n234nw
Posts: 67
Joined: Tue Jul 05, 2005 5:06 am

Tell Me About Aircraft Batteries..

Sun Nov 12, 2006 2:04 pm

I know that aircraft have batteries, but I have not been able to find much information on them. A photo search turned up nothing. I even checked my DC-10 operating manual. I understand they are used for powering up the APU, emergency systems, etc.

What do aircraft batteries look like?
Where are they located?
What are type are they? (I'm guessing sealed lead-acid?)
 
futurecaptain
Posts: 1918
Joined: Sat Sep 09, 2006 1:54 am

RE: Tell Me About Aircraft Batteries..

Sun Nov 12, 2006 2:21 pm

Well, for the planes I'm most familiar with, small cessnas....

Quoting N234NW (Thread starter):
What do aircraft batteries look like?

Kinda like your car battery. A box with positive and negative terminals with some wires hooked up to each end. 24 volts.

Quoting N234NW (Thread starter):
Where are they located?

Just past the firewall on the right side.

Quoting N234NW (Thread starter):
What are type are they? (I'm guessing sealed lead-acid?)

And your guess would be right. Proven technology, safe, and reliable.....well, for the most part.

I'll let someone else tell you about the big jets.
AirSO. ASpaceO. ASOnline. ASO.com ASO. ASO. ASO. ASO. ASO.
 
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jetmech
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RE: Tell Me About Aircraft Batteries..

Sun Nov 12, 2006 2:46 pm

G'day N234NW  Smile ,

Check out this link if you wan to know some more about aircraft batteries;

http://www.saftbatteries.com/020-MS_Aviation/20-10-10_aircraft.asp

Saft is the company that makes the batteries I have seen on B747 / B767. I am not too sure who makes the batteries for Airbus.

Quoting N234NW (Thread starter):
What do aircraft batteries look like?

Play around with the link I have sent you. The batteries I have seen on Boeings and Airbus are usually large steel cubes with the rough dimensions of about 15" on each side. They contain dozens of smaller cells inside.

Quoting N234NW (Thread starter):
Where are they located?

I think there are about 3 or 4 separate aircraft batteries on Boeings / Airbus. The APU usually has it's own battery located near the tail section, with several other batteries providing emergency power. I have seen these batteries below the flight deck in Airbus and behind the cockpit in B747 classics.

Quoting N234NW (Thread starter):
What are type are they? (I'm guessing sealed lead-acid?)

I think these batteries I saw were NiCd and I hazard to guess that the newer ones are Li-ion  Confused .

Anyway, thats all I can tell you as my trade is mechanical, not avionics. The thing you have to be careful with on these particular batteries is that the terminals are located fairly close together on one of the sides.

An avionics person was once removing a battery and neglected to put a cover on the exposed terminals. Due to these batteries being very heavy, he had to bring it close to his body to lift. Unfortunately, he grounded the terminals together on his metallic belt buckle.

The result was much sparking and smoke as the terminals fused with his belt buckle. He was not harmed, but I presume he needed a new belt as well as a change of underwear, and he would never again neglect to cover the terminals with a safety blank  bigthumbsup  !
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
erj-145mech
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RE: Tell Me About Aircraft Batteries..

Sun Nov 12, 2006 8:56 pm

The battery in my plane, a Cessna O-2A is a lead acid wet type battery. It weighs 34 lbs, has an output of 24 volts, with an 11 amp/hour capacity. Originally it was a ni-cad from the factory, and is mounted in the baggage compartment.

The Embraer ERJ 135/145 series airplanes have two ni-cad batteries in the nose on the left side between the nose landing gear and the windshild.

The B-17G has three lead acid batteries mounted in the leading edges of the left and right wings, two on the right, one on the left. Each one weighs 89 lbs with 24 volts output.

The P-38L has one 24 volt lead acid battery in the left boom, aft of the radiators.

Every aircraft manufacturer has a different location and type for the aircraft/
 
777wt
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 12:58 am

Quoting Erj-145mech (Reply 3):
The Embraer ERJ 135/145 series airplanes have two ni-cad batteries in the nose on the left side between the nose landing gear and the windshild.

They are heavy! About 80 lbs per battery.
One is for the electrical system and the other is for the APU starting.

