Hi Widge. In answer to your question my charger gets fairly warn too. I own 3 eBikes and they all tend to get warm, although it shouldn't get so hot that you can't hold it. Although charging overnight probably isn't going to be a disaster I have a healthy respect for lithium batteries - if by some chance they ignite all hell breaks loose and it could easily burn down your house so I make it a rule never to charge a bike whem I'm not around to keep an eye on it....just on the off chance that something goes wrong. Lithium battery chemistry is pretty well known and it's basically the same for any good lithium battery, so if you want to extend the life of the battery as long as possible you should never charge it above 80-90%, try to keep it from going below 20% and if possible never go to 0 - that is extremely hard on the cells and will degrade the battery pretty quickly. If you're not going to use the bike for a while you should try to leave it with about a 50% charge, never let it stay empty for long and don't leave it at 100% for any length of time. Although that applies to any eBike battery it's more of a pain if the Gain battery goes bad since it's not easily user replaceable. I don't really know where you're located but I'm in South West Florida where it is unbelieveably hot - when I rode today it was 100F with about 90% humidity, so at home I make sure to keep the bike inside my house where it doesn't get too hot. Not a problem here, but the same applies to leaving it in a place where it's really cold. Youngoldbloke, thanks for the tape tip. I saw where the plugs have a mark but it's black on black - Basque eyes must be incredibly good I can never see them and it's a pain to plug in. Your tip of marking it with tape is going to save me a lot of time and cussing.