Optima Battery Paranoia

[kang]

I just replaced my battery with an Optima Red Top. I chose this battery because of some advantages: supposedly won’t leak, lasts a long time, lighter, etc. But now I’m getting a bit paranoid. The Optima site says it “usually won’t outgas.” Is “usually” good enough? Joel Riser has this to say about outgassing and the Optima:

XXX sells the Optima for the 964 and they know how it fits there. The 993 battery fit is virtually identical. You will still need a vent line since charging is charging and it still produces hydrogen gas.

and

It is important to vent the hydrogen gas outside so it does not accumulate in the trunk. Hydrogen gas is highly explosive. Hydrogen gas is produced by normal charging of the battery, which always occurs while you drive the car at anything above maybe two or three thousand rpm. It also occurs whenever you have a charger connected when the car is sitting around.

Plus, it doesn’t fit quite as well as my previous battery.

Am I just being paranoid?

[Tom W]

I'd say so. The amount of hydrogen necessary to produce an explosion hazard (assuming absolutely no ventilation in the trunk) is likely a lot more than the battery could produce in normal conditions.

I haven't blown up yet and it's been a few years.

Note that Optimas need a hefty charger when they get depleted. If you battery is low, a trickle charger will not charge it. I got a charger that will charge at 12 amps. I had an electrical problem that was draining the battery and got very familiar with recharging Optimas.

[kang]

Thanks for the reassurance, Tom.

Mine doesn’t seem to fit very well. The side where the clamp is located is tight, but the opposite side, the side that tucks under the lip that’s built into the trunk, is a bit loose. I can lift that side of the battery up a small amount. It’s like the tongue on the battery is a bit small for the lip in the trunk. Does yours fit this way?

[Tom W]

Mine is held in by a metal clamp/strap to provide a more secure grasp of the battery for racing. For a street car, I would not worry about a little bit of wiggle. You could always add a small shim to provide a tighter fit too. (Small amount of lift means 1/8" or so?)

I just replaced the Otima with an Odyssey to reduce weight in the 964 too.

[kang]

Thanks again, yes, 1/8" or less. It’s not just the wiggle that worries me, it’s that the lip in the trunk doesn’t go over the base of the battery very well. I autocross regularly. I used to do DE’s, but I haven’t been in a while…

[NOH20]

So do you need to vent the battery?

[kang]

Well, the factory Porsche battery has a vent, as do other replacement batteries for this application, like the Sears Die Hard International. The Optima web site does not list a replacement battery for these cars...

The vent is there because the trunk is relatively sealed (compared to the engine compartment, where the battery is in most cars).

The Optima does not have a connection for the vent.

[aigel]

Even the NeverStart, I mean EverStart brand WalMart batteries have the vent. Not a bad idea on a lead acid battery if you throw the car around on track or ax, as that vent is where any acid would spill out and you don't want that in your trunk ...

George

[cupcar#12]

the optima is a Sealed battery - no vent
you can mount it upside down if you want

also there is an extened plastic mounting flang (cover, tie down, what ever you call it that holds the battery in) on the 964 and i presume the 993 would use the same peice.

[kang]

Originally posted by cupcar#12
the optima is a Sealed battery - no vent
you can mount it upside down if you want

also there is an extened plastic mounting flang (cover, tie down, what ever you call it that holds the battery in) on the 964 and i presume the 993 would use the same peice.

There is a lip in the trunk that the battery slides under. Is that what you are referring to by “extended plastic mounting flange?” I thought it was metal, but whatever. As I mentioned above, the part of the battery that fits under this flange was a bit small, and I could lift the battery up a bit. I solved this by the brute force method. I placed a long screwdriver between the battery and the wall of the trunk so that the tip of the screwdriver rested right on this lip. A couple whacks with a hammer pushed this lip down a bit, and now the battery is tight. I hit about three or four spots along the lip.

[cupcar#12]

No i was talking about the metal plate on the other side. that is replaced with the new extened plastic bit and then bolted down.
The Lip or flange is brute forced on all of them since the optima is slightly thicker at the base.

[kang]

Oh, OK, the clamp that gets bolted to the floor of the trunk. I have no problems with that. It seems to fit just fine. What new extended plastic bit are you talking about? I don't have one, nor does there seem to be a need for one.