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Electricity > Batteries and Cells

The table below shows the five main types of batteries and cells used in schools and the home. Typically cells are devices made up of two electrodes separated by an electrolyte. Examples of these single cells are AAA, AA, D and C type. The word Battery describes several cells connected together in series. 9V PP3 batteries are actually six 1.5v cells wired in series.

Common coding International standard number Other names
D R20 SP2, HP2, RX20. MN1300, R20, LR20
C R14 SP11, HP11, C11, RX14, MN1400, R14, LR14
AA R6 C7, RX6, MN1500, HP7, R6, LR6
9V 6F22 PP3, PP3C, RX22, MN1604
AAA R03 C16, HP16, MN4200, R03, LR03

There are many types of battery available that include names such as; Alkaline, Zinc Chloride, Ni-Cad etc. Each is made from a combination of different metals and designed to be used for a specific application. Below is a table showing the different types of battery and cell and their intended use.

Type Application Typical voltage Notes
Zinc Chloride Zinc Carbon Torches, lamps, clocks, small toys 1.5V Cheap to replace. Zinc Chloride has mainly superseded Zinc Carbon cells.
Alkaline Manganese Cassette players, torches, cameras 1.5V Good for continuous or intermittent use
Silver oxide Button type- calculators, cameras 1.55V High purchase cost Good for continuous or intermittent use
Zinc Air Button type- hearing aids 1.4V Good for continuous or intermittent use
Lithium Manganese Button type- calculators 3V Good for continuous or intermittent use
Nickel cadmium Rechargeable – heavy duty motor applications 1.2V High cost but can be recharged hundreds of times
Lithium ion Rechargeable- laptop and phone batteries 4V High cost but long life, often made for specific products
Nickel metal hydride Rechargeable- mobile phones, laptop batteries 1.2V Long life between charges, high initial cost.

Batteries and cells have a shelf life. Over time they will discharge themselves if not connected to an appliance. The level of discharge will vary with the type of battery or cell, the table below gives a rough estimation of discharge over time. Many modern batteries will have a 'best before' type date either on the battery itself or on the packaging it came in.

System Self-discharge
Alkaline-manganese round cells max. 2%/year
Zinc round cells max. 4%/year
Rechargeable (dependent on system) 10% to 25%/month

Most schools use standard non-rechargeable batteries in most applications however with modern microscopes and dataloggers, many come with built-in rechargeable devices which need connecting to mains power to recharge. The table below shows the good and bad points of standard and rechargeable batteries and cells.

  Standard batteries/cells Rechargeable
Initial cost
Low High
Discharge time
(per charge)
High Medium
Clocks, smoke alarms,
door chimes
Yes No
Uniform voltage
throughout life
Starts to drop as soon as connected yes

Important safety notes
  • Always fit batteries the correct way around observing the – and + marks on the appliance.
  • Never mix old and new batteries, always replace the entire set in one go.
  • Store batteries away from metal objects that may cause short circuit. Do not put batteries in your pockets. They can come into contact with keys, coins and in one story I have heard, steel wool which can ignite when touched across the terminals of a 9V battery.
  • Remove batteries from appliances that are not in use for a long time as the batteries may corrode.
  • Never dispose of batteries in a fire, they may explode.
  • Never try to recharge standard batteries. They may explode.
  • Button cells pose a serious danger if swallowed. Keep away from small children.