to choose the right size of battery
As mentioned earlier, batteries come in all shapes and
size, from types no larger than a shirt button, to a
battery system filling an entire room.
To find the size of battery you require you generally
need two pieces of information, battery load and back-up
times. (Note: other factors may also have an effect).
Whether you power lights, motors, electronic equipment
or a toy vehicle you equipment will draw a load in AMPS.
If this is unknown then the equipment will have a rating
expressed in Watts which may simply be converted to
Amps by dividing the value by the normal voltage of
This is the time you require the battery to support
the load described above and is often called Autonomy
or discharge time.
Example: To power a cordless electric tool for a total
of 3.0 hours before recharging. With these two pieces
of information use our selection graph to plot an intersection
point from which you will determine a required size
or capacity in Amp. hours (Ah).
Our figure has been rationalized into rounded figures
of capacity. If your intersection point falls between
two lines choose the next highest value.
Always choose a suitable sized battery from the ranges
appropriate to your application.
You may notice that the chosen capacity in Amp hours
is often higher than the Value of Amps x Hours used,
in our example using 10AMPS x 3 HRS = 30Ah and the chosen
option being 38 Ah. This is because the capacity ö¿cAöÑ
of each NP battery is stated at the 20 hour discharge
rate. You will only get full capacity if discharged
over that length of time.