Primary batteries cannot be recharged and are constructed of alkaline, zinc air, or
zinc carbon materials

Secondary batteries are rechargeable and are constructed of lead acid, nickel
cadmium, nickel metal hydride, lithium and lithium-ion. New chemistry’s are being
developed everyday. Lead acid batteries have been used in cars and trucks for
almost 100 years. They are designed to start a vehicle, giving a large current
flow for 20 seconds or so, then accept a charge from the, then accept a charge
from the alternator to recharge the battery. A deep cycle lead acid battery is designed
to produce a lower current draw for a long period of time, then be recharged at a lower
current for a longer period of time. These batteries are used in golf carts and fishing boats.
They have thicker plates and a dense oxide paste. A 12 volt lead acid battery should
never be discharged below 10.5 volts and under no circumstances should a lead acid
battery be left in a discharged state. This will cause the plates to sulfate and kill the battery.

Sealed lead acid batteries are also called valve regulated batteries. They are sealed so
that the electrolyte will not leak when the battery is turned up side down but have
valves that open to release gases if the battery is overcharged or misused in some fashion.
Once the valves have been opened, the life of the battery is effected.

Gell cell batteries are much like sealed lead acid. They are sealed and have valves
but the electrolyte is a gell rather than a liquid. Gelled batteries usually do not have as
high an amperage rating as the same sized sealed lead acid battery.

Nickel cadmium technology is older and known for its "memory effect". True memory effect
rarely occurs in consumer devices because it requires many cycles to precisely the same
states of charge and discharge. Most failures in consumer devices occur because
of overcharging and or heat. Don't completely discharge packs every time to avoid
memory effect. Discharging a pack too far can cause the stronger cell(s) to charge the
weakest cell in the opposite direction. This is called reverse charging and will lead to a very
early death of the pack. However, through normal use, it's fine to occasionally run the devise
to the point where it indicates a low battery. NiCad's that are weak due to overcharging
can sometimes be rejuvenated by a full charge/deep discharge cycle. Unfortunately,
the only way to assure that reverse charging doesn't occur is to discharge each cell
separately. With proper operating procedures and maintenance, and average NiCad
battery will last between 1000 to 1300 cycles.

Nickel-metal hydride batteries have approximately 30 to 80% more capacity than NiCad
and no memory effect. NiMH batteries perform better on low discharge rates than NiCad and
are preferred in small portable devices because they give longer run times. They also take
less time to recharge. Follow your manufacturers instructions on charging. To prolong the
life of the battery pack, remove it from the devise and charger when not in use and store
it in a dry, cool place. Do not run the battery completely dead or discharged. Fully
charged batteries discharge rapidly even when not in use. Recharge prior to use.

Lithium and Lithium-Ion batteries are expensive compared to NiCad and NiMH but worth
the money if you need their performance. These batteries have higher output but lower
weight. If exposed to extreme cold (below 50 F), the effective operational time decreases
significantly. Exposure to temperatures below 32 F will render the battery inoperative.
Charge the battery pack at least once every six months. Do not leave the battery pack
being charged for long periods of time. Be careful to never puncture these batteries
as they might explode if air gets inside.