-bikes and scooters
However I am ignorant how well that will work with standard car
alternators./ Robert
--
Robert Lindwall
Call me a chicken, but I wouldn't put a LiPo battery into an airplane I'll be riding
in until they don't appear to be a fire hazard.
If this sounds alarmist, I was just reading how Cessna had spent a huge pile of money
in designing and qualifying a LiPo battery system in one of their Citation Jets..
Just as they were releasing the associated airplane, they had a fire in the battery
system - while the airplane was at a trade show. In response, Cessna issued an AD to
replace the LiPo batteries in all of the airplanes they had just shipped.
There probably is a way to make these things work, but I don't see them as a good
risk yet. Focus on other methods of weight reduction - including that of the flight crew!
Matt-
--
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