GEL CELL CARE

by

Don Rotolo-N2IRZ


This article appeared in the "NEDA Report" for September 1998, the journal of the Northeast Digital Association, Tadd Torborg-KA2DEW Editor.

There are basically only two common types of rechargeable batteries: Nickel-Cadmium cells (NiCads) and Lead-Acid cells. NiCads are usually small, as it becomes difficult to manufacture high capacity NiCad cells. Lead-Acid cells are usually used for large-power applications, such as starting a car. A special type of Acid cell uses an acid that has been gelled, kind of like soft jelly - the Gel Cell.

Regular Lead-Acid batteries use diluted Sulfuric acid as an electrolyte, in liquid form. Unfortunately, the fluid can leak out even in so-called "sealed" batteries, creating a dangerous situation. In a Gel Cell, the acid is too viscous to leak out, even if you break the battery open, increasing safety near people. This makes Gel Cells the battery of choice for battery-backed power applications. They do, however, require different care from other types of batteries.

Gel Cells are severely damaged by deep cycling, when you discharge a battery completely (or nearly so) and then recharge it. Leaving it in a discharged state, even for a week, also damages the battery. Owing to different chemical reactions, this type of treatment is actually good for NiCad cells - but fatal to Lead-Acid cells. Gel Cells are not easily repaired when they are abused, also unlike NiCads. (Too much abuse will kill ANY cell). The best conditions for a Gel Cell are a constant trickle charge, with brief periods of moderate discharge - typical battery backup requirements. Overcharging, even a little, kills any Lead-Acid cell, but is especially harmful to Gel Cells since tile electrolyte (acid) cannot move around freely, and critical areas can become devoid of the essential Sulfur ions.

A normal Lead-Acid battery has an open circuit voltage of 2.1 volts, with a 6-cell, "12" volt battery delivering about 12.6 volts. The trick to keeping the battery charged without disastrous overcharging is to only charge to about the 90% level, In real terms, that means a slow charge at about 10% of the Amp-Hour (Ah) rating. Thus, if you have a 25 Ah battery, you should design a circuit that doesn't provide more than 2.5 Amps. That will get the battery charged up fast enough, but as current drops, the voltage will probably rise. The charger will become self-limiting if you also make sure that the voltage never rises above 12.6 volts!

Now, I can see hundreds of battery cognoscenti reeling in horror at that last statement. Sure, for a full charge, the voltage must end up at about 14.4 volts - but we only want 90%, thus permitting us to leave the supply connected without damaging the battery by overcharging! There are automatic chargers available, at reasonable cost, that will bring you to 100% but not 101%, and they're great. But a cheap ham (like me) can get away with an old cube-type power supply, rescued from a calculator. And 90% will keep tile batteries happy while providing enough power.

Batteries are rated by voltage (nominal 2 volts per cell) and capacity in Amp-hours (amps times hours). Since the capacity of the battery is directly related to the discharge rate (as a percentage of the max rate), most Ah ratings are for a 20-hour period. Thus, a 20 Ah battery can provide 1 Amp for 20 Hours. I doubt, however, that it could provide 20 Amps for 1 Hour.

To select the capacity you need for your system, just multiply the average current draw by the number of hours you expect your system to operate without utility company power. Take that number, and multiply by 3, so you only discharge your batteries by 1/3 (to 60%) at most.

If you run something that may be used more heavily in an emergency without power (like a repeater), figure that into your average current rating. Better, of course, would be more battery capacity - like twice the number you just got. Not only will the batteries last much longer (due to the shallower discharge cycle), but in a REAL emergency you'll be on the air more than twice as long. By then, if your equipment is that needed, someone will have connected a portable generator. After all, 24 hours is stretching any battery backup system.

These suggestions will also work for liquid-electrolyte batteries, like car batteries, but some extra precautions are required. Batteries generate highly explosive Hydrogen gas (remember the Hindenberg?) and must be ventilated and kept away from ALL sources of ignition (like that cigarette, OM). Near people, take care that the acid can't be touched or spilled. Also, check the water regularly, even in those "sealed" batteries, and because low water is a battery's worst enemy (check your car, too). The ideal solution is to locate liquid electrolyte batteries outside, in a ventilated box that is kept warmer than -18C (0F). A charged battery won't freeze, but a discharged one will. As a second choice, keep it indoors, but put the battery in an enclosure that is vented, with a small fan, at least 2 CFM, to outdoors.

A battery backup system with Gel Cells is simple, safe and reliable. Keeping them charged is easy, if you're willing to compromise a little. The batteries are not inexpensive, but don't be fooled into buying used ones: they've probably been killed by sitting uncharged for a year in someone's basement. For more information, go to your library and ask the librarian, who will be happy to help. An engineering university library will have more of the theoretical stuff, and the ARRL Handbook has a few pages on the subject worth reading.


