Universal external battery Earldom ET-PB41 has a capacity of 10000 mAh. Please note that in order to get the number of charges for which a fully charged power bank is enough , the specified number cannot be simply taken and divided by the battery capacity of the device. The fact is that the capacity value is indicated by the manufacturer of the power bank at a voltage of 3.7 V. While a portable battery is used for a phone or tablet, which, as you know, operate from a voltage of 5 V. Therefore, to calculate how many uses the charge will last power bank, it is necessary to take into account the voltage transformation ratio and do not forget that part of the charge will be spent on the transfer of electrical energy, incl. take into account the generated heat energy (the power bank and the charging cable will heat up).