Battery Replacement and Cold Cranking Amps

There was a recent article in Aviation Consumer about the
differences between batteries.

Yes, I read the article, but I was a bit confused about which batteries
were "equivalent" to mine and could be used in my aircraft. Another
responder in this thread answered that question.

I hope that you are preheating the engine
before starting in the cold and if you have Tanis heaters, you can add a
battery heater which will help a lot.

I was preheating with forced hot air from an external heater. Last
Friday, I added a Tanis heater. Does one "add a battery heater" by
getting it from Tanis and having an A&P install it?


Mike
MU-2


"O. Sami Saydjari" wrote in message
...

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)

Great. I am certain that this level of capacity testing was not done. I
will have it done soon and let you know. Thanks.

-sami

MikeM wrote:

"Testing" the battery means making sure it is fully charged, then
discharging it using a known load current, timing how long it takes
the voltage to reach 11.5V, and then computing the capacity by
multiplying the time to reach 11.5V by the load current.

According to Gill & the FAA, your battery should be up to delivering
a load current representing all the stuff it takes to get safely on the
ground for 30 min: this should include engine instruments, fuel gauges,
electric gyros, radios, transponder and some lighting.

A guess for the essential electrical load on your aircraft would
be about 25A. To test the battery, connect a 12V/25A=0.48 Ohm,
12V*25A=300W resistor to the battery, and time how long it takes
the battery to reach 11.5V. If your battery wont hold up this
load for 30 min, then it should be replaced...

Cranking is a separate test. An automotive service-station type of
carbon-pile battery tester can be used to put a load of ~225A on
the battery for 3 or so minutes. If the battery peters out short of
3 min, then replace it.

MikeM

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)

Sami,
One battery heater supplier is:
http://www.reiffpreheat.com/Battery%20Heater.htm
Michelle

O. Sami Saydjari wrote:

Wow...thanks.

Michelle P wrote:

Sami,
You can install a Concorde www.concordebattery.com CB-25, CB-25XC,
RG-25 or RG-25XC.


Gee, I wish my A&P knew this. Growl.

1) Four attempted starts depends on how long you were trying. Most
starters have a 30 second continuous limit.
using that that is 2 full minutes of cranking. That would just about
be the limit for battery capacity.


I see. OK. So, it sounds like 4 tries is about all I can expect, no
matter what battery I get?! Guess I need to get better at this
starting thing!

2) Has your aircraft had the original battery cable (Aluminum in most
models) with the Bogert Copper Cable kit? This improves starting
speed and longevity.


The new cable kit has been installed.

3) Find a more open minded A&P Concorde recently modified the battery
cases so they will fit in the Piper Battery Box.


Good to know. Thanks.

4) Place your battery on a Charger for an hour a day. Low current. A
standard appliance timer works fine.


This may be a bit awkward. My aircarft is in a communal hanger (hmmm,
sounds communist) and they need to move it around from time to time to
get to other aircraft.

5) Use a battery heater.


Hmmm...I had not heard of those. Have you or anyone else on the
newsgroup had good experience with those? I wonder if I can somehow
link it to my (newly installed....just last week) Tanis heater?


Michelle (A&P)







--

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

wrote:
The most critical (and perhaps
counter-intuitive) thing to remember is that the mixture needs to be in full
LEAN (i.e. cutoff) position while cranking. You need to keep your right
hand on the mixture while you turn the key with your left hand so that you
can quickly move the mixture to full rich as soon as the engine begins to
fire.


Over the years, a lot of people have recommended this procedure (mostly
CFIs), but no one has explained to my satisfaction WHY this would work.
Why are you leaning the mixture at exactly the time an extra-rich
mixture is needed? After all, that is why we prime and crank with the
throttle mostly closed. I have come to believe it is one of those old
wives tails that CFIs propagate to make it appear to students that they
are "fixing" a bad start.

Since I have been working on my instrument rating through the fall and
winter, I have been doing a lot more cold weather (well, California
cold) starts than I have in past years. My starts improved immensely after
I started doing one thing: after priming about 150% of my usual
warm-weather cold-start procedure, WAIT for 30-60 sec. before cranking.
This gives the primer fuel time to evaporate in the cylinders and form a
combustible mixture. Works every time, with no pumping of the mixture
control.


Ross Oliver

"O. Sami Saydjari" wrote in message
...

Does one "add a battery heater" by
getting it from Tanis and having an A&P install it?


Of course everybody needs to get paid.for your battery to be warm. It
shouldn't be too difficult though.

http://www.tanair.com/accessories.html#BATTERYHEATERS

Mike
MU-2

Ross Oliver wrote:
wrote:

The most critical (and perhaps
counter-intuitive) thing to remember is that the mixture needs to be in full
LEAN (i.e. cutoff) position while cranking. You need to keep your right
hand on the mixture while you turn the key with your left hand so that you
can quickly move the mixture to full rich as soon as the engine begins to
fire.



Over the years, a lot of people have recommended this procedure (mostly
CFIs), but no one has explained to my satisfaction WHY this would work.
Why are you leaning the mixture at exactly the time an extra-rich
mixture is needed? After all, that is why we prime and crank with the
throttle mostly closed. I have come to believe it is one of those old
wives tails that CFIs propagate to make it appear to students that they
are "fixing" a bad start.


Well, (1) it's what my POH says to do, and (2) it seems to work.

Remove SHIRT to reply directly.

Dave

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

(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

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

On 27-Jan-2004, "O. Sami Saydjari" wrote:

But when you say it "ran out of juice after 4 attempted starts" I am
wondering (a) what you mean
by no juice,

I mean that the battery would no longer turn the engine over. The
instruments were still powered.

and (b) what constitutes an "attempt."

An attempt was about 30 seconds of turning the engine over in attempt to
get it to start.

Well, from what you say your (cold) battery is able to crank the engine for
a total of about 2 minutes before it gets run down. That doesn't sound too
bad to me. You should note, however, that cranking non-stop for 30 seconds
is way too long. You are probably over-heating your starter. Anyway, the
real problem isn't your battery but that your (preheated) engine failed to
start. Properly preheated, it SHOULD start with no difficulty. I would
strongly suspect the impulse gear in the left mag. Or you may be flooding
the engine because of improper start technique (a preheated engine needs
only a little bit of priming) or because of a mechanical problem with the
fuel injection system. After cranking unsuccessfully for a bit, try the
"flooded engine" start technique. (Electric fuel pump OFF, Throttle FULL
OPEN, mixture to IDLE CUT-OFF.)



If you mean that the battery is discharged to a point where the prop
will no longer turn with
the starter, that could mean a lot of things, including a defective
starter.


Hmmm, how does one determine if the starter is the problem?

That doesn't sound like your problem, but a starter would be suspect if it
failed to vigorously crank the engine with a freshly charged battery. Of
course, that problem could be caused by other problems such as loose
electrical connections or corroded battery terminals.


-Elliott Drucker