cheap chargers will definitely do that. prime example why I don't trust charging a battery inside the vehicle, shame on the engineers for encouraging it
I've had problems with Duratrax chargers... ick. True story... ordered an intellipeak and plugged it in, charger starts vibrating across the table. They wouldn't warranty it... stupid TLP chargers... yeah, Intellipeaks are manufactured by TLP. I've also had a few planes crash due to false full charges. I don't trust their chargers for anything... same with the Onyx line. My stepdad lost a plane to that thing. We've gone through the debate on if it was us or chargers fault, but after pulling out the volt meter and comparing it to what the charger said it put into it... charger went bye bye.