The Lithium-Ion Battery in

Everyday Use

This article appeared in the November 1999 edition of the "USECA Express", the newsletter of the Utica Shelby Emergency Communications Association, Joe Janules, K8OEF Editor. By lsidor Buchmann, founder and CEO of Cadex Electronics Inc., in Burnaby (Vancover) British Columbia, Canada. Copyright © 1998.

A few years ago, the Nickel Cadmium (NiCd) was the only suitable battery for applications such as cellular phones, laptop computers and video cameras. Since then, new battery chemistries have emerged that provide twice the energy density. One such battery is the Lithium-ion (Li-ion). Will the Li-ion eventually replace the classic NiCd? The answer is no, at least not for now. Every invention that solves one problem creates new ones. Compared to the mature and rugged NiCd system, the Li-ion is fragile and requires a protection circuit to maintain safe operation. The load current is moderate and charging must be done according to strict standards. In addition, the Li-ion is subject to aging whether used or not. Signs of reduced performance are visible after one year; a typical service life of a Li-ion is about two years from date of manufacture.

One major advantage of the Li-ion is the absence of memory. No scheduled cycling is required to prolong the battery's life. In addition, self discharge is less than half compared to the NiCd, making the Li-ion well suited for modern fuel gauge applications.

History

Pioneering work for the lithium battery began in 1912 by G. N. Lewis but it was not until the early 1970s when the first non rechargeable lithium batteries became commercially available. Attempts to develop rechargeable lithium batteries followed in the eighties, but failed due to safety concerns.

Lithium is the lightest of all metals, has the greatest electrochemical potential and provides the largest energy content. Rechargeable batteries using lithium metal as electrode are capable of providing both high voltage and excellent capacity, resulting in etraordinary energy density. After much research during the eighties, it was found that occasional shorts from lithium dendrites would cause thermal run-away. The cell temperature would quickly approach the melting temperature of the lithium which resulted in violent reactions. A large quantity of rechargeable lithium batteries sent to Japan had been recalled in 1991 after a battery in cellular phone exploded and inflicted burns to a man's face.

Because of the inherent instability of lithium metal, especially during charging, research shifted to a non-metallic lithium battery using lithium ions from chemicals such as Lithium-Cobalt Dioxide (LiCoO2). Although slightly lower in energy density than with lithium metal, the Li-ion is safe, provided certain precautions are met when charging and discharging. In 1991, Sony commercialized the Li-ion and other manufacturers followed suit. Today, the Li-ion is the fastest growing battery chemistry in the world.

Charging the Li-ion battery

The Li-ion charger is a voltage-limiting device similar to that of the Valve Regulated Lead Acid (VRI,A) charger. The main differences of the Li-ion charger are higher voltage per cell, tighter voltage tolerance and the absence of trickle or float charge at full charge. Whereas the VRI,A offers some flexibility in terms of voltage cutoff, the manufacturer of Li-ion cells is very strict about the voltage choice. The voltage threshold of the Li-ion with the graphite electrode is 4.10V whereas the coke electrode and spinel is set to 4.20V. Tile tolerance of +/- 0.05 volts per cell.

Since higher voltage thresholds provide increased capacity, it is in the manufacturer's best interest to choose the highest voltage threshold possible without affecting safety and compromising service life. However, the higher the charge voltage, the greater cell corrosion. To minimize deterioration by corrosion, the charge current is cut off once the battery has reached full charge. Correct voltage setting should be observed when servicing Li-ion batteries on a battery analyzer. This task may be difficult because most battery manufacturers do not specify which version Li-ion is used. If the voltages are set incorrectly, the graphite cell will be slightly overcharged if allowed to reach 4.2V. Likewise, a coke cell will yield lower capacity when discharged to only 3.0V instead of 2.5V. At moderate temperature, little damage occurs when occasionally charging to a higher voltage threshold, but repeated overcharging will hasten corrosion and shorten service life.

Protection Circuit

Commercial Li-ion batteries contain several built-in protection devices. Typically, a fuse opens if the charge voltage of ally cell reaches 4.30V or the cell temperature approaches 100C (212F). In addition, a pressure switch in each cell permanently interrupts the charge current if a certain pressure threshold is exceeded, and internal voltage control circuits cut off the battery at low and high voltage points. Some batteries feature a low voltage cutoff switch which permanently disconnects the pack if a cell goes below 2.5V. This precaution is done to prohibit a recharge if a battery has dwelled in an illegal voltage state. Charging such a battery could cause lithium metal formation because the electrochemical structure of the cell has been permanently altered.

Most manufactures do not sell the Li-ion cells by themselves but make them available in a battery pack, complete with protection circuit. This precautionary procedure is understandable when considering the danger of explosion and fire if the battery is charged and discharged beyond its safe limits.

