rpatton3 is absolutely correct-
any lead-acid battery, Optima or otherwise, mounted in an enclosed space (interior or trunk), should be vented to the outside air. If a battery does vent in an extreme situation, those fumes are both toxic and flammable.
The key to long battery life, regardless of brand, is proper voltage maintenance. Fully-charged, our RedTops will measure about 12.6-12.8 volts and our YellowTops will measure about 13.0-13.2 volts. Whenever any battery is discharged below 12.4 volts and left sitting in that state, sulfation begins to form in the battery, which diminishes both capacity and lifespan. That makes a quality battery maintenance device an excellent investment for any vehicle that doesn't see regular use.
The quality of our products has always been excellent and the batteries we are making today are the best we have ever made. Many of the "bad" batteries returned to us today are just deeply-discharged and work fine, when properly-recharged. This is not unique to Optima and has become problematic enough for other AGM brands and manufacturers, that some will now void your warranty, if your battery is found to be discharged below a minimum voltage level.
We didn't do that with our warranty, but we now sponsor the Chumpcar World Series and give away these "AdOptimas" to the competitors to use in their race cars. If anyone has any questions about our batteries, I'll do my best to answer them.
Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.
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