HOW TO SIZE THE BATTERY BASIC INFORMATION AND TUTORIALS

You might get the idea that you can connect hundreds, or even thousands, of cells in series and obtain batteries with fantastically high EMFs. Why not put 1,000 zinc-carbon cells in series, for example, and get 1.5 kV?

Or put 2,500 solar cells in series and get 1.25 kV? Maybe it’s possible to put a billion solar cells in series, out in some vast sun-scorched desert wasteland, and use the resulting 500 MV (megavolts) to feed the greatest high-tension power line the world has ever seen.


There are several reasons why these schemes aren’t good ideas. First, high voltages for practical purposes can be generated cheaply and efficiently by power converters that work from 117-V or 234-V utility mains.

Second, it would be difficult to maintain a battery of thousands, millions or billions of cells in series. Imagine a cell holder with 1,000 sets of contacts. And not one of them can open up, lest the whole battery become useless, because all the cells must be in series. (Solar panels, at least, can be permanently wired together. Not so with batteries that must often be replaced.)

And finally, the internal resistances of the cells would add up and limit the current, as well as the output voltage, that could be derived by connecting so many cells in series. This is not so much of a problem with series-parallel combinations, as in solar panels, as long as the voltages are reasonable.

But it is a big factor if all the cells are in series, with the intent of getting a huge voltage. This effect will occur with any kind of cell, whether electrochemical or photovoltaic.

In the days of the Second World War, portable two-way radios were built using vacuum tubes. These were powered by batteries supplying 103.5 V. The batteries were several inches long and about an inch in diameter.

They were made by stacking many little zinc-carbon cells on top of each other, and enclosing the whole assembly in a single case. You could get a nasty jolt from one of those things. They were downright dangerous!

A fresh 103.5-V battery would light up a 15-W household incandescent bulb to almost full brilliance. But the 117-V outlet would work better, and for a lot longer.

Nowadays, handheld radio transceivers will work from NICAD battery packs or batteries of ordinary dry cells, providing 6 V, 9 V, or 12 V. Even the biggest power transistors rarely use higher voltages. Automotive or truck batteries can produce more than enough power for almost any mobile or portable communications system.

And if a really substantial setup is desired, gasoline-powered generators are available, and they will supply the needed energy at far less cost than batteries. There’s just no use for a mega battery if a thousand, a million, or a zillion volts.

NICKEL - CADMIUM CELLS AND BATTERIES BASIC INFORMATION

You’ve probably seen, or at least heard of, NICAD cells and batteries. They have become quite common in consumer devices such as those little radios and cassette players you can wear while doing aerobics or just sitting around. (These entertainment units are not too safe for walking or jogging in traffic.

And never wear them while riding a bicycle.) You can buy two sets of cells and switch them every couple of hours of use, charging one set while using the other. Plug-in charger units cost only a few dollars.

Types of NICAD cells
Nickel-cadmium cells are made in several types. Cylindrical cells are the standard cells; they look like dry cells. Button cells are those little things that are used in cameras, watches, memory backup applications, and other places where miniaturization is important.

Flooded cells are used in heavy-duty applications and can have a charge capacity of as much as 1,000 Ah. Spacecraft cells are made in packages that can withstand the vacuum and temperature changes of a spaceborne environment.

Uses of NICADs
There are other uses for NICADs besides in portable entertainment equipment. Most orbiting satellites are in darkness half the time, and in sunlight half the time. Solar panels can be used while the satellite is in sunlight, but during the times that the earth eclipses the sun, batteries are needed to power the electronic equipment on board the satellite.

The solar panels can charge a set of NICADs, in addition to powering the satellite, for half of each orbit. The NICADs can provide the power during the dark half of each orbit. Nickel-cadmium batteries are available in packs of cells.

These packs can be plugged into the equipment, and might even form part of the case for a device. An example of this is the battery pack for a handheld ham radio tranceiver. Two of these packs can be bought, and they can be used alternately, with one installed in the “handie-talkie” (HT) while the other is being charged.

NICAD neuroses
There are some things you need to know about NICAD cells and batteries, in order to get the most out of them. One rule, already mentioned, is that you should never discharge them all the way until they “die.” This can cause the polarity of a cell, or of one or more cells in a battery, to reverse.

Once this happens, the cell or battery is ruined. Another phenomenon, peculiar to this type of cell and battery, is called memory. If a NICAD is used over and over, and is discharged to exactly the same extent every time (say, two-thirds of the way), it might start to “go to sleep” at that point in its discharge cycle.

This is uncommon; lab scientists have trouble forcing it to occur so they can study it. But when it does happen, it can give the illusion that the cell or battery has lost some of its storage capacity. Memory problems can be solved. Use the cell or battery almost all the way up, and then fully charge it. Repeat the process, and the memory will be “erased.”

NICADS do best using wall chargers that take several hours to fully replenish the cells or batteries. There are high-rate or quick chargers available, but these can sometimes force too much current through a NICAD.

