I don´t think that is a good idea. Lithium batteries are quite dangerous, and if you by mistake charge it on the wrong setting, the battery WILL EXPLODE or at least burst into violent and inextinguishable flames. Google li-ion battery fire video to see what it´s like.
I wouldn´t rely on a simple switch setting to decide if I set my house on fire or not, and it doesn´t even have to be you who puts the battery into the charger, could be wife or kid who doesn´t realize what can the wrong setting do..