Once you turn both battery master buses on, you have about 3 mins to get the APU online or the batteries will drain to below 23 volts which an APU start cannot be done.

Also in the wintertime if the plane has been sitting overnite, sometimes the batteries don't have enough juice to get the APU started so a GPU would have to be used.

Whenever one of the ERJ-145 is found with a low voltage by the pilots, we have to replace both of them. They are secured on with an connector which has a knob to tighten it on. And ONLY copper safety wires must be used on the battery area.

One time I found steel safety wire there and the AMM states ONLY copper should be used...
 
2H4
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 1:06 am



The Mooney M-20R Ovation has two batteries, which is a wonderful feature when the pilot from the previous flight forgets to turn off the master.

I'm looking forward to reading interesting battery stories in this thread, involving acid leaks, thermal runaway, etc...  Wink



2H4


Intentionally Left Blank
 
corey07850
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 2:06 am

A couple people have said it, but I want to reiterate... they are heavy!!!
 
jetstar
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 2:43 am

The Lockheed JetStar has 2 ni-cad batteries and as delivered from the factory they were located in the baggage compartment, which was just opposite the entry door. There was a shelf above the battery compartment for the luggage. The batteries were located so far forward to offset the aft center of gravity because of the rear mounted engines.

Almost all JetStar operators opted to relocate the batteries during interior completion so they can enlarge the baggage compartment. On the 2 JetStar’s that I worked on, one had the batteries relocated to an empty space in the fuselage forward of the nose landing gear. The batteries were mounted one in front of the other and you had to reach in a tight area to reach the forward battery if you had to disconnect it. To remove them wasn’t that hard, just slide them out, but to install them you had to first get on you knees, brace your back on the nose landing gear and then lift the 60 pound battery first on to your lap and then lift it up about to your head and then slide it in. Because of this I ruptured myself and eventually had hernia surgery.

On the other JetStar I worked on the batteries were relocated to the inverter compartment, which was factory located under the floor in the entranceway to the cabin. 2 of the 3 inverters, both the main AC inverters were relocated to this same empty area in the nose leaving just the windshield inverter in its original location. Removal of the batteries for servicing was no problem, I made a lifting bar from a broom handle and 2 long bolts and was able to just lift the battery out very easily. Also in this configuration we had access to the batteries in flight. One time in flight the battery temperature sensor gauge kept jumping from normal to a hot battery warning setting off the master warning, so in flight I unscrewed the floor panel and after feeling the battery to determine that the battery was not overheating, I disconnected the sensor. The passengers never saw me do this because I had closed the cabin door.

Like all transport category aircraft, the JetStar had a single quick turn connector to disconnect both battery terminals on each battery.

Because the JetStar had electric starter motors, it was tough on the batteries and they required a lot more maintenance that larger aircraft with air start motors. The number one battery took more of a load than the number 2 battery during a battery start, so every 50 hours we would switch them around and every 100 hours we would remove them for servicing and deep cycling if needed, we had a spare set of batteries and then the serviced batteries would become the spare set.

The best battery installation was in the Gulfstream airplanes, they had the batteries located in the left fuselage under the engine. There was a panel that you opened and both batteries were right there at shoulder height. A lot of Gulfstream operators would often disconnect the batteries when leaving the airplane because there was a history of coming back to the airplane and finding the batteries dead because someone did not turn off the outside battery switch after raising the airstairs.

One of the of the weirdest battery configurations in an airplane that I worked was in a twin engine British airplane called a Beagle. This airplane had 2 batteries, the battery for the left engine was on the right side of the airplane and the battery for the right engine was on the left side. Also there was no way of connecting one battery to the other engine if one of the batteries was dead, so if the left battery was dead you could only start the right engine.

I do not know why this was designed it this way, maybe they thought you could take off on one engine and start the other in flight, just my thought.
 
474218
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 3:11 am

The L-1011 is equipped with a 26 volt, 22 cell, nickel-cadnium battery with a 53 amp-hour rating. The battery is located in the Mid Electrical Service Center (MESC), which is between the aft wall of the lower galley on the long body aircraft and the aft wall of the forward cargo compartment on the -500's and the wing front spar. It weights 115 pounds. At least one L-1011 operator (Gulf) had two batteries install at the factory. Like it was mention before these batteries do not look like automotive batteries, it is just a gray metal box.
 
