If you have two 6 volt batteries you can take a jumper wire and connect the negative post on one battery to the positive post on the other battery then connect the remaining pos and neg posts to the 12 volt battery charger.
No you cannot.
No.
You cannot use a 12 volt charger to charge 2.6 volt batteries. The 2.6 volt batteries will become hot, very quickly, and explode.
A twelve volt charger will charge twelve volt batteries only unless it has a feature that allows you to change the chargers voltage. But on fast or slow charge 12 volts is 12 volts so most 12 volt chargers are only good for 12 volt batteries.
Two six volt batteries in series makes 12 volts so switch the charger to the 12 volt position.
You would need a 24 volt charger. Connect them in parallel and you can charge them both with a 12 volt charger. Or disconnect them and charge each one separately.
You cannot do this. If it were a 36 volt charger you could connect three 12 volt batteries in series and charge all 3 at the same time. But this is a 32 volt charger which I have never heard of.
No you cannot.
Separate the 2 12 volt batteries and charge them individually.
A 10 amp charge will only output 10 amps and 12 volts. So, if you want to charge thee 12 volt batteries hooked in series you will have to disconnect the positive cable from each battery and charge then individually. You cannot charge three 12 volt batteries hooked in series. That requires a 36 volt charger.
No, since in series they are 24 volts so you need to charge each one independently with the 12 volt charger. This may be done disconnected or leave them connected and put the charger on the + - of the same battery.
how Can you charge multiple 12 volt batteries with a car?