Specifications

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2.13 Batteries
Batteries are going to be used to store capacitive charge in the secondary
microcontroller for the HVAC control system. The two kinds of batteries that exist
today are primary batteries and secondary batteries. For our project we will most
likely use the secondary batteries which are also known as rechargeable
batteries. This is good because once the microcontroller runs out of battery life it
can be recharged up as many times as we want. We can figure out how much
discharge time that the battery will have for the secondary microcontroller
according to the relationship of t=Q/I, where I = current for the battery (in
Amperes), Q = charge given out by the rechargeable battery (in Coulombs), and t
= change in time (given in seconds).
Subcategories of rechargeable batteries:
1) Lead-Acid
2) Nickel-Cadmium
3) Nickel-Zinc
4) Nickel Metal Hydride
5) Lithium-Ion
6) Alkaline
Lead-acid batteries were the first rechargeable battery ever created. Some
positive advantages of lead-acid batteries are that they are relatively low cost,
very reliable, and have low internal impedance. They are also robust, tolerant to
overcharging, and can deliver very high currents. The limitations of these
batteries are there is a possible danger of them overheating during charging
period as well as being very heavy and bulky in weight.
Nickel cadmium batteries have various applications that include emergency
lighting, remote-controlled model airplanes and boats, wireless communications,
and mobile computing. Despite their low resistance that can generate high
currents. These batteries typically send out a voltage of 1.2 V. Nickel cadmium
batteries have low internal resistance, tolerable discharge rate, and have a
nominal cycle life of over 1,000 cycles. Many other features of the nickel
cadmium batteries include its susceptibility to memory effect, being prone to
damage by overcharging, as well as having an energy density double the amount
of lead acid batteries. The batteries are reasonably priced and supply a wide
temperature range to achieve adequate performance. Another concern with
Nickel cadmium batteries is that the chemical composition of the battery is
composed of the element cadmium which is a very lethal heavy metal.
Nickel metal hydride batteries are the powering force to start electric cars as well
as other consumer electronics. Nickel-metal hydride batteries have a higher
capacity and don‟t suffer from memory effect when compared to nickel-cadmium
batteries. One disadvantage for nickel metal hydride batteries is that they have a
fast rate of discharge when the batteries are not used for a long period of time.