Tristarsteve
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 3:50 am

Quoting 474218 (Reply 8):
At least one L-1011 operator (Gulf) had two batteries install at the factory.

The second battery on the GF Tristars was an spare. It was hooked up to the battery cooling system, but not connected electrically. We interchanged them once a week.
 
roseflyer
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 4:03 am

Quoting JetMech (Reply 2):
I think these batteries I saw were NiCd and I hazard to guess that the newer ones are Li-ion .

Yes the 787 will be switching to Li-ion batteries. The 787 has an electrical system far more powerful than any other airliner. There is also a big difference since the electrical generators will be used as starters for the engines. I'm not sure how the system is initiated with the APU turned off, but there is a test lab built at one of Boeing's contractors (Hamilton Sundstrand) that has the entire electrical system setup in a test lab called APSIF in which they are testing the integrated system prior to it ever being installed on the airplane. This is actually the first time that a single supplier has been responsible for the entire electrical system from source to load on a Boeing plane, so it is interesting how they are doing it and integrating the complex and very powerful system that can generate 1.5 MegaWatts of power.
If you have never designed an airplane part before, let the real designers do the work!
 
Tristarsteve
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 4:03 am

Strange thing about batteries on B737-3/4/500.
Some aircraft only have one battery.
Our -436 have 2 batteries. The second one is dedicated to APU start and is coupled up to the main battery when standby power is used.
We operate them on the same routes (non ETOPS) but on the two battery model both batteried must be serviceable for despatch, which always struck me as odd as half the fleet only has one battery.

Having said that, as long as the man that shuts the aircraft down at night turns off the batteries, they are always OK in the morning. If they are a bit flat, plugging in ground power will soon recharge them through the battery chargers.
On a B737 if they are really flat, plug in 28vDC and start the APU. Then remove the ground power. The batteries will charge at twice the rate.(worked on a B732, never had the need since)

On some aircraft, turning off the battery can be complicated. On the good old Tristar there are seven switches that must be off to ensure the battery is off.

APU master
Standby power
Emergency lights
2 x IRS (we only had two, with a third VG/DG.)
Radio master
and Battery.

There was an external APU control panel where you could exit the aircraft, close the doors electrically(essential on an L1011!) and then close down the APU and switch off the battery. But I never trusted it. I always exited the aircraft through the lower galley door after climbing down the lift shaft!

[Edited 2006-11-12 20:14:53]

[Edited 2006-11-12 20:20:20]
 
2H4
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 4:07 am




Quoting RoseFlyer (Reply 10):
very powerful system that can generate 1.5 MegaWatts of power.

Great scott! Before long, we'll be approaching 1.21 Jiggawatts....  Wink



2H4


Intentionally Left Blank
 
A10WARTHOG
Posts: 200
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 4:41 am

Quoting 777WT (Reply 4):
They are heavy! About 80 lbs per battery.
One is for the electrical system and the other is for the APU starting.

Either battery will power the plane if you have the ties set correctly

Quoting 777WT (Reply 4):
Once you turn both battery master buses on, you have about 3 mins to get the APU online or the batteries will drain to below 23 volts which an APU start cannot be done.

You know I have been told this, but personally have never had a problem. We tow aircraft to the hanger with batteries when a APU is inop it takes about 5 minutes and the volts never drop below 23.5. Maybe I have been lucky. We did have someone transfer hyd. using just the batteries. That drained them quickly.

Quoting 777WT (Reply 4):
One time I found steel safety wire there and the AMM states ONLY copper should be used...

My company our work card always any type of lockwire (copper, steel, brass). Personally I use copper, but I see alot of Brass.
 
Matt72033
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 8:29 am

Quoting JetMech (Reply 2):
I have seen these batteries below the flight deck in Airbus and behind the cockpit in B747 classics.

on the 400 its in the right hand crawlway in the lower 41
 
roseflyer
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 8:43 am

Quoting A10WARTHOG (Reply 13):
You know I have been told this, but personally have never had a problem. We tow aircraft to the hanger with batteries when a APU is inop it takes about 5 minutes and the volts never drop below 23.5. Maybe I have been lucky. We did have someone transfer hyd. using just the batteries. That drained them quickly.

