A series connection will give you 24 volts. That's not likely gonna help. You can wire two or more batteries in parallel. It is best if they are of similar condition to prevent current flow between them (one trying to charge the other). This is really only a problem when the car is not running, so dual battery installations usually include an isolation switch to switch one of the batteries off line when the car is parked. John > Is it possible to add a second baterie to my 71, wired in a sires with the > other without causing any problems? Would it be better to wire it into a > paralell or series? > Thanks > Kevin Pacheco