Well, due to some incident, my PSP has to charge it's battery externally through an external charger. I've been doing this for about 2 and a half years now I think.

Well, one day (today as of posting this) I decided to charge the battery and I was stupid to leave it next to a sunny window on a hot day.
When I came back the charger the light on the charger was flashing and the battery and the charger were very hot.
My so I let them cool down for about a minute and tried to connect them again. It charged normal until later, the light started flashing again.
When I put the battery in my PSP it worked fine so I guess the problem was the charger.

I'm going to let them cool down and try again later, this wasn't the first time I left my charger and battery next to a sunny window but it is however the first time my charger acted like this.