Hi Tim,
Great information already posted here. The fact that our batteries are sealed and won't leak or vent under normal operating conditions make them a great option for porsches. Whenever any battery is mounted in an enclosed space (trunk, interior, etc...) it should be properly-vented to the outside air, just in case of an overcharging situation. The only batteries we currently offer with external venting provisions are our Group 27, 51, 78, 34C, 31 & DS46B24R batteries. As far as charging a deeply-discharged Optima, yes, there are videos (hotlink to our parallel charging video) on the proper way to charge in parallel or simply use a microprocessor-controlled charger with a AGM setting. That way you will not overcharge or improperly charge your battery.
Jump-starting our battery won't necessarily harm it, but if it is deeply-discharged to the point that it needs a jump, it should be fully-recharged with a battery charger as soon as possible. Most alternators are designed to maintain batteries and relying on one to recharge a deeply-discharged battery can lead to a cycle of dead batteries and jump-starts, until either the battery or alternator fails. Optima has just announced we are selling our own brand charger, look for them on the market in the spring. I have seen one in person, and it goes the extra mile in not only charging a battery but does its own diagnostic tests whenever you first hook it up to be sure everything is ok.
Hopefully, this gives you all the information you will need to buy a replacement battery, but if you have other questions about our products, just ask.
Thanks,
Bill Howell
eCare Manager, OPTIMA Batteries, Inc.