Battery Information.

Battery Care and Feeding.

Common rechargeable batteries are generally one of four types. These are lithium ion, nickel metal hydride, nickel cadmium, or sealed lead acid. Within each type there are subtypes. For example, nickel cadium batteries (NiCads) exist in sintered cell and pocket cell types. Sealed lead Acid batteries exist in gell cell and absorbent glass mat. These different types of batteries have different characteristics which gives them more or less suitability for a given application.

One of these characteristics is most closely associated with the NiCads. This is known as the "memory effect". A NiCad cell will "remember" how full it is charged and how deeply it is discharged and will not want to go past those points without a large drop in voltage. This makes it seem like the battery will not hold a charge in some applications. To get around this, some battery and appliance manufacturers recommend completely discharging and then fully recharging a NiCad battery so it "remembers" a full cycle.

Sealed Lead Acid batteries should not be run all the way down because it can cause the plates to sulfate and quickly kill the battery. These should generally be kept fully charged and be charged at the earliest opportunity after discharging them. Be careful not to overcharge sealed batteries, as the seal will burst and the liquid will evaporate ruining the battery in a short time.

Each type of battery has slightly different voltage characteristics.


The type of battery used for providing power in RE applications is known as a "deep cycle" battery. True deep cycle batteries have heavy duty plates and generally weigh over one hundred pounds for twelve volts worth of cells. These come in all the same flavors as the home flashlight batteries, but because of their weight they are not very portable. They are also designed to store a lot of energy to provide for extended periods of discharge. A regular lead acid car battery is designed for very "shallow" discharge cycles in which the user drains less than twenty percent of the battery's energy before driving the car and recharging the battery. Draining over fifty percent of the energy out of one of these starting batteries will cause permanent irreversible damage to the plates.

Deep cycle batteries are designed for discharging hundreds or thousands of times to the fifty percent level. Below the fifty percent level, voltage starts dropping a lot and "sulfation" can start to decrease the battery capacity of lead acid batteries. Equalization charges are often done with lead acid batteries to equalize the voltages and acid levels in the cells. In an equalization charge, the battery is filled to overflowing by continuing to charge it even after it is topped off. This causes bubbling from the hydrogen gas being produced, so ventilation is required to prevent an explosive condition from arising.

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