Charging Batteries

[TorqueVR]

I've built an electic car for my grandson, which is powered by a pair of 12v mobility scooter batteries wired in series to give 24v to the motors. My charger is a standard car type 12v, which until now I've used to charge each battery individually. If I connect it to the pair of batteries will it charge slowly, or not at all?

[TorqueVR]

To clarify - 2 batteries, in series and they are GEL