Bicycle Lighting

Bicycle Lighting - Batteries - Alkaline

Front Driving Lights	Resource Page	Rear/Front LED Lights
Generators	Links & Reviews	Batteries
Zinc Carbon	Alkaline	Zinc Chloride
Sealed Lead Acid	Nickel Cadmium	Ni Metal Hydride
Lithium Ion	Lithium	Lithium Polymer

Alkalines (eg Duracell, or Ever Ready Energiser) are the most familiar primary cells. They have excellent energy density (ED), bettered only by very expensive Lithium cells - but this is dependent on their being hooked to a relatively small current load. A pair of 'D' cells can run a 2W bulb reasonably well, but smaller cells or a higher-wattage bulb result in rapidly-deteriorating and yellowing light.
'New Formula' Alkalines. Most manufacturers now offer new formulation Alkalines, often with some mention of Graphite on the packaging, which claim improved performance over 'standard' types - at an increased price. Eg, Duracell Ultra, Philips Powerlife, etc. Some of these are good, some not - Alkaline battery performance is much more variable than it used to be, and there's a compritive test of some types at Battery Test
Alkalines are really unsuitable for high power lighting applications, with current drains of 1 Amp or more they do not perform well, giving a poor quality of light and a very much shortened run time. This table is derived from Duracell's own data sheet, and illustrates this point, showing run time to 0.8V, and total capacity, at different current drains. (Note - 0.8V is too low for lighting purposes - for practical runtimes you can halve the values shown below.)
```
     drain runtime capacity
     mA      hr     mAh
     +----+-------+------+
     20     830    16600
     50     330    16500   (led light)
     100    160    16000
     200     77    15400
     500     20    10000   (utility 2-cell light)
     1000     7.5   7500   (6V 6W light)
     2000     2.3   4600
     5000     0.1    500
     +----+-------+------+ 
```
One way of using Alkalines effectively in conjunction with high-power bulbs is to run them in conjunction with Willie Hunt's Lighting Voltage Regulator. See Three contrasting approaches to bright lighting

Running a lower powered light, something like a 3v 2w bulb, Alkalines offer a very good weight-effective solution to the problem of keeping a light going all night.
While prices vary dramatically for different brands and outlets, there seems to be no correlation between performance and price. See Battery Test.
Value For Money (VFM) and Power For Money (PFM) figures below assume middle-of-the-road UK prices, and the Alkaline batteries quoted below are 'standard' Duracell or Energizer types. Some other newer types give better performance than this, see Battery Test.
D cells are much more cost-effective than the smaller packages, C cell or AA cell. However D cells are quite heavy, 280g for a 3 volt pair, and may offer far more capacity (around 12 hours run time) than is required. In this case a more weight-effective solution may be Alkaline C cells or Zinc Chloride D cells.

Here is a table of possible 4A-h configurations, to drive a 3V 2W bulb for about 6 hours.
For the best performance, power-to-weight, see the ED figures. For the best value, look at the VFM. For performance at a good price, check out the PFM column.

      type            weight(g) V A-h runtime  ED  price  VFM  PFM
     +------------------+-------------------+----+------+--------+
     ZnC     (4 D-cells) 400    3  5    7.5   3.8   4.0   3.8  1.9
     ZnCl    (2 D-cells) 200    3  3.8  5.7   5.7   2.4   4.8  4.8
     Alkaline(2 D-cells) 280    3  8   12.0   8.6   2.9   8.3  5.9
     Alkaline(2 C-cells) 138    3  3.4  5.1   7.4   2.7   3.8  5.5
     Alkaline(6 AA-cells)132    3  4    6.0   9.1   4.3   2.8  4.2
     Lithium Sulph(4xAA)  60    3  3.4  5.1  17.0  10.0   1.0  3.4
     Alkaline(2xD rechargd)280  3  6.5  9.7   7.0   2.9   9.1  6.5
     +------------------+-------------------+---+-------+--------+

Most people would use Alkalines in a typical 2-cell front light to run something like a 2w 3v halogen bulb. Note that to run such a bulb all night would require a pair of Alkaline D cells - a lamp using C cells will only last about 5 hours and one of the modern 4xAA cell lights will only last about 4 hours. AA cells are a relatively expensive way to buy energy.

Alkaline primary cells can be recharged. This is strongly discouraged in most countries and especially by the battery manufacturers - well, they would, wouldn't they? A special (but inexpensive) charging circuit is required, or chargers are commercially available (in the UK, from Maplin or Innovations, about 30UKP). Some elementary precautions should be taken, but they can be restored close to full voltage a few times before they get tired. This improves VFM and PFM a little, in non-critical applications.

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Generators Links & Reviews Batteries

Zinc Carbon Alkaline Zinc Chloride

Sealed Lead Acid Nickel Cadmium Ni Metal Hydride

Lithium Ion Lithium Lithium Polymer