A NEAT IDEA - CLUB PARTS "WAREHOUSE" from TRSC Monitor

Years ago, many hams built most their own equipment. Of course many years ago most cities had several radio parts stores, and there were always the mail-order firms. Remember Allied, Lafayette and Burstein-Applebee to name just a few? Nowadays we have Radio Shack, but they offer little in the way of high frequency/high power parts. One club has done something to address this problem, they have begun their own stock of parts. Here's how they do it. This appeared in the September 1998 electronic issue of the "TSRC Monitor", the newsletter of the Twin States Radio Club, Mike Maynard-WBIGRR Editor

PLAN FOR THE MANAGEMENT AND OPERATION OF THE ELECTRONIC PARTS STOCK SERVICE FOR TWIN STATE RADIO CLUB MEMBERS.

The purpose of maintaining the parts stock is to provide a service to TSRC members for personal use for construction of Amateur Radio projects and kits or for repair of Amateur Radio gear and related equipment. The initial stock of parts is owned by Bill Burden WB1BRE, Mike Schmitt N1MS, and Matt Atwood N1RJF, and has been pooled, inventoried and stored in Bill's garage. The parts committee will consist of WBIBRE, N1MS, and N1RJF. The committee will maintain the stock of parts, review the selection and make recommendations for additional parts acquisition or elimination of obsolete parts. The committee will regularly review the rules and procedures regarding the stock and make changes as deemed necessary. The parts stock will be maintained by a committee member designated "the custodian" who will maintain and update the inventory, receive requests for parts and distribute parts to members. The custodian as appointed by the committee will be Bill, WBIBRE.

RULES AND PROCEDURES

1. These parts are being made available to club members for Amateur Radio projects, equipment repair, etc., subject to the limitations of the stock on hand. In cases where there is only a handful of a given part is available, the custodian, at his discretion, may limit the number provided to an individual depending on the size of the request.

2. The parts are made available for use by club members and are not to be sold or redistributed.

3. The stock includes both new and used parts. The committee does not guarantee the quality of the parts, nor will they accept any responsibility for problems that might result from their use.

4. The committee will, from time to time, add parts or delete parts from the inventory and the mix of parts will change with time and activity. The custodian will periodically update the inventory list posted on the TSRC web site.


5. In the startup phase of this service, any club member, excluding the three owners of the parts, may sign up for the parts service. If you are planning to build kits or use a significant number of part over the course of a 5,ear, we are asking that you sign up for an annual fee ors 10. The fee is to be forwarded to the parts committee designated for the "Parts Fund". The fee money will be used to acquire any new parts that the committee decides should be added to the stock or for other reasonable administrative costs of the program. Club members who, from time to time, need a couple of parts should contact WB1BRE with a request. There will be no charge for this service. The Custodian does reserve the right to determine the reasonableness of any request.

6. If any club member wishes to donate a stock of parts to the program, the committee will review the parts and determine a "credit" that the contributing member may draw against for the yearly fee.

7. The committee will review the program periodically or at the request of the custodian to determine if the program is working as planned and if any additional financial considerations need to be addressed- restocking specific items, procuring parts at fleamarkets, etc.

PROCEDURE

Contact the custodian via Email, US-Mail, or on the repeater and provide him with a list of parts you are requesting. The custodian is down in the Lebanon area two or three mornings each week. A schedule of transfer of parts can be worked out or you can pick the parts up at the TSRC monthly meeting.

If time or location dictate that the items need to be shipped, we will work out a shipping arrangement, with the cost to be paid by the recipient.

This is a volunteer service, so keep in mind that Bill and Dot travel periodically, and the "warehouse may be closed" from time to time.

Plans to acquire parts should include some lead time so as to minimize any delays.



The Real Problem With Windows

Having problems with your computer lately? Think you may have a virus problem? It may be something completely different - read on. Copyright 1998 The Syracuse Newspapers. Reprinted with the permission of the author, Al Fasoldt.

What's wrong with Windows? The answer might surprise you. Windows has a lot of faults and foibles, and you can't work with a PC running Windows for more than a few minutes without running into some of them. But these quirks and oddities in the way Windows behaves --- traits I've described in dozens of articles -- aren't what's wrong with Windows. They're just evidence of sloppy programming or unfinished design.

What's wrong with Windows is a deeper problem, one that can't be fixed without a complete change in the way the Windows operating system is engineered. It can be alleviated, but it can't be fixed. In their private discussions, many of Microsoft's chief programmers know about this singular failing, and they also know they need to redesign Windows to get around it. Whether they can get their bosses at the world's largest software company to approve those changes is not certain. Windows is wildly successful despite this major flaw, and Microsoft can hardly be expected to fix something that most users don't think is broken.

