Who really knows what the real capacity of a battery is? Is not an easy question to answer, because manufaturers rate their batteries in a very optimistic way.
What makes difficult to know the real battery capacity is the fact that normally an external battery is used witht multiple devices that draws different amount of current. In fact, it is quite normal, that the same device draws more current in one situation than in other.
We at ZenSlider test each battery individually following this testing procedure:
- We charge each battery with their own charger.
- Once the battery is 100% fully charged, we connect a measuring device called Electronic DC Load to the battery. This lab test equipment is configured to discharge the battery at a fixed current until a minimum thershold voltage is reached. When the battery has been discharged, we know exactly the REAL capacity in amp-hour and also show the graph the discharge curve.
- Finally we individually label each battery with the real capacity measured. That allows us to guaranty that the batteries sell a minimum of 2.5 hour with ZenSlider.