Update by David S. Wallens to the
Porsche 911 Carrera project car
May 11, 2022
|
Porsche
Answer to the above question: At your mechanic’s shop.
Hey, our mechanic mentioned, our battery seems a bit weak.
How can that be? we replied. It’s not that old.
Turns out that “not that old” translates to nearly 12 years. Not bad for a mid-level Napa battery.
So where did the battery in our 1984 Porsche 911 Carrera finally give up the ghost? Home in the garage.
When we replaced that battery back in 2010, we substituted the stock group 49 battery with a slightly smaller group 91 battery. The battery tray has threaded mounts for both sizes.
This time, we wondered, maybe try something else–you know, in the name of editorial.
How about one of those Optima batteries? Is there really a difference?
A little while back, on the advice of BimmerWorld’s James Clay, we fit one into our BMW M3. Among his reasons for recommending Optima:
“Finally, and I swear this is huge: Optima batteries have cast-on straps. I've been through the plant and seen the operation–it's wild. Any other battery has welded straps–like internal wires to route the power.
“An Optima has a cast lead bus bar–thick and beefy. But more than that, instead of being welded onto the plate that is in the acid of a normal battery, they actually flip the battery upside-down late in the manufacturing process into a mold and then pour the molten lead in. It forms the straps and melts into the AGM plates or cells–depending on model–so there is no weld to fail.
“This is the common failure point of a battery and it is just totally eliminated with this manufacturing process. That's what allows an Optima to get beaten to death like we do on the track without failing.”
Okay, sold, let’s try one.
The Optima site doesn’t list a battery for our application, but comparing dimensions showed us that its Yellowtop DH6 should fit in our 911. This model shares its footprint with our group 91 battery yet measures about half an inch taller–we had the headspace.
Despite similar dimensions, however, the Optima does weigh more than the outgoing battery. “Because they pack it more efficiently and it has more lead than the comparable battery of the same size,” James told us when fitting an Optima in the M3, “so it's more effective.”
We ordered the Optima DH6 directly from its maker, and it showed up a few days later.
No issues with the post locations, either, and the factory mount easily grabbed the battery.
One thing left to do, however: We need to still clean up some of the wiring as we don’t like seeing all of those leads heading directly to the battery. Please don’t judge us, and fixing that is now on the to-do list.
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