But Windows is broken, in a very big way. The problem can be stated simply: Adding new programs to your Windows 95 or Windows 98 PC inevitably corrupts the operating system. It can happen almost immediately or it can take many months. When this occurs, some programs won't run right and others won't run at all. Eventually, Windows itself fails to run. The term for what happens is perfectly descriptive: Windows crashes.

How this happens is easy to explain. You'll need some background first. Programs that run under Windows usually need to ask Windows for help doing certain things. A program that wants to show a message on your screen, for example, would use a common support file that shows messages. A program that needs to connect to the Internet would use another common support file to do that. These supporting files come in different forms. The most common is the Dynamically Linked Library, or DLL. The idea would seem to be sound: Common support files let Windows programmers write their software without having to reinvent everything that goes on.

But in fact the idea is fatally flawed. Nothing stops a programmer from creating an improved DLL, one that does its job faster or with less fuss, and nothing stops a programmer from messing up a DLL and calling it "improved." In either case, other programs that use the same DLL may not be able to run with the changed version. The other programs could refuse to run or they could simply crash -- or cause Windows to crash.

Add this up over many months of use, scores of newly installed programs and hundreds upon hundreds of DLLs in a typical Windows PC and you have the makings of a disaster. No other device commonly used in daily life behaves like a Windows PC. Only Windows is guaranteed to stop working if you keep using it the way it was designed to be used, as a platform for running a variety of Windows programs. The more programs you install, the quicker the inevitable end.

So what can you do? Look for a continuation of this article in the April 1999 issue.

EDITORIAL

I keep a list of all the articles published in our newsletter. Looking at the list for 1998 revealed some very interesting facts.

  1. We published a total of 28 articles for 1998.
  2. Of the 28 articles, eight were written by GARC members.
  3. The eight articles were written by five different GARC members.
  4. The five authors are:

George, N2BFY, Bob, W2ILP, Dave, KA2FEA, Jack, AD4N, and Emmett, WD4GOL

We would like to thank these authors once again and ask them to keep it coming in 1999. We also want to ask the rest of the GARC members who have a story to tell to please send it in. We will publish every article we receive. It's a great feeling to see your byline in print.

The Editor, KA2FEA

GRUMMAN AMATEUR RADIO CLUB

MINUTES OF GENERAL MEETING 2/17/99

BY TED, KD2UB

The meeting was called to order by Gordon KB2UB at 5:00PM. Gordon was substituting for Pat who was on vacation and yours truly, KD2UB, was substituting for Pete N2PYV who was also on vacation. Hurry back Pete!

TREASURERS REPORT:
Ted, KD2UB

I read the financial report and reminded everyone that the 1999 dues are due.


VE REPORT:
Bob, W2ILP

Bob reported that there was one applicant who unsuccessfully took the
20 WPM code test. There was a short discussion regarding whether call signs should be posted in the news letter for successful applicants. It was suggested that it be left up to the successful applicant decision.


REPEATER REPORT:
Gordon, KB2UB

Gordon stated that Bill is continuing work on the controller for the 145.330 repeater.

HOUSE REPORT:
Zak, WB2PUE

Zak stated that there was a good turnout on the Thursday 2 meter and the Wednesday 20 meter nets.

NEW BUSINESS:

We were fortunate to have two guest speakers at the meeting. The first presentation was given by John Caruso who represented East End Aircraft L.I. Corporation. East End Aircraft is the group that is developing Grumman Memorial Park which has been given Museum status. John brought a short video of F-14 aircraft #134 as it made its last flight past the Bethpage complex on it's way to Gabreski Airport in West Hampton Beach. John also had photos of the aircraft being towed from Westhampton Beach to it's final location at Grumman Memorial Park. Aircraft #134 made it's first flight on July 6, 1979. For more information they can be contacted at 1-888-4GRUMMAN or you can visit their web site at http://www.grummanpark.org.
The second speaker was George Tranos N2GA who is the ARRL section manager for New York Long Island. George spoke of his role as section manager which included the management of programs like ARES and Technical Specialists which are provided by the ARRL as a courtesy. He also spoke of the benefits of ARRL membership. Some of these include Preservation of frequencies, QSL Bureau's and Members only web site. The ARRL also provides an E-MAIL forwarding service which by signing up will allow you to have mail sent to YOUR_CALL@arrl.net, which will then forward it to your E-mail provider of choice. The ARRL Hudson division also has two web addresses. The Hudson division site is www.arrlhudson.org for information pertaining to New York City and Long Island use
www.arrlhudson.org/nli.
Finally we had a short video put together by Bob W2ILP and Dave AB2EF. It showed some of last years Field Day at the Islip Grange. This video was also very good. It also had a few minutes of the Smithsonian Air and Space museum.