Age of the batteries, temperature and other conditions have a big role in how long they will last. If you are dealing with a plane with batteries that are older on a cold winter day in ORD, you'd have a lot less battery life than you would on a new set in the summer in DFW.
If you have never designed an airplane part before, let the real designers do the work!
 
411A
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 10:24 am

>>There was an external APU control panel where you could exit the aircraft, close the doors electrically(essential on an L1011!) and then close down the APU and switch off the battery. But I never trusted it. I always exited the aircraft through the lower galley door after climbing down the lift shaft!<<

A typical case of not being trained properly, and NOT truly understanding the system installed by Lockheed.

RTFB, for best results.

Gee, what a surprise.
 
IFIXCF6
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 12:22 pm

DC10's have 2 battery "units" located in the Central Avionic Compartment (CAC). I call them units because they are wired in series, they are essentially "half batteries". 1 or the other gives you nothing, together they are the battery. This was typical of Douglas, and was used on most of their designs. BTW all NiCad.
Boeing likes to split the duties: a main ship (standby) battery, and an APU battery. Each 1 is a 28v battery, and each has certain buses to power. Again, NiCad.
Airbus...well the 310 has 3 batteries which appear to be 3 seperate units...end of my very limited AB experience!
L1011=I will kick the butt out of anyone asking me to install an L10 batt! (jk) It's 1 unit, very heavy, and awkward to get in place!
All NiCad's, and L1011's are physically larger.
They can be located anywhere.

Mike
 
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HAWK21M
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 5:00 pm

The B757 have Two Batteries.The Main in the MEC & the APU Battery in the Aft Compt E6.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tristarsteve
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 8:26 pm

Quoting 411A (Reply 16):
A typical case of not being trained properly, and NOT truly understanding the system installed by Lockheed

I knew how it worked, but when you are on a small charter airport miles from home and a spare battery would you trust it to turn off the battery for a nightstop, knowing you had 350 kids to pick up the next morning?

I think it was called Vittoria in Northern Spain. It was a very small airport for a L1011 and they only had a single airstart!

[Edited 2006-11-13 12:51:57]
 
avt007
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 10:24 pm

Better safe than sorry- I once had to jump start a 727 in the middle of the desert in Libya because the battery had died. The standard procedure was for the FE to disconnect it at night, but he forgot and the next day she was dead. A little ingenuity and a Twin Otter battery got them on their way.
 
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HAWK21M
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RE: Tell Me About Aircraft Batteries..

Mon Nov 13, 2006 10:57 pm

Quoting Avt007 (Reply 20):
I once had to jump start a 727 in the middle of

You referring to the APU right.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
avt007
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RE: Tell Me About Aircraft Batteries..

Wed Nov 15, 2006 10:26 am

Yes, I made a jumper cable basically that went from the Twotter battery (40AH) to the 727 battery connector (airframe side) . The FE started the APU, then all 3 engines, then turned off all the generators. I unhooked the battery, plugged in the ship battery, and away he went. IIRC, the Twotter battery was larger than the 727, since the PT-6 has an electric starter, but the 727 is only starting the APU.
 
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HAWK21M
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RE: Tell Me About Aircraft Batteries..

Wed Nov 15, 2006 3:35 pm

Quoting Avt007 (Reply 22):
I unhooked the battery, plugged in the ship battery, and away he went.

How long approx did it take.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
avt007
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RE: Tell Me About Aircraft Batteries..

Wed Nov 15, 2006 10:19 pm

Once the cable was made (adapted from a battery charger cable) it was pretty quick. But doing it on the ramp at 45 C made it seem longer! I was able to leave the Twotter battery on the ground, and the cable just reached up into the belly of the 727. About batteries, the Twotter uses a 40 amp hour main battery, ni-cad, made up of 20 individual cells. Each cell can be tested and replaced separately if need be. It also has an auxiliary battery of 7.2 amp hours for ignition on inflight restarts. Again 20 cells, and a real pain to keep in serviceable condition. Main made by SAFT.
 
