Can I charge batteries with different voltages on a single charger, either a 12-volt or a 6-volt charger?
One of the answers to this question is a special case of the general question asked earlier about charging more than one battery at a time. That specific answer is that if the total nominal battery voltages of all of the batteries connected in series equals the nominal voltage output of the battery charger then you can use a single charger. For example, two 6-volt batteries connected in series can be recharged with a single 12-volt charger. Of course, all of the previous restrictions about charging batteries connected in series apply to this case. To this question answer more directly for single batteries, NEVER use a charger on a single battery unless the nominal output voltage of the charger matches the nominal battery voltage. For example, only use a 12-volt charger with a 12-volt battery. Do not use a 12-volt charger on a 6-volt battery or a 6-volt charger on a 12-volt battery. If the nominal charger voltage is larger than the nominal battery voltage, then the situation can become
