Thomas has an Android mobile phone and it charges really slowly. Rich says that with Android phones, the charging devices are hit and miss and using a fast charge device may not be the best option. Or, it could be a cheap cable that's slowing it down. Try changing out the cable first. The he should investigate the battery. If it has a removable battery, he could try replacing it and see if it speeds up charging. If so, he'll know it's a faulty battery.