Hi jtammerine, I noticed your original question and the subsequent replies and wanted to offer some assistance. Our BlueTop batteries are designed for marine applications, but as long as a battery fits properly (including venting provisions, if needed) and meets or exceeds OEM specs, any of our batteries can be used in automotive applications.
All Optimas with dark gray cases (all RedTops and the 34M BlueTop) are starting batteries, while all Optimas with light gray cases (all YellowTops and all BlueTops except the 34M) are true dual-purpose batteries, designed for both starting and deep-cycle applications.
If your vehicle has significant electrical upgrades or you like to run your stereo for long periods of time with the engine off, a battery designed for deep-cycle applications is appropriate. As joegr indicated, people shopping for batteries for such applications should focus more on reserve capacity than cranking amps. Even cold cranking amps are only a concern for folks who live in places where it gets cold.
nortyhat, Yellowtops can be charged with high output alternators. If you are running your dual batteries in parallel, they need to be the same age, size and type. If that is not the case, they need to be isolated from each other. Even though our batteries are sealed, it is important that any lead-acid battery has proper ventilation. ALL lead-acid batteries can vent gas. Traditional wet batteries do this immediately when recharged, since they are not sealed. Sealed lead-acid batteries like Optimas and all other “dry cell” AGM batteries have safety release valves that should only vent if they are seriously overcharged.
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. Optima 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.
I did take a look at pektel’s installation and while his venting provisions may be better than nothing at all, we cannot know the effectiveness of it and cannot endorse or recommend his method. One of the issues with venting methods of this type is that the polypropylene container doesn’t bond to too many materials, so it’s hard to get a good seal. Diameter and tube-length is also an important consideration. The vents on pektel’s battery were never intended to be attached to a tube in that way.
If you have any other battery-related questions, I’ll do my best to answer them.
Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.
www.facebook.com/optimabatteries