Today's Message Index:
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1. 07:50 AM - Re:Adding an electrical system (Speedy11@aol.com)
2. 08:12 AM - Re: Re:Adding an electrical system (Robert L. Nuckolls, III)
3. 08:56 AM - Re: Low Voltage Disconnect needed (rparigor@suffolk.lib.ny.us)
4. 11:38 PM - OT: analog VOM worth battery cost. (rayj)
Message 1
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| Subject: | Re:Adding an electrical system |
Bob,
Your points are all well taken.
But, the customer wants a complete electrical system installed including
some type of charging system. I suggested to him that the demand on the
battery will be nominal for the short 1 hours flights he plans in the
airplane. There will be no long distance flights. I suggested a battery only
electrical system and charging the battery between flights. But, he insists on
a system with charging capability. So, the only option is to install an
external wind generator for recharging.
Do I need a voltage regulator for this setup?
As mentioned, the airplane will be flown only occasionally and only
locally. It will be in a flying museum in Chile. We will install a charging
point for the battery so it can be maintained to full charge between flights.
I am considering the RG-35 battery only because it was used in a previous
337-approved PT-22 installation so reapproval will be much easier by using
the same battery.
>From my experience, a single PC-680 battery will just barely turn over my
IO-390. I have two in the plane and have to connect both to get good
rotation of the engine.
The PT-22 has a radial (not sure yet which one) and I'm not sure that the
PC-680 will have enough juice to spin it well.
Since we are installing a starter on the engine, we can afford some weight
in the aft fuselage (behind seat) for the battery weight.
I'm planning to use #2 wire from the battery forward.
The power demands from the Becker radio and transponder are minimal. Your
numbers are for the VHF radio.
Standby" reception mode 70 mA
Reception mode 500 mA
Transmission mode 2.5 A
The transponder requires only
Standby - 0.3A
Transmit - 1.1A
So, the inflight demand on the battery will be zero when the wind generator
is producing 5A.
I agree that the RG-35AXC is a monster. It is very heavy which translates
into extra weight for the stronger battery mount required. What do you
think of using an Aerovoltz lithium battery? It has about 550CCA and shelf
life is excellent (10% loss over one year). Otherwise, I will lean toward
the PC-680 - or maybe a pair of them.
The main concern overall for this installation is that the cranking power
must be sufficient to start the engine. All other demands on the system
are achievable.
More thoughts?
Stan Sutterfield
In a message dated 8/23/2012 3:01:37 A.M. Eastern Daylight Time,
aeroelectric-list@matronics.com writes:
I am adding an electrical system to a PT-22 per a
customer's request. It will consist of an
overhauled Eclipse Y-150 starter, a RG battery,
starter switch and contactor, a switched bus to
power a Becker radio and transponder, a wind
driven generator, and associated wiring.
Does anyone have experience with adding electrical to a PT-22?
Any gotchas?
I can't find any generator or alternator that is
approved for the PT engine, that's the reason for
the wind generator. It will only produce about 5
amps, so it will barely power the transponder and
slowly recharge the battery and allow occasional radio transmission.
Since I'm doing a form 337 for the change, I
should be able to use any battery. So, we're
considering a PC-680 or a lithium ion battery
such as the Aerovoltz. Otherwise, we'll us a RG-35AXC.
What are your design goals for the installation and
how do you envision it will be used operationally?
Will this airplane be used for cross-country flight?
Is it parked in a location serviced by AC mains power?
Keep in mind that cranking an engine from the
typical battery takes only 5% or so of that
battery's capacity. Transponders take typically
2 amps to operate when generating lots of replies.
If I recall correctly, the Becker was designed
for battery only ops in gliders. It's power
demans are:
Standby" reception mode =A3 70 mA
Reception mode =A3 500 mA
Transmission mode =A3 2.5 A
Energy demands for this instance are trivial.
Further, it has a low voltage warning built
in set to trigger at 10.5 volts.
http://tinyurl.com/9upvqxg
An RG-35 is a beast of a battery . . . 30+
pounds as I recall. B&C did some cranking tests
on the SMALLER cousin to the PC-680 and found
that it would do a 10-blade crank of a high
compression engine (aerobatic aircraft), 5
times in a row (with about a minute cool down
between events). The PC-680 should do better
yet.
How about NO generator, a PC-680 as the only
battery and a Battery Minder plugged in while
the airplane is parked? Li-FePOH batteries
are low risk because you're not going to charge
it at a high rate while airborne . . . and it
can be recharged at a benign rate while hangared.
But take care also that you do not heavily discharge
it between flights as they're more sensitive to
deep cycle damage than their SVLA cousins.
Bob . . .
Message 2
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| Subject: | Re:Adding an electrical system |
>
>More thoughts?
Sounds like you have a plan. 5A applied to
an RG35 probably doesn't represent much of
an OV risk. But it would be easy to add
crowbar protection right on the b-lead
breaker.
Bob . . .
Message 3
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| Subject: | Re: Low Voltage Disconnect needed |
Hi Bob
Thx. for the info.
Ron P.
> Here's both all solid state and a relay version
> of what I think you asked for. I'd go with the
> MosFet version. FETs are quite rugged these days.
>
> http://tinyurl.com/9lc72qs
Message 4
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| Subject: | OT: analog VOM worth battery cost. |
Greetings,
I have a Triplet 630-NA VOM. I'm wondering if it is a good enough
quality VOM to justify putting $15 worth of batteries into.
Opinions please.
do not archive
--
Raymond Julian
Kettle River, MN.
"And you know that I could have me a million more friends,
and all I'd have to lose is my point of view." - John Prine
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