A major concern arises if static electricity, or a faulty charger manages to destroy the battery's protection circuit through the battery's contacts. Such damage often causes the solid-state switches to fuse to a permanent ON position. A battery, with fused switches can no longer be used safely. If charged beyond safe voltage limits, the battery may heat up, then bulge and in some cases vent with flame. Shorting the battery can also be hazardous.

Conclusion

The Li-ion receives good grades in performance and reliability. Billions of dollars are invested in tooling for increased production. Delivery shortages are easing and prices are becoming more affordable. As a result, more portable equipment is being fitted with the Li-ion battery.

The Li-ion has found a strong market niche with portable devices requiring long run time. Because of the aging aspect, the Li-ion is most beneficial for applications with a hectic user pattern. Where the Li-ion falls short is on high current applications and operations that require a full discharge before recharge. Typical uses that fall into this category are power tools and heart defibrillators.

Another field where the Li-ion has proven less favorable is in applications that require only occasional use. On a laptop that is mostly powered by AC, for example, the Li-ion battery ages in time without being able to deliver the full benefit. For these applications, other battery types may serve better.

The Lithium polymer systems in development are straggling to meet and surpass the performance of the L,i-ion battery. Limited cycle life and high internal resistance are the main drawbacks of today's Lithium polymer. Once mass produced, the Lithium polymer is said to be lower priced than the l,i-ion. In addition, the Lithium polymer can then be shaped into virtually any form. One day the battery may be part of the protective housing or serve as a soft carrying case.

 

 

We should be ashamed of ourselves

The following article was reprinted from the January 2000 issue of Worldradio.

(Ed. Th. is was forwarded to World-radio by Bill Pasternak, WA6ITF. "Jimmy K.", the author is unknown. How many times have you heard a new call on a repeater, and chose to ignore it because it was an unfamiliar call? We should all be ashamed of ourselves. This isn't supposed to happen in Amateur Radio.)

" I just wanted to share a little story regarding my experiences with Ham radio. Help me make a fair assessment.

"I have been a Ham for about a year now. I remember I couldn't wait to get my callsign after passing the exam, and the pride I felt with that ticket came in the mail and I could get on the air. From there, though, it went downhill quick.

"So I get on the air. Aside from one nice gentleman who chatted with me several times on a local repeater, I can't get anyone to respond. "K monitoring'' I call, over and over. Maybe I'm not getting out, I thought, but a quick grab of my HT to listen to the output of the repeater(s) I key up ensures I'm loud and clear. Nobody answers, until I call again and again and finally someone gets tired of hearing me call and decides they'll speak with a stranger. Seems that if you're not a "regular" whom everyone knows, nobody's interested in responding.

"So I figured if I got to know some of the other Hams, someone may want to talk to me. I get on the internet and find the website of the local club. It advertises a meeting that night! Great, I thought, and headed straight to the location right after work. But nobody's at the location. Must have moved, I think, so I get on the air and call. And call. And call some more on the most heavily used repeater in the metro area (1 million + population). A quick grab of my HT again confirms I'm full quieting into the repeater. Another 30 minutes of calling and a rather irritated gentleman advises that the meeting's been moved, and that he's there, but advises it's a party for the club, and reservations needed to be made in advance. Discouraged, I head home.

"Then I thought maybe I should get involved in a local Ham radio function. This was a good idea, as a leader of the local club was on the air asking for volunteers to work with them at a Christmas parade-type function in town in a couple of weeks. I cheerfully volunteered, and the man took my name and number over the air. He said he'd call soon with details when the volunteer roster was complete, but no call ever came, either on the air or by phone. So I assumed they didn't need any more help. I attended the parade with my wife and approached one of the Hams working there and attempted friendly conversation. I was told rather standoffishly that I could have helped, all I'd have to do is get a Ham license. The guy just assumed that because I didn't have wires and antennas hanging off my body, and wasn't either elderly or handicapped, I must not be a Ham.

"With my faith in Ham radio in question, I didn't get on the air for several months. Then I began traveling. Thought it would be nice to meet other Hams on the road, so at high points I would call "CQ" on 146.52 simplex. And called and called and called. After about a month of doing this daily while driving, I made a contact! The gentleman was very friendly and interesting, but told me about calling on simplex 146.52, "nobody ever monitors that anymore." I figured I'd have better luck with the CB, and sure enough I did.

Later that month I broke down on the side of the road outside of San Antonio TX. I happened to know that San Antonio has wide-area coverage on 146.94, so I keyed up the machine (again full quieting) and called CQ, then called "emergency" then "mayday."

