Battery selection

1. S.Gomathy M.E.,M.B.AS.Gomathy M.E.,M.B.A
Battery Selection
S.Gomathy M.E.,M.B.A
Assistant Professor
Department of EEE
Kongu Engineering College

2. S.Gomathy M.E.,M.B.A
How to Select a Battery?
 The selection of a battery is done by seeing the battery
parameters.
 The parameter values for voltage rating, current rating,
capacity rating, number of charging-discharging cycles and
shelf life differs from battery-to-battery.
 These values also differ from one manufacturer to another
 While designing a solar PV system comprises batteries, the
one problem often faced is a proper choice of battery from
many available batteries.

3. S.Gomathy M.E.,M.B.A
Types of Battery
 Based on application, the type of a battery is chosen.
 For example, primary batteries are used in portable devices which
run on very low current, such as electronic watch, torch and radio.
 Primary batteries are used for one time only.
 They are cheap and easily disposable.
 Some applications require high current to run devices.
 In such cases, the secondary batteries or rechargeable batteries are
used which provide high current as they have high capacity and can
be recharged a number of times.
 The rechargeable batteries are costly compared to other primary
batteries, but they are cost effective over long time use.

4. S.Gomathy M.E.,M.B.A
Voltage and Current
 A battery should be selected according to the voltage and current
requirements of the instrument to which it is connected
Temperature Requirement
 The batteries are designed to operate at certain temperature, normally about
25 °C.
 In practice, the prevailing temperature or ambient temperature may be
different.
 Sometimes, the ambient temperature can be above 45 °C and sometimes, it
can be negative or at freezing temperature.
 The battery output current and its capacity depends on the temperature.
 At higher temperature, batteries can deliver higher current as compared to
lower temperature.

5. S.Gomathy M.E.,M.B.A
 At lower temperatures, like below 20 °C, the chemical reactions in
battery become slower and the battery can only deliver lower current
than designed value.
 At higher temperatures, the battery may provide higher current but
its life decreases when operating temperatures are high.
 At very high temperature, some batteries can be dangerous causing
explosion and fire can occur.
 Therefore, depending on the operating temperature of battery,
appropriate battery must be chosen for a given applications.
 The manufacturer datasheet provides the information about safe
operating temperature and how the capacity and current will change
with temperature for a given battery.

6. S.Gomathy M.E.,M.B.A
Shelf Life
 Batteries shelf life is directly affected by the rate of self-
discharge.
 Self discharge occurs all the time, even when the battery
is not used.
 Some batteries have extremely low self-discharge rates,
such as most of the lithium battery whereas, some nickel
metal hydride batteries can lose up to 4% of their capacity
every day.

7. S.Gomathy M.E.,M.B.A
Charge-Discharge Cycle
(If Rechargeable)
 The number of charge-discharge cycle of battery depends on the
type of battery.
 Normally, for rechargeable applications, battery with large number
of charge-discharge cycle should be chosen.
 For instance, for standalone solar PV systems, batteries with large
number of charge-discharge cycles are chosen.

8. S.Gomathy M.E.,M.B.A
Cost
 Costing is based on the type of batteries selected and it’s pricing by
different manufacturers.
 Also, it depends on the features of the battery.
 Generally, the maintenance free and advanced technology batteries
are expensive.
 In some cases, it may require that system must perform in all
conditions, therefore, the over sizing of the battery is done.
 In such cases, the cost of the battery is not important but the reliable
system performance is given importance.

9. S.Gomathy M.E.,M.B.A
Availability
 Before selecting a battery, we should check its availability in the
market.
 If a battery, rarely available, is used in a system, it may create
problems while replacing or buying new one for the system.
 So, a battery that is readily available, easy in transportation and can
be bought even in remote places, should be selected

10. S.Gomathy M.E.,M.B.A
Thank You