I travel between Cape Town and Johannesburg quite often and have found that in Jhb when I charge my phone overnight it lasts much longer the next day. But when charging the same phone in CT overnight - it does not seem to last the next day. Is there an explanation for this, because I really believe that the power might be weaker in CT, but I'm still using the same charger, therefore is the output power from the charger the same even though there might be a different input between CT & Jhb ???