Alkaline Batteries

Alkaline Battery
Battery
Battery Pack
Burglar-Alarm- Batteries
Capacity
Cell
Charging
Current
Disposal
Electrodes
Electrolyte
Fish
Fuel Cell
Hearing-Aid-Batteries
Internal-Resistance
LeClanche
Li-Ion Batteries
Lithium
Lithium Coin or Button Cells
Mercury Battery
Memory-Effect
Mercury
NiCd
NiMh
Parallel
Primary
Replacing Batteries
Secondary
Self- Discharge
Series
Sealed Lead-Acid Batteries
Tag
Temperature
UPS
Vent
Voltage
Watch Batteries
Zinc-Air

Battery

A device for making or storing electricity chemically. Electricity is a form or energy that is easy to control, convenient to use but difficult to store.

 A can of petrol contains 10,000 times the energy of a car battery. Hence the difficulty in making an electric car with a good performance.

Battery Pack

A rechargeable pack of batteries that can be clipped and unclipped to a battery-driven tool.

It is usually possible with reasonable ingenuity to open a battery pack and replace the cells inside.

Burglar Alarm Batteries

Most burglar alarms contain a battery as back-up in case the electricity supply is cut off. This is usually a Sealed Lead Acid Battery wired so that it is automatically recharged.

It will need replacing every 5/10 years.

Capacity

This is stated as the size of current (amps) that the battery will produce over a rated time (hours).

Measured in mAh, (milliamps x hours) or, 1000 times bigger Ah, (Amp x hours) .

This rating is usually lower if a battery is asked to produce a large current (i.e. if the battery has to work fast it will usually produce a little less useable energy).

Note that 10 Ah at 12 volts is twice the energy of 10 Ah at 6 volts. The measure of energy stored by a battery is Volts x Amps x Hours or Watt.hours.

Cell

Charging

Charge batteries with a DC current, positive terminal to positive terminal. The voltage must be greater than the battery or battery pack voltage. The current must be limited and the current cut off when the battery is fully charged.

Full charge is sensed either by a rise in voltage, a rise in resistance or a rise in temperature.

Battery chargers are designed to supply a suitable current for the batteries with which they where designed to work.

Unless chargers are labeled otherwise, remove the battery after 16 hours.

More sophisticated chargers will switch to a trickle when they sense the battery is fully charged. This is fine for Lead-Acid batteries but NiCd and NiMh should not be left on ‘maintenance’ charge for more than a few days.

As a rule of thumb, the charging current is one eighth of the Ah (in Amps) or mAh (milleamps) rating of the battery. A full charge takes about 1.4 times the label capacity.

E.g. NiMh Battery 1800mAh capacity

Charging current     1800 divided by 8 = 225 mA

Charging time          1800 divided by 225 x 1.4 = 11.2 hours

At no time should the temperature rise much beyond blood heat.

Current

The rate at which (a volume of) electricity moves through a (pipe) conductor. Measured in Amps.

The potential is measured in (height) volts.

The Voltage (or height) difference is a measure of how painful the shock (or how hard the knock is if you fall.)

With batteries, unless it is a long series, the voltage is too small to feel but the current is often large. A torch bulb takes 10 times the current of a domestic light bulb. Therefore the connections have to be more than 10 times as good, as any weakness makes a much bigger loss due to the low voltage to start with.

Clean contacts with a pencil rubber, a little Meths if necessary. Abrasive paper is a last resort as the contacts will originally have been plated and the exposed metal will quickly corrode.

If you are faced with a bad contact and are willing to try some humble botching, reform the contact by 'tinning' with solder. It works to a reasonable degree - usually.

Due to the high currents, joints - and soldered joints - must be good.

Wires must be short and heavy.

Disposal

Never burn any battery. It may explode, it will release caustic electrolyte, and it may distribute harmful metal oxide particles.

Batteries containing:

Lead

Silver

Cadmium

Mercury

must have special disposal.

Reputable scrap metal dealers will often accept Lead batteries.

Lithium batteries containing more than 0.5gram of Lithium metal (larger than sold by LowCostBatteries) present a special hazard.

