Specifications

long period of time and a larger storage capacity than an SLI battery of similar size.

Deep cycle batteries are popular in boats and RV‟s, as these have more electronic

accessories to run, often without the engine running, than a car typically does. These

are also the typical battery of choice for storing the energy produced by solar panels

and wind turbines, just like our device will need. Unlike the cranking battery, deep cycle

batteries are designed to have a significant amount of their charge depleted before they

are re-charged. The lead plates are less porous and thicker than those of SLI batteries,

which is the reason that the current they provide is less. These thick lead plates are also

the reason deep cycle batteries can withstand repeated deep cycling. The lead doesn‟t

dissolve and leave gaps that cannot conduct a charge as quickly as the thin lead plates

in SLI batteries do. Deep cycle batteries typically weigh between 15 and 70 pounds, and

their cost is usually between $50 and $300, though there are many exceptions to these

generalities. These batteries, in configurations that will work for this application, are

readily available at many local stores and on the internet, so replacements are easily

attainable.

There are two main types of deep cycle lead acid batteries, known as flooded and valve

regulated lead acid (VRLA) batteries. Flooded batteries are typically longer lasting, and

cheaper than VRLA batteries. Overcharging is not a big problem with them, as the water

lost (due to electrolysis) can be replaced via removable caps on the top of the battery or

in some cases the battery is designed with extra electrolyte already enclosed if it

doesn‟t have caps. Caps can be seen as an advantage as the battery can be refilled as

many times as necessary, but it also means water can evaporate from the battery thus

requiring periodic maintenance. One of the downsides of all flooded batteries is that

they are less durable. They are sensitive to movement and vibrations because the lead

supports itself in the electrolyte and they must also be used in an upright position so

that the lead plates will be properly submerged in the liquid electrolyte. Another

disadvantage of flooded batteries when compared to VRLA batteries is that the

electrolyte can be spilled. For this reason, most national and international shipping

companies will not ship them. The diagram below shows the typical construction of a

flooded lead acid battery.