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battery pack lifespan?

Old 05-21-2003, 10:54 PM
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hollewud7
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Default battery pack lifespan?

I am currently building my extra 300s 4 (GP). I am using all new equipment besides the reciever and battery pack. I know the reicever is ok but I am wondering how good thepack is. The pack was in a plane that I only used basiclly one year. Thu there is not a lot of time on the pack (maybe 30 -50 flights) The one thing I am worried about is the pack is about 4 years old. How long can they be good? It didnt sit for years but was probably charged a few times the first year anda few in the years up unti I flew it all one summer. My question is is it ok to use now?
Old 05-22-2003, 12:23 AM
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JDHammer
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Default battery pack lifespan?

Hi hollewud7,
I'm not one of the experts here but I have used nicads in my RC planes for the last 23 years which gives me some credibility. I've had one pack last 10 years, many that have lasted over 4 years and many that have lasted less than one year. In thousands of flight I have never been burned by the batteries (knock on wood) and my simple formula is to use a good cycler and use it often. When the capacity goes down,or even if the charging and discharging characteristics change from what you are used to, I take it out of the airplane and do further tests on it.
I do consider the age of the battery but only as a secondary consideration.
Old 05-22-2003, 12:24 AM
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z11355
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Default battery pack lifespan?

seems to me like unless you can cycle
it and *know* what the pack is doing,
then spending all the time and effort
on this project and then 'saving' a few
$$ on a battery pack is quite the
penny-wise pound-foolish idea.
Old 05-22-2003, 12:31 AM
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theox
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Default battery pack lifespan?

Go here:

http://www.rcbatteryclinic.com/

read this:

Ni-Cd Life, What can I expect from my R/C packs?
Old 05-22-2003, 12:11 PM
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Red Scholefield
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Default Cumulative faiure rate of Ni-Cds

Here is what you can expect of a 4 cell Ni-Cd pack in the way of failure rates.

Fairures Weeks
1.00% 123.1
2.00% 146.6
3.00% 162.5
4.00% 174.8
5.00% 185.1
6.00% 194.0
7.00% 201.9
8.00% 209.0
9.00% 215.5
10.00% 221.6
11.00% 227.2
12.00% 232.5
13.00% 237.6
14.00% 242.4
15.00% 246.9
16.00% 251.3
17.00% 255.5
18.00% 259.6
19.00% 263.5
20.00% 267.3
21.00% 271.0
22.00% 274.6
50.00% 354.9

Bottom line - half of your packs will have failed after 6.7 years
This is at an average temperature of 73 degrees F

Raise this to 90 degress F and 50% will have failed after 3.1 years with 1% failure in 1 year.
Old 05-22-2003, 12:53 PM
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STUKA BARRY
 
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Default battery pack lifespan?

HEY RED, I WENT TO TEST FLY MY STUKA FOR A MAJOR AIRSHOW THIS WEEKEND IN PAX RIVER MD. I CHARGED THE BATTERY AS NORMAL, LIKE I ALWAYS DO. I FILLED THE TANK, AND STARTED MY NORMAL RANGE CHECK ROUTINE. I ALWAYS RANGE CHECK WITH ENGINE OFF FIRST THEN START THE ENGINE AND RANGE CHECK AGAIN. THE CARB ON MY G-62 WAS FILLED WITH CRAP. IT WOULD NOT RUN RIGHT. GO RICH THEN LEAN, BLA, BLA. AFTER A SHORT PERIOD OF TIME IT STARTED TO RUN REAL FUNNY. THE THROTTLE WAS SURGING THEN THE ENGINE QUIT. I HAD NO RADIO INPUT. NO FLIGHT CONTROLS WOULD MOVE. I CHECKED THE BATTERY AND IT REGISTERED "DEAD". I REMOVED THE BATTERY FROM THE PLANE AND THE DATE ON IT (I ALWAYS DATE MY BATTERIES THE DAY I FIRST INSTALL THEM) SAID 03/01/01. I DONT FOOL WITH BATTERIES IF THEY DO ANYTHING FUNNY AT ALL I REPLACE THEM. A $30.00 BATTERY IS CHEAPER THAN A $2500.00 STUKA. I USAULLY REPLACE BATTERIES AFTER FOUR YEARS ANYHOW, BUT THIS ONE HAD ANOTHER YEAR TO GO. HAVE YOU COME ACROSS THIS PROBLEM BEFORE? I WAS ABOUT 2 MINUTES AWAY FROM A TOTAL DISASTER. I GUESS THE ENGINE WAS TELLING ME SOMETHING WAS WRONG AND DONT TAKE-OFF. I HAVE NEVER HAD THIS PROBLEM IN 22 YEARS OF RC.
Old 05-22-2003, 02:54 PM
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KJohn
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Default battery pack lifespan?