No answer. I held down the 0 DTMF key for 5 seconds and called again-- still no answer. So I check other repeaters. The only other one I could reach was being occupied by someone who just loved to bring up the autopatch unidentified, dial numbers at random, then bring it down, over and over. Listened a little longer and found it was a kid playing with the autopatch. So I call 146.52, since I'm on an interstate (must be Hams on the road, it's a holiday weekend). I called until I was blue in the face. No response there either. So, I gave up. The CB brought a tow truck in about 5 min.

"So I guess my point is that I don't want to hear any more of the "long-timers" whining about Ham radio being a "dying breed", and that nobody in their 20-40's is interested any more. I'm a very technically competent, friendly, and personable individual, and I felt as though I had something to contribute by being involved in Ham radio. There was someone that WAS interested (me), and tried earnestly to get involved and participate, but frankly, I find more responsive, friendly, and helpful people on CB." -- Jimmy K.

 

VE Exams

by

Bob Wexelbaum, W2ILP

The FCC has adopted new rules that will change the Amateur Service licensing structure and reduce the emphasis on Morse Code. Effective in 2000 all license examinations and modifications at VE sessions will require a $6.65 administrating fee.

The much anticipated FCC restructuring report and order was released on December 30,1999. Effective April 15, 2000 applicants will only be able to be examined for three license classes: Technician - the VHF/UHF entry level; General - the HF entry level...and Extra - a technically oriented senior license. There will be only one Morse code examination speed of 5 wpm. Current Novice and Advanced Class licensees will be able to modify and renew their licenses indefinitely, however. Tech-Plus amateur licenses will be renewed as Technician class, but will retain HF operating privileges indefinitely. The FCC elected not to change the operating privileges of any class at this time.

A VEC question pool committee will decide on the content of each of three new written exams. The Tech exam and the General class exams will each contain 35 multiple choice questions. The Extra class exam will contain 50 questions.

There will be no automatic upgrades. Techs (pre-1987) who have passed 5 wpm code and element 3B will qualify for General class but must apply with proof at a VE session after April 15th.

Current Advanced Class hams who pass element 4B at a VE session before April 15th can apply for Extra class at a VE session after April 15th (by showing their CSCE). Current Tech-Plus licensees who pass element 3B at a VE session before April 15th can apply for General class at a VE session after April 15th. Current no-code Techs who pass element 3B exams before April 15, then have 1 year to pass a 5wpm code test for General.

As in the past the GARC VE team will continue to follow all FCC regulations and make VE sessions available on the second Tuesday of each month.

 

GRUMMAN AMATEUR RADIO CLUB

MINUTES OF GENERAL MEETING 1/19/00

BY Pete, N2PYV

The meeting was called to order by Pat at 6:45 PM.

This was our first meeting at the Underwriters Lab in Melville. The meeting room is very nice. Our host, Bill, N2SFT, gave some introductory remarks, explaining what UL does etc. All present introduced themselves.

TREASURER'S REPORT - Ted, KD2UB

Ted read the financial statement. Finances continue to be in good shape.

REPEATER REPORT - Gordon, KB2UB

The sale of the Haupaugue tower is not going well for Northrop Grumman. It seems that the guy wires for the tower are in a landfill that is contaminated. This scares potential buyers away.

VE REPORT Bob, W2ILP

There were four applicants. Two were new No Code Techs and two passed update exams.

WAG REPORT Bob, W2FPF

No activity.

HOUSE REPORT

Pat has had a discussion with the Northrop Grumman Insurance Dept. He was assured that all members are covered for liability at every meeting and field day by the NG insurance. We will, therefore, be able to cancel the liability insurance policy that the club has.

Pat reported that most of the property in Bethpage has been sold. Still not sure about the fate of Plant 5.

The Wednesday 20 Meter Net had four check-ins. The Sunday 40 Meter Net had about fourteen.

MEMBERSHIP:

Two applicants were approved for membership as follows:

Peter Manfre, WA2ODO, Advanced

Carmine DeVito, WA2GYX, General

 

 

PROGRAM

Bill, N2SFT, played an interesting video about the activities of the UL. He then divided the group into two parts and took them on a tour of the UL facility.

 

EDITORIAL

As you all know a program is available that allows you to read all of the CQ de WA2LQO newsletters published in 1998. As of now a program is available that will allow the user to read all of the newsletters published in 1998 and 1999.

The program is available on two flopy disks and contains all the information published in the 1998 and 1999 newsletters.

I am presently working on a program that will allow the user to read the history book published by the club (45 Years of History 1945 1989). Since this is a rather large project the finished program will be on a CDRom because of the space required. Also, it will take some time to do. It should be ready by the end of the year.

The Editor, KA2FEA