here's a battery conversation going on in another forum, this appears to be a rep from optima--
Hello, I noticed your conversation regarding our batteries and wanted to offer some assistance. If you are drag racing without an alternator or use your fans or water pump in between runs, you should definitely be using a battery designed for deep-cycle applications, like our YellowTop. RedTops offer plenty of cranking amps for starting, but as Piledriver indicated, YellowTops and BlueTops (except for the 34M) are designed for deep-discharges.
I should also mention that even though our batteries have a “sealed” design, all lead-acid batteries can vent gas. Under normal operating conditions, an AGM battery will not vent gas. Since alternators or chargers can fail, the safest and correct mounting method for trunks and passenger compartments is to make sure that any possible gas venting will escape to the outside of the vehicle. All vehicles with original equipment battery locations in trunks or passenger compartments will have a vent provision that should be used.
Our group 27, 51, 78, 34C, and 31 batteries all have ports for connecting a vent hose. Although people do it anyway, we would never recommend installing an unvented battery in any enclosed space, because there’s a legitimate, albeit unlikely, safety risk involved.
For example, IF there is a voltage regulator failure, and IF the battery is severely overcharged, and IF this goes unnoticed, and IF the battery vents because the internal pressure exceeds the release pressure of the vents, the gasses are both flammable and toxic. This may sound like a lot of “ifs,” but attorneys and engineers get paid to plan for every worst-case scenario.
The quality of our batteries has always been excellent and has continued to improve, since Johnson Controls acquired us in 2000. Many of the “bad” batteries returned to us now are just deeply-discharged and work fine, when properly recharged. This is not a situation unique to Optima, in fact, some other manufacturers have elected to void the warranty on their batteries, if they are discharged below 10 volts.
In many of these cases, the owners probably didn’t realize that most battery chargers will not recognize or charge any battery that has been discharged below a certain voltage level. The threshold varies from one charger to another, but can often be as high as 10.5 volts. If a battery (of any brand) has been discharged below this level, the charger simply will not work. The parallel charging instructions explained in this video can effectively recharge many of those batteries-
http://www.youtube.com/watch?v=dIoaL3DWWEg
The key to long battery life, regardless of brand, is to make sure your battery is always at or above 12.4 volts. When batteries are discharged below that level and allowed to sit, sulfation begins to diminish both capacity and performance. That makes a quality battery tender or maintainer an excellent investment for any vehicle that is not driven daily. If you have any questions about our batteries, please don’t hesitate to ask.
Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.