Open trunk without battery while installing Optima

[geoff]

The other weekend I finally got around to installing an Optima battery to replace the original 5 1/2 year old Porsche battery in our '05 997. I made a simple mounting base for the Optima 34R from 3/8" thick HDPE sheet. I plugged my CTEK 7000 battery maintainer in to the cigarette lighter socket hoping to maintain radio and other settings while I disconnected the battery. After removing the battery, I was amazed the trunk light stayed on, so just for grins I pulled the lever for the rear deck lid, and was amazed it actually popped open - without a battery. Then I pulled the lever for the front trunk and heard the click noise, even though the trunk was open. The bottom line is you can open the front trunk with a dead battery using one of these chargers, which has a built-in supply mode!

The Optima 34R fits in the 997 just as easily as in my 986. It's easier to remove the left and right plastic covers as well, and these come off easier than on a 9x8. The trick I remembered was to take off the ground cable, install the battery, then reinstall the ground cable and orient it so it's long enough. I tied off the vent tube out of the way in case I ever put in a conventional flooded battery. Otherwise it's just like installing any other battery.

I've got some of the 3/8" HDPE sheet left over, so if any RennTech contributing members near me want one, let me know and a piece is yours for as long as I have any material left.

Here are the pictures of the completed install

[1schoir]

The other weekend I finally got around to installing an Optima battery to replace the original 5 1/2 year old Porsche battery in our '05 997. I made a simple mounting base for the Optima 34R from 3/8" thick HDPE sheet. I plugged my CTEK 7000 battery maintainer in to the cigarette lighter socket hoping to maintain radio and other settings while I disconnected the battery. After removing the battery, I was amazed the trunk light stayed on, so just for grins I pulled the lever for the rear deck lid, and was amazed it actually popped open - without a battery. Then I pulled the lever for the front trunk and heard the click noise, even though the trunk was open. The bottom line is you can open the front trunk with a dead battery using one of these chargers, which has a built-in supply mode!

The Optima 34R fits in the 997 just as easily as in my 986. It's easier to remove the left and right plastic covers as well, and these come off easier than on a 9x8. The trick I remembered was to take off the ground cable, install the battery, then reinstall the ground cable and orient it so it's long enough. I tied off the vent tube out of the way in case I ever put in a conventional flooded battery. Otherwise it's just like installing any other battery.

I've got some of the 3/8" HDPE sheet left over, so if any RennTech contributing members near me want one, let me know and a piece is yours for as long as I have any material left.

Here are the pictures of the completed install

Nice install and excellent tips!

How is the battery fastened to the HDPE plate?

Regards, Maurice.

[geoff]

How is the battery fastened to the HDPE plate?

10-24 x 1 1/4" stainless steel flat head phillips head machine screws (quantity 4) from the bottom of the HDPE plate. The screws aligned with the holes on the Optima battery, then a washer and #10 stainless lock nut. I countersunk the screw holes so the heads were flush with the bottom of the plastic. Very simple, but easy to just unscrew the 4 screws in the future, replace the Optima with a new one, and then screw it back together. I made the mounting plate the same size as the old battery so I could just use the existing Porsche mounting clamp. It was about 12 1/4" x 6 7/8", same as I did for my 986 in this topic

I'm out of town all this week, but can post pictures when I get back of the mounting plate I made if anyone is interested

[1schoir]

How is the battery fastened to the HDPE plate?

10-24 x 1 1/4" stainless steel flat head phillips head machine screws (quantity 4) from the bottom of the HDPE plate. The screws aligned with the holes on the Optima battery, then a washer and #10 stainless lock nut. I countersunk the screw holes so the heads were flush with the bottom of the plastic. Very simple, but easy to just unscrew the 4 screws in the future, replace the Optima with a new one, and then screw it back together. I made the mounting plate the same size as the old battery so I could just use the existing Porsche mounting clamp. It was about 12 1/4" x 6 7/8", same as I did for my 986 in this topic

I'm out of town all this week, but can post pictures when I get back of the mounting plate I made if anyone is interested

Geoff:

Thanks for the detailed explanation. I didn't know the Optima had ears that you could screw into.

The more pics the better around here!

Regards, Maurice.

[wvicary]

It's not a good idea to be using a battery charger on a vehicle without a battery installed as the charger can spike in voltage and damage components.

[geoff]

It's not a good idea to be using a battery charger on a vehicle without a battery installed as the charger can spike in voltage and damage components.

I've got the CTEK 7000, but there's a slight update called the 7002. On CTEK's web site at http://www.ctek.com/EN-US/consumer/mus-7002.aspx they say "Thanks to its SUPPLY mode the battery charger provides power even without a battery. The SUPPLY mode is indispensable when changing the battery as you avoid losing complicated program settings." Based on their design with this functionality, I used it to keep from losing settings. The 7000 is a higher end version of their 3300 model, which is what Porsche rebrands and sells.

[wvicary]

Well I learn something new everyday. I know that battery chargers can cause problems but I still wouldn't use a maintainer and start operating locks/power windows and such just incase. I've never tested the output of these CTEK units so maybe they can be stable enough without problems.

[geoff]

Something I forgot to include in my original post: The original Porsche Moll battery weight 47.2 lbs when I measured it (not sure how much water evaporated from the cells), and the new Optima weighed 40.6 lbs. The mounting plate I made and fasteners weighed much less than a pound

[seadoxpl]

I would certainly pay you for a one of those setups. I'd love to ditch the Porsche battery . Please PM me if you would be so kind.