In off-the-grid systems microhydro
systems batteries are an essential component used to store the energy
generated by the water turbine so it
can be reused later as needed. Batteries can also be used as
part of a grid-connected microhydro system to provide battery backup in the event
the grid goes down for a period of time.
The batteries typically used in microhydro electric systems are 6-volt,
deep-cycle, lead acid batteries. These are different than the
type of battery you use in your car. A car battery is designed
to provide a strong jolt of amps to get your car started but after
that the discharge tends to fall off rapidly. A deep-cycle
battery provides less of a jolt but is instead designed to produce a
steady discharge of electricity over a long period of time.
A popular type of battery specifically designed for home energy
systems is the Surrette battery. They are large deep-cycle
batteries with a larger form factor than a car battery and are
designed to be used as part of a battery bank.
Consider carefully before choosing to use battery systems for
electrical storage. If you have access to the grid the grid
itself can serve as your energy storage and you receive energy credits
for every kilowatt hour you put back on to the grid. Batteries
require maintenance and can be fussy. If you have no grid access then
batteries may be the only option you have. If so, spend time to
think through your approach to maintaining the battery bank and
keeping the flow of electricity out of it stable.
Lead acid batteries operate best at around 70 degrees Fahrenheit or
21 Celsius. At higher or lower temperatures their performance
declines, sometimes dramatically. Therefore consideration should be
given to storing batteries in areas that are at the appropriate
temperature and which are well ventilated. Batteries also tend
to lose water when they are charged and so need to be refilled
periodically. In general, it is a good idea to check your batter
bank every month in order to be sure that the lead plates don't run
out of water. It is best to use distilled water when refilling
batteries in order to avoid residue buildup and to avoid compromising
Given the need to regularly fill and maintain batteries, make sure
that they are located in a place that is easily accessible.
Avoid putting the batteries on to high a shelf which can make filling
them awkward. One useful gadget you might wish to consider are
hydrocaps. These are replacement caps for your batteries that
contain a catalyst which reacts with the hydrogen and oxygen released
by the battery in order to produce water. They can cut the loss
of battery water by as much as 90%. There are also commercial
batter filling systems which can be purchased which can refill
multiple batteries from a central reservoir.