hollewud7

I would strongly recommend that you have your packs charged and then discharged a couple of times (cycled) in order to determine if the capacities of the various battery packs (receiver and transmitter) are acceptable. This is the only way to know for sure if the batteries are acceptable for your purposes. Maybe you can find a club in your area and contact a member that can do the cycling for you. It is possible that the batteries will not hold their rated capacity, in which case you might make only two flights then have an accident due to batteries. Even if you purchase a brand new battery pack it should be cycled and tested for capacity as even new packs could have a problem. When you learn about batteries you realize how important it is to run dependable tests on them once a month or once every two months.
Old 05-22-2003, 04:36 PM
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Red Scholefield
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Default battery pack lifespan?

Originally posted by STUKA BARRY
HEY RED, I WENT TO TEST FLY MY STUKA FOR A MAJOR AIRSHOW THIS WEEKEND IN PAX RIVER MD. I CHARGED THE BATTERY AS NORMAL, LIKE I ALWAYS DO. I FILLED THE TANK, AND STARTED MY NORMAL RANGE CHECK ROUTINE.
I didn't see you mention checking the battery voltage with the system on. I suspect that you lost a cell (shorted) which would give you exactly the symptoms you state.
Old 05-23-2003, 12:18 PM
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STUKA BARRY
 
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Default battery pack lifespan?

HEY RED, EDUCATE ME. HOW DO YOU CHECK VOLTAGE WITH THE RX TURNED ON? I THOUGHT I MIGHT HAVE LOST A CELL, BUT I'M NO SPARK CHASER. DONT MUCH LIKE SPARK CHASING ON FULL SCALES, BUT SOMETIMES I HAVE TO. AVIONICS IS'NT MY FAVORITE THING.
Old 05-23-2003, 12:44 PM
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Red Scholefield
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Default battery pack lifespan?

Originally posted by STUKA BARRY
HEY RED, EDUCATE ME. HOW DO YOU CHECK VOLTAGE WITH THE RX TURNED ON? I THOUGHT I MIGHT HAVE LOST A CELL, BUT I'M NO SPARK CHASER. DONT MUCH LIKE SPARK CHASING ON FULL SCALES, BUT SOMETIMES I HAVE TO. AVIONICS IS'NT MY FAVORITE THING.
Just plug a pigtail into any empty receiver channel and measure with a voltmeter with plug to match.

Easier way is to use a Voltwatch from Tower Hobbies.

Alternative, use a loaded voltmeter plugged into the charge jack, this does not measure with receiver on but it does simulate the load.
Old 05-25-2003, 10:03 PM
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STUKA BARRY
 
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Default battery pack lifespan?

HEY RED, I DO HAVE THE HOBBICO DIGITAL VOLTMETER WHICH SIMULATES A SERVO LOAD. IT REGISTERED NOTHING AFTER THE FLIGHT CONTROLS FAILED TO MOVE. ITS REGISTERING 5.2 ON THE NEW BATTERY THAT I CHARGED THREE DAYS AGO SO I FEEL SAFE FLYING THE STUKA NOW.
Old 05-27-2003, 02:25 PM
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hebertjj
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Default Hey Stuka!

Yo!
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Old 05-27-2003, 02:28 PM
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hebertjj
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Default battery pack lifespan?

Great data, Red! Are you going to post this in the battery clinic (or did I miss it )? If not I'm going to have to archive it in my doc and probably lose it.

Thanks,
Joel
Old 05-27-2003, 04:13 PM
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Red Scholefield
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Default battery pack lifespan?

Originally posted by hebertjj
Great data, Red! Are you going to post this in the battery clinic (or did I miss it )? If not I'm going to have to archive it in my doc and probably lose it.

Thanks,
Joel
I had not planned on putting it on the battery clinic web site... but it you want the spread sheet program *.xls (microsoft excel) let me know.
Old 05-29-2003, 01:30 AM
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elevator_up
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Default Cell life probabilities

Red, this is great data, and gives me an order of magnitude on longevity that I did not have before. Are the percentages based on a formula that can be amended by battery type, size & number of cells ? I'd be interested in the .xls. Please e-mail me at your convenience.
Old 05-29-2003, 10:15 AM
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Red Scholefield
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Default Re: Cell life probabilities

Originally posted by elevator_up
Red, this is great data, and gives me an order of magnitude on longevity that I did not have before. Are the percentages based on a formula that can be amended by battery type, size & number of cells ? I'd be interested in the .xls. Please e-mail me at your convenience.
It is based on the kind of separator used, nyon or polypropylene and the average temperature the pack is exposed to.

Will try to send .xls file back channel for you to play with, but you will have to send me your e-mail address. You have it blocked on this forum.

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