When is a 7Ah battery not a 7Ah battery?
Temperature effects Capacity:
Many battery manufacturers rate their batteries at 20°C.
Below 20°C, the battery can have a significantly lower available capacity.
Over 20°C, the battery can have a significantly higher available capacity.
This can easily be as much as ±50% of the rated capacity.
Bear in mind differences in temperature when testing - for example in an enclosure or next to a
hot transformer (higher than rated reading), or located externally / cold environment (lower
than rated reading).
State of Charge effects Capacity:
Most battery manufacturers rate their batteries at rest.
Charging Voltages and Currents have a direct impact on available capacity.
Bear in mind when testing batteries recently removed from charge.
Many new batteries are not fully charged when produced.
Some Cyclic batteries do not obtain full capacity until cycled several times.