Devices with lithium batteries are always stored with 50-60% charge. This maximises the life of the
battery when the device is not in use.
You should charge the device fully now. This action will not only maximise its initial capacity but it will also balance the individual cells that make up the
battery. In effect the process optimises the
battery pack and makes it ready to use.
In the future if you plan not to use the device for an extended period do the same as the manufacturer. Discharge the device to around 60% and when you wish to use it again charge it fully first.