Alkaline, NiMh, Zinc-Air, small Li-ion and Lithium coin cells, and conventional torch batteries can go in domestic waste in the US.

Electrodes

The raised Positive pip on a torch battery is connected to the battery Cathode; the flat end is connected to negative Anode.

In a Lead-Acid battery -car battery- Lead is the anode and acid -sulfuric acid, battery acid- the electrolyte. Lead Dioxide is the cathode.

In a NiCd, Nickel-Cadmium, battery Nickel is the anode and Cadmium the cathode.

Electrolyte

The conducting stuff between the 2 electrodes of a battery.

Usually a bit of water and a lot of nasty chemicals. In a dry cell to make things civilized, the electrolyte is made into a paste that won’t pour, absorbed onto a mat and then sealed in a container. Don’t puncture the container.

Fish

Fish are very sensitive to low voltages. This fact is used in electric fishing. 6 volts is lethal to a large fish. Aquarium owners be warned.

Fuel Cell

A battery that makes electric current from mechanically or continually replaced electrodes. E.g. Hydrogen/ oxygen cells proposed for electric cars. Not generally available off-the-shelf.

Instead of burning the fuel to make heat, the fuel cell makes electricity.

Hearing Aid Batteries

 In some hearing aids you can also use Silver-Oxide batteries. Silver-Oxide batteries are more expensive and have less capacity but they don’t self-discharge. If you use a hearing aid only occasionally, they might be worth considering.

By international agreement the size of hearing aid batteries is identified by the color of the self adhesive tab.

Internal Resistance

When a battery is connected to a circuit to do work, the current in the circuit is in inverse proportion to the resistance of the circuit plus the internal resistance of the battery. This can lead to the batteries becoming warm. If they become hot - any more than blood heat -switch off! They are being asked to do too much work.

LeClanche Battery

Zinc-Carbon batteries. Pre Alkaline torch batteries. In the lofts of old house there are often open topped glass jars that used to have a carbon and zinc rod with ammonium chloride solution as an electrolyte, to make a wet cell battery that powered the door bell. 1.5 volts.

Still made as a dry battery.

Li-Ion Batteries

Rechargeable batteries often seen in mobile phones.

3.6 volts per cell.

Lightweight, high capacity, believed memory free.

Relatively high price. Not that much difference in capacity for the same volume as NiMh, but significantly lighter.

Li-Ion batteries can be 'Top Up' charged- recharged at any convenient time, without waiting for the battery to be completely discharged.

For storage- store them as they are and allow them to self discharge slowly. Recharge them fully again when you want to use them.

Lithium

The third element, after Hydrogen and Helium. This position at one of the extremes gives it some interesting properties. It makes very good batteries but put water on it and you’ll start a fire!

Very different types of battery are made containing Lithium; some are rechargeable some are not; some are safe, some are not.

Lithium batteries sold by LowCostBatteries.com (and other general distributors) are safe, used properly. (There are industrial Lithium batteries that need special handling, transport and storage – briefly, these contain more than 0.5gram of metallic lithium per cell)

Lithium Coin or Button Cells

LowCostBatteries.com sell Lithium-Manganese Dioxide coin cells. Zinc-Manganese Dioxide -Alkaline- cells are made in the same sizes. The Lithium cells have a larger capacity and voltage. Often interchangeable. 

Not rechargeable. Never try to recharge.

3 to 3.6 volts nominal per cell.

Less than 0.5 grams Lithium per cell.

Probably inside the key fob that lets you into your car.

Better tolerance of temperature extremes than other domestic batteries. -50 Deg. C to +70 Deg. C.

Long shelf life -10years+

Long life in low drain service -in your key fob.

Magnesium Battery

Magnesium batteries are used in sea going safety equipment. They are made without an electrolyte. When immersed in sea water, the salty water acts as an electrolyte and they produce power. They have a good, but finite, shelf life even in humid conditions. Once activated they must be replaced.

Memory Effect

Some rechargeable batteries are said to have a memory. If they are part-used and recharged before the whole charge is used up, they ‘remember’ this and next time will only use that part of their capacity. Therefore part of their capacity is lost. This is the theory, it is much debated.

