Getting ready to take the T4S out for PCA meeting and its dead.

Bought the Walmart H7 Battery and when replacing I found the Vent Hose disconnected on the MOL battery.

Would a disconnected Vent House be cause for a battery to die?

Also BE CAREFUL when closing the door and your car has a dead battery. The windows don't go up and down like they are intended to. If I would have closed my door any harder I'm sure I would have broken the drivers side window. That should be a big warning when R&R the battery.

 

Unconnected vent hose should not have caused the battery to die...but corrosive fumes would have been vented into the battery compartment instead of outside so I'd check to see if you have any corrosion spots.

 

The venting of gasses from a battery are mostly hydrogen, so at worse you would have a hydrogen buildup in the are of the battery that might explode.

 

When mine failed, I replaced it with an Optima 34R sealed battery. Smaller size, better CCA, no maintenance, & no vent hose. Based on my experience with 4 previous Optima batteries, I should be good for about 5 years. You need to make sure you get the 34R and not the 34 as the R has the + & - terminals reversed so the factory battery cables will reach both.

 

I have an Optima red top in my truck and that battery has lasted at least 6 years. I'm amazed it has served me this long and it still continues to crank up first time, every time.

My 911 has the weak hot start problem. It's never failed to start but it sure does make you wonder if this will be the time it doesn't. I'd like to put an Optima battery in it soon. I think I'll have to look for one of those 34R batteries. I've seen how others on this forum have mounted theirs.

 

My local Advance Auto Parts actually had the 34R in stock. Here's a tip - if you go to their online site, they always have a coupon code at the top for 15% off + a future $25 store credit. If you order online and pick-up in store, you also don't pay a core charge and can keep your old battery to have a 12v power source for bench-testing auto or marine parts or you can wait for when Advance puts a coupon in their circular to bring in any old battery for $10 or $15 credit (I forget which). That puts you into the Optima for around $160. ($215 battery cost -15% ($32.25) - $25 future coupon). That's hard to beat. Who knows, maybe with the extra CCA it will help with your hot-start problem, although I think there's a TSB from Porsche on changing some of the cables that go to the battery to resolve that too. I'm sure you can search for it. Good Luck.

 

Thanks for the info and I don't mean to thread jack. I do know of the starter cable TSB and according to the maintenance records the previous owner of my car had the cable replaced already about 2 years/20K miles ago but it could be an issue again. Replacing the battery is an easy first step and could very well be the fix to my slow hot starts.

To the OP, I agree with others that the vent hose should not be the cause of your dead battery.