Specifications

2.11.6 Zinc Nickel Battery

While zinc nickel batteries have been used in various forms for years, this

technology’s entry into the consumer market is recent. Compared to traditional

nickel metal hydride and nickel cadmium rechargeable cells, these offers several

advantages. First, the number of useable recharge cycles is greatly increased

over the other technologies. In addition, in offers a higher capacity (in mAh) than

the other batteries, all while continuing its most significant advantage – it offers

1.6V in a single cell compared to other rechargeable AA cells that only offer 1.2-

1.3V. It also offers this performance more consistently over its lifetime.

However, this technology is not without its disadvantages. The largest

disadvantage is that it is widely available only in AA format, which, as mentioned

in the alkaline section for AAs, is not a desired configuration for batteries in the

portable unit. In addition, to achieve the aforementioned number of charge

cycles, special charging procedures are required. As such, it becomes unfeasible

to use for an application where charging cannot be assumed to be done in a

constant and predictable manner.

2.11.7 Battery Comparison

While all the batteries selected have their own disadvantages and advantages,

only a single battery type will be selected for the portable unit. A final selection

was made with respect to the requirements set out at the beginning of the

research. Eventually, a decision had to be made about which advantages

outweighed disadvantages enough to provide an optimum battery for the unit.

While nickel metal hydride initially seemed like an optimal solution, the significant

size and weight penalty made it an unattractive option.

In the end, the lithium ion battery provided the best balance of life, safety,

capacity, and flexible recharging ability, as well as size and cost concerns. While

lithium ion has significant safety considerations, the prevalence of lithium ion

batteries in many consumer devices today prove they can be used safely if used

with the appropriate protection circuitry. As such, its advantage with size cannot

be ignored. The results of the comparison are summarized in Table 2.11.7-1.