NiCd and NiMh batteries are said to suffer from memory effect.

NiCd and NiMh batteries prefer complete cycles; fully charge then use until empty, do not recharge before storage - allow them to self-discharge during storage.

In the real world, either of these batteries will accept less than the ideal and provided that they are recycled completely, full to empty, reasonably often they will put up with what comes in between.

NiMh batteries have less memory effect than NiCd.

In my workshop, where batteries are treated as workhorses, with only a moderate amount of care, NiCd batteries out-last NiMh batteries. This is because NiCd batteries under reasonable conditions, will take more charge/discharge cycles.

Mercury

Good batteries have been made using Mercury. These are not now in general use, because of potential pollution. Silver-Oxide or Zinc-Air cells make good or superior alternatives.

NiCd

Nickel-Cadmium batteries. Rechargeable. The archetype power tool battery. Due to the Cadmium content this battery must be disposed of safely.  NiCd batteries have gained a bad reputation for their Memory Effect (wrongly or over-emphasized in my opinion), which can reduce their voltage with age.

NiCd batteries prefer to be charged when they show a drop in power (to over-discharge a battery pack risks ‘voltage reversal’, of the weakest cell).

Store as they are, and recharge before use.

NiCd batteries self-discharge. They lose about 40% of their charge in 4 weeks.

NiCd batteries have a low internal resistance:

    They can deliver a high current

    They don’t overheat easily in use

    They can be charged quickly.

Used sensibly they have a life span twice that of NiMh or Li-ion batteries.

1.2 volts per cell, reasonably constant over the discharge cycle.

NiMh

Nickel Metal Hydride. In some ways a successor to NiCd batteries, in some ways still inferior.

• No special disposal necessary

• Increased capacity

• Less ‘memory effect’

Slower charging - a Fast NiCd charger, one of less than 8 hours is generally unsuitable.

Don’t recharge until the power begins to fall.

Store discharged.

Parallel

If a number of similar cells are connected together positive to positive, negative to negative, the voltage will be the same as a single cell and the capacity to deliver current will be the sum of the total - in theory.

In practice, it is much better to use a bigger capacity single cell.

NiCd, NiMh and Lithium cells should not be connected in parallel.

See Series

.

Primary Battery

Not rechargeable e.g. Traditional torch battery. Connecting to a charger may be hazardous.

Replacing Batteries

Always replace all the batteries in a circuit if you replace any. Never connect different types of battery together. The stronger batteries can reverse the polarity of the weaker. There is a small risk of rupturing a cell.

Check the terminals are clean and making good contact.

Put the batteries in the right way round.

Raised Pip to the + or red terminal.

Nose to tail, the pip of one battery to the base of the next.

Often a coil spring pushes on the base of the battery and a flat contact connects to the pip.

Sealed Lead Acid Batteries

2 .0 volts per cell

The Sealed Lead Acid battery is the traditional wet cell car battery, re-designed as a dry battery. The electrolyte is gelled and absorbed onto a glass fiber mat, and the areas of the anode and cathode greatly increased. Although the cost of manufacture is higher, sealed lead acid batteries or “gel cells” have a longer life, higher capacity and are safer than wet cells.

These batteries must be stored in a charged condition, they self-discharge at a moderate rate. Therefore they should be re-charged at least once a year to remain in good condition, even if only stored.

If the temperature is raised - garden shed in summer - recharge more frequently.

SLA batteries can be used anyway up, but charge upright. See Vent

You can replace a wet Lead Acid battery with a Sealed Lead Acid battery, of similar capacity without altering the circuit or charging circuit.

Use with advantage in all small vehicles including sports vehicles.

Freeze/ thaw stable, withstands lower temperatures better fully charged.

Car Batteries and to a lesser extent SLA batteries can evolve Hydrogen and Oxygen whilst being charged. These gases form an explosive mixture. Allow ventilation to batteries whilst charging.

Secondary battery

Rechargeable. e.g. NiMh Mobile Phone battery. (Nickel/Metal Hydride). The action of the battery is reversible; connected to a light bulb it makes light and discharges; connected to a charger it recharges-- the charger forces the chemical reaction to go the other way.