411A
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RE: Tell Me About Aircraft Batteries..

Thu Nov 16, 2006 1:00 am

A thermal runaway condition in nickel-cadmium batteries was asked about by 2H4, so the following narative will provide same...

Scene, Libya, circa 1971.
Aircraft Fokker F.27 Mark 400.

This aircraft had two nickel-cadmium Batteries installed in the nose wheel well, and were not equipped with overheat sensors, as is required now.

At FL160, a very acrid electrical smell was noticed by both pilots, and a rapid descent and landing was made, to ascertain the problem.

Upon inspection, it was found that one battery had completly melted, and what was left in the associated battery box was nothing more that a mass of melted goo, which took nearly a whole day to clean up.

A new battery was sent out to concession 32, and installed the next day.

Three weeks later both F.27's owned by the company were equipped with battery overheat sensors, as the overheat incident happened to (oddly enough) the company Chief Pilot, and he absolutely was determined it would not happen again...ever.
 
474218
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RE: Tell Me About Aircraft Batteries..

Thu Nov 16, 2006 3:16 am

Quoting 411A (Reply 16):
I always exited the aircraft through the lower galley door after climbing down the lift shaft!<<

How did you get to the galley lift shaft, proper name rail? When the lifts are up it they are in the way. When the lifts are down the top of the lift would prevent you from reaching the galley. The proper way to egress through the galley is: Lower the lift, then hinged roof can be lifted and you can then lower yourself into the lift. Open the lift door and exit through the galley door. You can't climb down the "U" shaped rail tha contains the galley lift chain drive system.
 
SP90
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RE: Tell Me About Aircraft Batteries..

Thu Nov 16, 2006 4:28 am

This document from Boeing shows the 717 battery located below the flight deck.

http://www.boeing.com/commercial/airports/arff/arff717.pdf

Other Boeing planes.

http://www.boeing.com/commercial/airports/rescue_fire.htm

Any logical reason why Boeing decided to put the main battery on the flight deck under/behind the flight engineer console on the pre-400 models? I think where it is located on the 400 models (in the forward avionics bay) makes more sense.

[Edited 2006-11-15 20:44:55]
 
MD11Engineer
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RE: Tell Me About Aircraft Batteries..

Thu Nov 16, 2006 4:47 am

Quoting TristarSteve (Reply 11):
On a B737 if they are really flat, plug in 28vDC and start the APU. Then remove the ground power. The batteries will charge at twice the rate.(worked on a B732, never had the need since)

I've been working on B737s (all version from Jurrasic to NG) for the last ten years and have never encountered a 28V DC connector. The only external power connector is for 3 phase 115V AC.

Quoting 411A (Reply 25):
A thermal runaway condition in nickel-cadmium batteries was asked about by 2H4, so the following narative will provide same...

A thermal runaway is called like this because the pilot or engineer who discovers the condition better run away to get behind cover before the battery gives up it's ghost in a spectacular manner with all sorts of fireworks included.


Jan
Je Suis Charlie et je suis Ahmet aussi
 
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jetmech
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RE: Tell Me About Aircraft Batteries..

Thu Nov 16, 2006 12:24 pm

Quoting RoseFlyer (Reply 10):
There is also a big difference since the electrical generators will be used as starters for the engines. very powerful system that can generate 1.5 MegaWatts of power.

So Boeing are going with starter-generators in the 787. Isn't that already a common set-up with business jets?

Quoting Matt72033 (Reply 14):
on the 400 its in the right hand crawlway in the lower 41

That's where they are! All I could remember is seeing them on the flightdeck of the classics. The area forward of the crawlways always made for a warm and comfortable bed for a quick snooze  bigthumbsup !
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
411A
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RE: Tell Me About Aircraft Batteries..

Thu Nov 16, 2006 1:14 pm

You would never catch me climbing up/down the lift shafts, 474218, the quote was from the other guy.

I just use the APU panel on the fuselage underside, the way Lockheed intended.

Lockheed, a superior design!
A true gentlemens airplane.

Climbing up/down the lift shafts....phooey!
 
2H4
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RE: Tell Me About Aircraft Batteries..

Thu Nov 16, 2006 3:11 pm




Quoting 411A (Reply 25):
A thermal runaway condition in nickel-cadmium batteries was asked about by 2H4, so the following narative will provide same...

