How to Choose Batteries(Battery type)?

• The Nickel Cadmium (NiCd) battery.
• The Nickel-Metal Hydride (NiMH) battery.
• The Lead Acid battery.
• The Lithium Ion battery.
• The Lithium Polymer battery

What’s the Best Battery?

 compares the characteristics of the six most commonly used rechargeable battery systems in terms of energy density, cycle life, exercise requirements and cost. The figures are based on average ratings of commercially available batteries at the time of publication.

1. Internal resistance of a battery pack varies with cell rating, type of protection circuit and number of cells. Protection circuit of Li‑ion and Li-polymer adds about 100mΩ.
2. Cycle life is based on battery receiving regular maintenance. Failing to apply periodic full discharge cycles may reduce the cycle life by a factor of three.
3. Cycle life is based on the depth of discharge. Shallow discharges provide more cycles than deep discharges.
4. The discharge is highest immediately after charge, then tapers off. The NiCd capacity decreases 10% in the first 24h, then declines to about 10% every 30 days thereafter. Self-discharge increases with higher temperature.
5. Internal protection circuits typically consume 3% of the stored energy per month.
6. 1.25V is the open cell voltage. 1.2V is the commonly used value. There is no difference between the cells; it is simply a method of rating.
7. Capable of high current pulses.
8. Applies to discharge only; charge temperature range is more confined.
9. Maintenance may be in the form of ‘equalizing’ or ‘topping’ charge.
10. Cost of battery for commercially available portable devices.
11. Derived from the battery price divided by cycle life. Does not include the cost of electricity and chargers.

Observation: It is interesting to note that NiCd has the shortest charge time, delivers the highest load current and offers the lowest overall cost-per-cycle, but has the most demanding maintenance requirements.

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