Self Discharge

Batteries, stored, unused, lose their charge (age), slowly with time.

The rate of self-discharge depends on the type of battery. Alkaline batteries and most primary batteries have a good shelf life - they self-discharge very slowly.

The rate of self-discharge rises rapidly with temperature, the ideal storage temperature is between 4 and 15 Deg. centigrade.

These are guide figures, for the loss of charge in 1 month at 20 Deg. C.

Series

Cells are often connected in series to increase the voltage. Negative electrode is connected to positive electrode to make a daisy chain of cells, a battery of cells (hence the name battery); we would now say battery pack.

The cells should always be similar cells. Never replace one cell in a series, always the lot.

The battery pack is only as good as the weakest cell.

See Parallel

Tag

When rechargeable cells are assembled into a battery pack, they are connected in series by tags welded to the battery. In large-scale production the connections may all be welded without any soldered joints. This gives joints with the lowest resistance. On a small scale, or when the currents are lower or in repair work soldering to tags is much easier than soldering on to a battery.  

Temperature

Common batteries like the same temperatures as humans. They won’t work well in low temperatures. High temperatures shorten their life.

This factor needs careful consideration if batteries are going to be relied upon in an emergency.

Store at max. 25C, preferably less. A camera battery in a black case in the sun or a lead-acid battery in a greenhouse will have a shorter life.

Special batteries are made for other temperature ranges. Lithium batteries perform best of the common batteries.

The risk of a power tool battery pack, used on a building site, having a shorter life increases as the battery becomes bigger. As the tool is worked hard, the battery temperature rises. Working at elevated temperatures is bad for the battery. The cells are packed close together with no room for the heat to escape. NiMh cells with their higher internal resistance are more at risk than NiCd cells.

UPS

Uninterruptible Power Supply Units:

     keep a computer and its data safe and running what ever happens to the power supply - lightning, voltage drop or droop, surge, fuse blown or supply cut

     can be programmed to save current work and close down after a set number of minutes

     protect the phone and computer from surges induced by lightning in the phone line

     correct the power from a local generator- including 110 volts AC.

Also capable of protecting Fax machines or any other essential equipment.

Vent

If a current passes through a cell, gases can be evolved. The internal pressure could rupture the cell if it is sealed. Most dry cells are fitted with a vent to relieve this pressure. The vent automatically reseals.

This is why Sealed Lead acid batteries should be charged upright.

Voltage

The voltage of batteries is quoted as ‘nominal’ because it varies during the life of the battery and the amount of current being taken from the battery. If the voltage of a new battery is measured (across a large resistance) it may be a little higher. This will soon drop to the nominal voltage and later in life the voltage will drop further - the torch becomes less bright as the battery gets used up.

The voltage of Alkaline batteries droops in a curve during its life.

Lead-Acid, Zinc-Air, Silver-Oxide and NiCd batteries have a much more constant voltage - a ‘flat’ discharge/time curve.

Watch Batteries

Although various chemistries have been used, most batteries are Silver-Oxide with Alkaline as a cheap alternative.

If you don’t have the original battery code you can safely go on the size of battery.

Provided you can open the watch with a suitable tiny screwdriver or knife (the choice of tool depends on the watch not the user) changing the battery is easy.

Zinc-Air

1.  A battery with Zinc as one electrode and Air as the other, which saves carrying one electrode around as air can be collected, as it’s needed. These cells have a high capacity for their volume and have replaced silver and mercury cells for use in hearing aids. They have been described as “super long life” hearing aid cells.

As supplied, with an adhesive tab, they have a long shelf life. As soon as the tab is removed air is allowed into the cell and the cell begins to self-discharge. Its life will then be about four months whether it is used to not; putting the tab back is not very effective. Zinc-Air cells offer very good value for money because of the quantities used in hearing aids.

Voltage 1.4 volts.

There is a possibility of these cells not working in very dry atmospheres; I have not heard this reported in Europe.

2. Development work has been done on Zinc-Air fuel cells to power electric vehicles.