Specifications

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If we were to use a lead acid battery in our final design, there would be a few specific
requirements that we would need to follow. First, the area where the battery was
located would need to be well ventilated, as the hydrogen gas produced while charging
the battery is explosive. Next, we would need to look at the specific charge program for
the battery that we choose, as it could be different between the flooded, gel, and AGM
batteries that we have looked at. We would then need to make sure that the battery is
constantly charged after each use as to prevent the voltage from dropping below its
threshold. Finally, the temperature of the battery would need to be constantly
monitored, and charge to the battery would need to be cut off if the battery was frozen
or if the ambient temperature of the battery exceeded 120° F (49° C).
Figure 8 – Nickel-Metal Hydride Battery Charger Circuit
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An example of a nickel-metal hydride battery charger is shown above. Nickel-metal
hydride batteries have different charging methods than that of lead acid batteries. It
should first be noted that most of the nickel-metal hydride batteries tend to charge much
quicker, as the charge time at a 1C charge rate is generally around only one hour long.
The difficulty of charging a nickel-metal hydride battery comes with that fact that it is
more difficult to monitor when the battery has reached its full-charge state. Generally,
most nickel-metal hydride chargers use a combination of methods to monitor the
battery‟s charge. Below is an illustration of the charging characteristics of a nickel-based
battery.