It’s best if the charger is made especially for the cell or battery type being charged. An electronics dealer, such as the manager at a Radio Shack store, should be able to tell you which chargers are best for which cells and batteries.

MINIATURE CELLS AND BATTERIES BASIC INFORMATION AND TUTORIALS

In recent years, cells and batteries—especially cells—have become available in many different sizes and shapes besides the old cylindrical cells, transistor batteries and lantern batteries. These are used in watches, cameras, and other microminiature electronic gizmos.

Silver-oxide types
Silver-oxide cells are usually made into button-like shapes, and can fit inside even a small wristwatch. They come in various sizes and thicknesses, all with similar appearances.

They supply 1.5 V, and offer excellent energy storage for the weight. They also have a flat discharge curve. The previously described zinc-carbon and alkaline cells and batteries have a current output that declines with time in a steady fashion


Silver-oxide cells can be stacked to make batteries. Several of these miniature cells, one on top of the other, might provide 6 V or 9 V for a transistor radio or other light-duty electronic device. The resulting battery is about the size of an AAA cylindrical cell.

Mercury types
Mercury cells, also called mercuric oxide cells, have advantages similar to silver-oxide cells. They are manufactured in the same general form. The main difference, often not of significance, is a somewhat lower voltage per cell: 1.35 V. If six of these cells are stacked to make a battery, the resulting voltage will be about 8.1 V rather than 9 V.

One additional cell can be added to the stack, yielding about 9.45 V. There has been some decrease in the popularity of mercury cells and batteries in recent years. This is because of the fact that mercury is highly toxic.

When mercury cells and batteries are dead, they must be discarded. Eventually the mercury, a chemical element, leaks into the soil and ground water. Mercury pollution has become a significant concern in places that might really surprise you.


Lithium types
Lithium cells have become popular since the early eighties. There are several variations in the chemical makeup of these cells; they all contain lithium, a light, highly reactive metal. Lithium cells can be made to supply 1.5 V to 3.5 V, depending on the particular chemistry used. These cells, like their silver-oxide cousins, can be stacked to make batteries.

The first applications of lithium batteries was in memory backup for electronic microcomputers. Lithium cells and batteries have superior shelf life, and they can last for years in very-low-current applications such as memory backup or the powering of a digital liquid-crystal-display (LCD) watch or clock.

These cells also provide energy capacity per unit volume that is vastly greater than other types of electrochemical cells.

Lithium cells and batteries are used in low-power devices that must operate for a long time without power source replacement. Heart pacemakers and security systems are two examples of such applications.

RECOMBINING SEALED LEAD-ACID BATTERIES BASIC INFORMATION AND TUTORIALS

There are two categories of sealed lead-acid cell. These are the non-recombining or partially recombining type, such as those manufactured by Sonnenschein and by Crompton-Parkinson Ltd, and the fully recombining types, as manufactured by the General Electric Company and by the Gates Rubber Company. The fully recombining types are also produced in the UK under licence by Chloride Energy Ltd under the trade name Cyclon.

Particularly towards the end of charge and when being overcharged, the sulphuric acid electrolyte in lead-acid batteries undergoes electrolysis to produce hydrogen and oxygen.

Consequently, in service, the electrolyte level drops and the concentration of sulphuric acid increases, both of which are deleterious to battery performance and, unless attended to by periodic topping up with distilled water, will lead to the eventual destruction of the battery.

Aware of this danger manufacturers recommend a periodic topping up of the electrolyte to the prescribed mark with distilled water. The need for regular topping up has in the past limited the applications in which lead- acid batteries can be used. Manufacturers have adopted two methods of avoiding the need to top up lead-acid batteries:

1. The development of non-recombining or partially recombining batteries in which, by attention to battery design (new lead alloys for grids, etc.) and by using more sophisticated battery charging methods, gassing is reduced to a Aninimum and topping up is avoided.

2. The development of fully recombining types of battenes in which any hydrogen and oxygen produced by gassing is fully recombined to water, thereby avoiding loss of electrolyte volume.

Both methods have been used to produce a range of non-spill either partially or fully recombining sealed lead-acid batteries which are now finding an everincreasing range of applications for this type of battery.

BATTERY CHARGING REGULATOR CIRCUIT BASIC PROJECT

The circuit is capable of charging 12-V battery at up to six ampere rate. Other voltages and crrents, from 6 to 600 V and up to 300 A can be accomodated by suitable component selection.

When the battery voltage reaches its fully charged level, the charging SCR shuts off, and a trickle charge, as determined by the value of R4, continues to flow.

14 V 4 A BATTERY CHARGER/ POWER SUPPLY ELECTRONIC PROJECT DIAGRAM BASIC AND TUTORIALS

This is a basic electronic project of Battery Charger/ Power supply.


Operational amplifier A1 directly drives the VN64GA with the error signal to control the output voltage. Peak rectifier D1, C1 supplies error amplifier A1 and the reference zener. This extra drive voltage must exceed its source voltage by several volts for the VN64GA to pass full load current.

The output voltage is pulsating dc, which is quite satisfactory for battery charging,