Battery Replacement and Cold Cranking Amps

Thanks for the informed input. The resistance across the contacts
would get larger as the solenoid ages, and there are a lot of old
solenoids out there. We had a starter solenoid weld itself closed and
burn out the starter. New starter $1200, new solenoid $28. They're
worth replacing.
Two other items that can cause hard starting in the cold: (1)The
impulse couplings on the mags can get sludged up somewhat, and when
cold they won't give the sharp snap needed to make a spark. (2)If the
engine isn't preheated and the weather is cold enough, the first
combustion cycles will create enough water vapour in the cylinders to
frost the sparkplug electrodes and short them. My old A-65 is famous
for this. You get a very brief run and then it dies, and no amount of
fooling with it will make it go.

Dan

Michelle P wrote in message k.net...
Dan,
No voltage across the contact is unrealistic. O.5 volt is considered to
be the acceptable limit.
If you replace the master and starter solenoids. Have your A&P install
diodes reverse to the flow across the contractor terminals. The will
prevent the contact from arcing when they disengage. It is the contact
arcing that increases the resistance and causes the voltage drop. 0.5
volts across the contacts is 0.0013 ohms.
Michelle

Dan Thomas wrote:

Often overlooked are the master and starter solenoids. These things
get burned contacts and they begin to present a resistance that shows
up as reluctant cranking. A voltmeter placed across the solenoids' big
terminals should show 13 volts when the system is off, and NO voltage
when it's on (or cranking). Any voltage while the solenoid is closed
indicates resistance across the contacts. Even a small amount of
resistance at high current flows will cause significant voltage drop
(E=I*R; A .02 ohm resistance at 200 amps gives a 4-volt drop). Check
the cable connections the same way. Check both the master and starter
solenoids with the engine cranking.
An ohmmeter isn't really good enough to detect bad solenoid
contacts. The resistances are small, and increase with heat caused by
electical flow. An ohmmeter won't detect the heated resistance.


Dan



--

Michelle P ATP-ASEL, CP-AMEL, and AMT-A&P

"Elisabeth" a Maule M-7-235B (no two are alike)

Volunteer Pilot, Angel Flight Mid-Atlantic

Volunteer Builder, Habitat for Humanity

(Dan Thomas) writes:

Often overlooked are the master and starter solenoids. These things
get burned contacts and they begin to present a resistance that shows
up as reluctant cranking. A voltmeter placed across the solenoids' big
terminals should show 13 volts when the system is off, and NO voltage
when it's on (or cranking).

Actually, get the meter probes on the WIRES, as the path
look like this:


wire-lug-nut-bolt-solenoid-bolt-nut-lug-wire

By measuring from the wire to the wire, you confirm that the lug's
well-connected to the wire, the nut is cleanly contacting the lug,
etc....

You likely want an analog meter (remember those) as it will be hard to
read bouncing digits on a DVM.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Here is an update on the battery saga. I had a different A&P do a
capacity test. He advised me that my battery fell below some reaonsable
threshold voltage within seconds. Time for a new battery. Arg, I am so
frustrated with the other A&P for not taking the time to do a real test.

Oh, and the previous A&P advised me that I had a Gill G25 battery. So,
I ordered a Concorde RG 25XC to get the added cranking power. Well,
unfortunately, it turns out I have a Gill G35, so they ordered the wrong
battery and it would cause a 2-3 day delay in the replacement to order
the RG-35AXC. So, now I am going with a new Gill 35.

-Sami
N2057M Piper Turno Arrow III

O. Sami Saydjari wrote:
I have a Gill G25 battery in my Piper Arrow III (PA28R-201T). I
recently had a situation where I ran out of juice after 4 attempted
starts. While I am sure that I can improve my starting technique (I am
a newbie for this particular plane), I would like to have a bit more
power in my battery, especially in very cold conditions such as we have
up here in central Wisconsin.

An A&P told me recently that I am "stuck" with my G25 battery. He said
that he tested it and that it was "fine."

Based on a recent article in "Aviation Consumer", I learned that the G25
has only about 225 cold cranking amps. I noted that the G35S has 250
cold cranking amps.

(1) Is it true that I am stuck with a G25 battery and that NO OTHER
battery in the world can go in my plane? I find that a little hard to
believe.

(2) If there are other possibilities, can someone recommend one that has
better cold cranking amps that the G25?

Thanks in advance.

-Sami (N2057M, Piper Turbo Arrow III owner)

"O. Sami Saydjari" wrote in
:

Oh, and the previous A&P advised me that I had a Gill G25 battery.
So, I ordered a Concorde RG 25XC to get the added cranking power.
Well, unfortunately, it turns out I have a Gill G35, so they ordered
the wrong battery and it would cause a 2-3 day delay in the
replacement to order the RG-35AXC. So, now I am going with a new Gill
35.

A lot of smaller A&P's don't actually have a load tester (or much of
anything else in the way of test equipment). Unfortunate, but that's
the way it is.

FWIW, one turbo-Arrow III owner to another, I really like the RG-35
series, but haven't had very good luck with them in my Arrow (in spite
of carefully checking voltages, copper cables, etc.). Other folks have
results that tends to follow one of two patterns. Either, like me, the
Concorde RG batteries are really good for only a few months and limp
along for another six or so; or they seem to work great for years and
years. [And I have seen what seems to be a breakdown between the two
results along the lines of the type of plane.... but don't know why.]

The wet cell type (like the G35 you are getting) seem to work better for
me. OTOH, I keep trying -- I now have a new RG-35AXC in there, and it
DOES seem to be lasting longer than the RG-35 or RG-35AX did (which
wasn't all that long).

I know you haven't had the Arrow long. It's a great plane and I think
you will enjoy it a lot. But you might want to start getting to know
more about the hardware. The logbooks can make some very interesting
reading (especially between the lines) and will tell you things like
what kind of battery you have, and when your vacuum pump was last
replaced, or the last time your AI was overhauled. Fun *and* useful
reading for a cold winter evening.

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------