The lifespan of a battery is best defined in terms of “charge cycles”. Where Li-ion batteries are allowed to drain to 0% from a top charge of 100% (as is commonplace for mobile phones), they will exhibit a decay in power storage after only 500 charge cycles (say 18 months, as maybe your experience for mobile phones) – but they are still storing power just less of it as time goes by. However, less well known is that if you limit the extremes of the charge state of Li-ion batteries, their lifespan (the number of charge cycles before they exhibit storage loss) increases exponentially. As such, the QIKPAC is pre-programmed to shut down at 10% and charge only to 90%. This minimal limitation (to 200Wh) extends the lifespan of the battery more than fivefold – beyond 5 years (with 70-80% of the initial capacity remaining) and potentially to 10 years before a noticeable degradation of storage capacity.