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Popular batteries 2711-4.jpg D, C, AA, AAA & PP3


historic name for a rechargeable battery. More or less always refers to lead acid.
A battery means a quantity of cells used together. These may be housed in one container, such as with 6v and 9v consumer batteries, or they may be separate containers only electrically connected, as is common with large lead acid installations.
Total output ability measured in amphours, current x time.
a single electrochemical unit producing electricity, usually from 1.2v to 3v (commonly 1.5v).
C/20 etc
charge rate. C/20 means capacity divided by 20, C/10 means capacity divided by 10 etc. Eg C/10 charge rate for a 1Ah battery would be 100mA.
one charge & discharge
Deep cycle or deep discharge battery
lead acid battery optimised for deep discharge applications
taking power from the cell
Dry cell
Historic term for zinc carbon cells. Today there are also other dry types, so usage of the term sometimes refers to these as well.
the liquid, gel or paste in the cell
Energy density
amount of energy stored per weight
Float charge
low current charge to keep battery topped up. See trickle charge
Gel cell
Non-flooded lead acid, aka SLA
Emission of liquid content from the cell. Zinc carbon and zinc chloride are prone to this. Leaked electrolyte is corrosive.
Leisure battery
Deep cycle lead acid
Current drawn from the battery
Primary cell
non-rechargeable cell
Secondary cell
rechargeable cell
Sealed lead acid. (SLAs aren't completely sealed in reality.) There are several types of SLA
Starting battery
lead acid battery optimised for engine starting, eg car battery
Trickle charge
very slow (low current) charge. See float charge
a type of SLA lead acid battery

Battery chemistries

Zinc carbon
lowest cost, 1.5v per cell, very prone to leaking
Zinc chloride
slightly improved performance version of zinc carbon
Much greater capacity than zinc carbon. However high drain apps dramatically reduce the capacity they can deliver.
Not prone to leakage
Longer shelf life than ZnC
Ideal for low drain apps, where they give much longer service life than ZnC, and seldom leak.
long service life of upto 10 years if drain very low. Capacity and price are much higher than alkalines. 3v per cell.
Lead acid
Rechargeable, used for heavy high capacity batteries.
Sealed lead acid (SLA)
Spillproof lead acids.
NiCd (nickel cadmium)
Popular rechargeables, small light low capacity
NiMH (nickel metal hydride)
As nicad, but higher capacity & cost, and require NiMH chargers
Silver oxide
Coin cells, 1.4v per cell
Li-ion (lithium ion)
Most expensive type of rechargeable with high energy density. Used in laptops and a few cordless tools.

Coin cells


Widely used in PCs, watches, and miniature battery appliances. The smaller ones are also known as button cells.

With tiny capacity and max load current, these cells are only suited to micropower uses.


3 types of chemistry are popular in coin cells:

  • alkaline - 1.5v per cell, lowest cost
  • silver oxide - 1.4v per cell
  • lithium - 3v per cell, highest cost

Common sizes

There are a large number of sizes still in production. A small range are much more popular than the rest, and are listed here. If you don't know what battery is needed, these are the first to look at.

Nearly all these battery sizes have various other names as well.

Most popular

Popular batteries 2711-4.jpg
  • AAA 1.5v
  • AA 1.5v aka penlight
  • C 1.5v
  • D 1.5v (appeared in 1896 for flashlights)
  • PP3 9v
  • PJ6 6v - spring top lantern battery

1960s & 70s appliances

  • PP9 9v
  • other PP sizes are occasionally seen, eg PP6, PP7, PP10, PP11
  • ? - 3v one somewhat like 2x C cells end to end
  • MN1203, 3R12, 3396 4.5v, strip terminals, mainly for torches (pictured)

Cordless tools

sub-C Nicad 1.3Ah - 2Ah



CR2032 20mmx3.2mm (3v lithium) is the most common BIOS battery in desktops. These retain BIOS settings when mains is unplugged.

  • CR2025 20mm x 2.5mm less often used
  • CR2016 20mm x 1.6mm most popular in laptops


12v 30-60Ah lead acid battery, either round or flat posts.


  • AA 1.5v
  • 123 3v
  • CR2 3v

Burglar alarms, UPSes

Sealed lead acid, 6v or 12v, various capacities


  • AAA 1.5v
  • AA 1.5v
  • PP3 9v
  • N 1.5v info

Battery capacity

These are typical figures only, in real life capacity varies according to brand and use conditions. Ref

          alkaline   nicad/NiMH
N    1.5v  1Ah
AAA  1.5v  1.2Ah     0.3 - 1 Ah
AA   1.5v  2.8Ah     0.7 - 3 Ah
C    1.5v  8Ah       2 Ah
D    1.5v  12Ah
PJ6   6v   14Ah
PP3   9v   0.6Ah     0.2Ah

Note that although alkaline cells have higher Ah ratings than nicads, they provide rather less capacity in high drain apps, and NiMH can give more time of use in these apps. capacity Ref

Batteryshowdown tested many brands of AA cell, with the following results:

  • ZnC about 0.6Ah
  • Alkaline about 2.1Ah
  • Lithium 3-3.5Ah
  • All brands of alkaline battery tested showed similar capacity

Manufacturers' data:

Best before dates

best before 1940

Best before dates are manufacturer recommendations intended to ensure batteries reliably do their job. Just like food best before dates, many are still fine long after this date, but not all.

In 2008 a bag of batteries was found containing a zinc chloride 9v stamped BB 1993 - and surprisingly it was good as new. 3/4 of the 1999 ones were also usable, a couple had corroded through.


All the popular battery chemistries are prone to leaking corrosive chemicals on occasion, but one type does it far more often than the rest: zinc chloride.

  • Zinc chloride leaks as a normal end of life event - a good reason to avoid them
  • Alkaline leak occasionally, but not often
  • NiCd & NiMH very occasionally leak
  • Wet lead acid tend to spray tiny amounts of acid mist out the top
    • wires and connectors should be greased with petroleum jelly
    • other metalwork such as holders & clamps should be well painted


See Also