Thanks for the info, 411A.



2H4


Intentionally Left Blank
 
Tristarsteve
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RE: Tell Me About Aircraft Batteries..

Thu Nov 16, 2006 8:39 pm

Quoting MD11Engineer (Reply 28):
I've been working on B737s (all version from Jurrasic to NG) for the last ten years and have never encountered a 28V DC connector. The only external power connector is for 3 phase 115V AC.

Fitted to the GF B737-200, and on the BA B734. It is inside the fwd electronic bay on the floor beside the main battery. I have found it in the AMM 24-31-00 p7 Fig 4. but it does say ..if fitted..
It connects directly into the APU battery bus and then you can use the ground rig to start the APU.
I only remember using it once. On the B732 you had to have DC to start the APU., but on the B734 you could use ground AC, as the battery charger has an APU start mode.
 
474218
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RE: Tell Me About Aircraft Batteries..

Fri Nov 17, 2006 1:52 am

Quoting 411A (Reply 30):
You would never catch me climbing up/down the lift shafts, 474218, the quote was from the other guy.

Sorry, don't know what happened. I know you pilot types do your best to stay away from anything greasy.
 
Tristarsteve
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RE: Tell Me About Aircraft Batteries..

Fri Nov 17, 2006 2:25 am

Quoting 411A (Reply 30):
You would never catch me climbing up/down the lift shafts, 474218, the quote was from the other guy.

From the other guy, if you put the lifts down, there was a hatch in the roof to open, and a pull down step inside the lift cage. It was the emergency exit from the lower galley and the crew were meant to always have one lift down at all times. There was also a hatch abve the external galley door up into the cabin, but rarely used.
 
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HAWK21M
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RE: Tell Me About Aircraft Batteries..

Sun Nov 19, 2006 7:04 pm

Anyone experienced a Thermal runway snag on an Aircraft ever.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
DC8FriendShip
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RE: Tell Me About Aircraft Batteries..

Sun Nov 19, 2006 10:47 pm

The CRJ 200 and700/900 have two batteries located in the aft equipment bay. the 700/900's are aft of the door sitting pretty out in the open. the 200's more cramped but just forward of the door to the left. BTW i recommend muffs over earplugs if the APU is running.
Come fly the Friendly Skies of United
 
411A
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RE: Tell Me About Aircraft Batteries..

Mon Nov 20, 2006 7:55 am

Yes, see my previous post on the subject regarding thermal runaway in a Fokker F.27
 
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HAWK21M
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RE: Tell Me About Aircraft Batteries..

Mon Nov 20, 2006 11:04 pm

Quoting 411A (Reply 25):

Any corrosion detected over time.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
411A
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RE: Tell Me About Aircraft Batteries..

Tue Nov 21, 2006 1:14 am

No additional corrosion detected over time, as the battery box was replaced as soon as the overheat sensors were installed.

Thermal runaway...VERY nasty business.
 
A342
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RE: Tell Me About Aircraft Batteries..

Sat Sep 27, 2008 11:18 pm

Well, I have another question about aircraft batteries. Many types use Ni-Cd batteries, but these suffer from the well-known memory effect. How is this avoided on aircraft?
Exceptions confirm the rule.
 
T prop
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RE: Tell Me About Aircraft Batteries..

Sun Sep 28, 2008 12:53 am

DO228's had 2 NiCads up in the nose, 24v each. If I remember correctly they normally operated in parallel but on start they were connected in series and 48v was delivered to the electric starters. They needed to do this because the Garretts powering this airplane are single shaft engines and the starter has to rotate everything including the propeller.

Dash 8 normally has 2 NiCads up in the nose, one 40ah and one 15ah though a lot of operators switch the 15ah out to another 40ah. The Q400 has 3 NiCads in the nose 2 40ah and one 15ah. There is an STC for the earlier Dash 8's that does away with the NiCads and replaces them with sealed lead acid batteries. These are great, no maintenance for the first 2 years, they eliminate the temp sense system, the overflow jars and the battery temp monitor panel. They work well. http://www.securaplane.com/msbatts.html
 
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HAWK21M
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RE: Tell Me About Aircraft Batteries..

Sun Sep 28, 2008 6:46 am



Quoting A342 (Reply 40):
but these suffer from the well-known memory effect.

Pls elaborate on the term.

Quoting 411A (Reply 39):
No additional corrosion detected over time, as the battery box was replaced as soon as the overheat sensors were installed.

Thanks.

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MEL
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411A
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RE: Tell Me About Aircraft Batteries..

Sun Sep 28, 2008 12:08 pm



Quoting A342 (Reply 40):
Well, I have another question about aircraft batteries. Many types use Ni-Cd batteries, but these suffer from the well-known memory effect. How is this avoided on aircraft?

These types of ships batteries are removed from the aircraft periodically, and receive maintenance action.
It is called...deep cycling, and is essential to keep these types serviceable for long periods.
 
A342
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RE: Tell Me About Aircraft Batteries..

Sun Sep 28, 2008 4:54 pm



Quoting HAWK21M (Reply 42):
Pls elaborate on the term.

wikipedia gives a good explanation:

"Memory effect, also known as lazy battery effect or battery memory, is an effect observed in nickel cadmium rechargeable batteries that causes them to hold less charge. It describes one very specific situation in which certain NiCd batteries gradually lose their maximum energy capacity if they are repeatedly recharged after being only partially discharged. The battery appears to "remember" the smaller capacity. [1] The source of the effect is changes of the characteristics of the underused active materials of the cell. True memory effect can be reset by a few normal discharge/charge cycles. The term is commonly applied to almost any case in which a battery appears to hold less charge than was expected. Some of these cases are due to irrevesible changes in the cells due to internal short-circuits, loss of electrolyte or reversal of cells."

Quoting 411A (Reply 43):
These types of ships batteries are removed from the aircraft periodically, and receive maintenance action.
It is called...deep cycling, and is essential to keep these types serviceable for long periods.

So basically this means that as long as a Ni-Cd battery is installed, it is regularly subject to capacity loss, especially when you opts to use ground power instead of the battery/APU. That sucks. Why do large aircraft use Ni-Cd in the first place? As noted above, lead acid batteries do not have this problem, and they've been around since 1859. Hopefully the A380 and 787 batteries (both use Li-Ion) will prove themselves in service, setting a trend for other aircraft to follow.
Exceptions confirm the rule.
 
411A
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RE: Tell Me About Aircraft Batteries..

Sun Sep 28, 2008 5:07 pm



Quoting A342 (Reply 44):
Why do large aircraft use Ni-Cd in the first place? As noted above, lead acid batteries do not have this problem, and they've been around since 1859. Hopefully

The primary reason is, as the NiCad battery loses capacity (amp/hours) it nevertheless retains a constant voltage over this period in service...and if removed from the aircraft for periodic servicing, proves entirely superior is service with most turbine engine powered aircraft.

Good for example, if all generators trip offline...constant voltage to standby/emergency power circuits, until a landing can be made.
Also, for APU starting while airbourne.
 
brons2
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RE: Tell Me About Aircraft Batteries..

Mon Sep 29, 2008 2:53 am



Quoting 411A (Reply 39):

Thermal runaway...VERY nasty business.

Yes. This is one troubling thing about Li-Ion, the thermal runaway characteristics are very undesirable as compared to other battery types. They can get away from you pretty quickly. I used to work in the engineering labs of a major computer manufacturer everyone has heard of and we have sizzled a few laptops in testing before due to Li-Ion thermal runaway. The early ones were downright dangerous, and there have been quite a few recalls over the years.

I can't imagine controlling it on a much larger scale, like in an aircraft. Although, the Prius seems to do ok so maybe that is a good sign. The technology is supposed to have improved such to the point that it is much less of a risk. I hope so.
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airbatica
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RE: Tell Me About Aircraft Batteries..

Mon Sep 29, 2008 3:49 am



Quoting Brons2 (Reply 46):
I can't imagine controlling it on a much larger scale, like in an aircraft. Although, the Prius seems to do ok so maybe that is a good sign. The technology is supposed to have improved such to the point that it is much less of a risk. I hope so.

IIRC, the Prius (as delivered from the dealer) uses a NiMH battery pack.

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