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Thread: Problem with Porsche Moll Batteries

  1. #1
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    Problem with Porsche Moll Batteries

    Back in May of 2015 I purchased a pair of the Porsche Moll batteries (911-611-036-20) from our esteemed Ohio vintage parts supplier. I am doing a “correct” ‘70E restoration and wanted the vintage look as shown in the 700 mile ‘70S photos.

    I had them filled at my local reliable NAPA and then charged one on my smart charger. All seemed good and the charger indicated fully charged. I then used the charged battery to test components in the electrical system as I tested and reassembled them into the car. All seemed good until I got to the snail horns. The recharged Moll would barely make them vibrate while the battery in my Honda Ridgeline whould make them honk correctly. Something funny there. This week I did some final checks on the electrical with the recharged battery and found the wipers barely move, the horns would only vibrate and the flashers were really slow. Something wrong with this “new” battery? I then ran jumper cable from my truck battery to the Porsche and everything worked as it should.

    Since I don’t have a battery tester, I took the batteries back to NAPA for testing and recharge. The one I had been using overheated and the charge was aborted. Test showed only 6 volts and a bad cell. The second battery would only partially charge after 24 hours and tested at only 10 CCA compared to a rated 500 CCA. Both batteries bad.

    I will be calling the battery supplier on Monday to see how I can be compensated. In the meantime, I need to explore another option for batteries. I have a single Sonnenschein in my RSR and have been happy with it.
    Any suggestions on how to maintain the vintage look with a modern gell cell battery?
    Tom Butler
    1973 RSR Clone
    1970 911E
    914-6 GT Clone in Progress

  2. #2
    They're made by humans....so anything can go wrong randomly.

    I've installed four sets of the "factory" batteries in my and friends' cars without issue.

    Luck of the draw......unless I'm the lucky one and everyone else had crappy batteries!
    Mark Smedley
    '59 VW Typ I
    '69 911T 2.7
    '86 930
    '04 GT3
    '16 Boxster GTS
    '08 MBZ AMG CLK 63 Black Series

  3. #3
    Senior Member beh911's Avatar
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    I just replaced the factory Molls in my car that had lasted since August 2010 (7.5 years).

    Probably could have gotten a few more months out of them but didn't want to risk turning the key to start somewhere and having no cranking amps

    So they are high quality if you don't get a bad one like you apparently did
    1969 S Coupe #761
    Early S Registry #1624

  4. #4
    Same! I got 8 years out of my 1st set. I had to go back to my receipts as I didn't believe they were that old. Kept them on a Deltron Battery Tender that ran 2 hours a day on a lamp timer. An electronics guru advised not to just let the Tender run...only a couple hours a day. I have seven cars maintained the way, and all have batteries that have gone five years plus...just mind the fluid levels.
    Mark Smedley
    '59 VW Typ I
    '69 911T 2.7
    '86 930
    '04 GT3
    '16 Boxster GTS
    '08 MBZ AMG CLK 63 Black Series

  5. #5
    Tom I just purchased 2 MBZ batteries on my brothers recommendation. They are very similar in size to the 911 battery, readily available, and can be pretty easily de badged. They are white in color and I believe for the modern SL's so they have plenty of grunt. If you are interested in going that route PM me and I'll get you the part number. They're a bit shorter so they'll require a dense foam block underneath each one, but it was very easy to cut and fit the foam spacer. Cheers Steve
    1969 911 E #824

  6. #6
    There are advanced chargers nowadays that maintain a charge without "over-doing" it. I've got them on everything and so far no issues. Desulfating battery chargers are a good option.
    "Be who you are and say what you feel because those who mind don't matter and those who matter don't mind." - Dr. Seuss
    "Experience is the mother of wisdom" - idiom
    "Let them that don't want none, have memories of not gettin' any"- Brother Dave Gardner

    Early S Registry #235
    rgruppe #111

  7. #7
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    It sounds like "luck of the draw" that I got two bad Porsche batteries. Hard to to imagine unless they had a bad batch. We'll see what the supplier says tomorrow.
    Tom Butler
    1973 RSR Clone
    1970 911E
    914-6 GT Clone in Progress

  8. #8
    Quote Originally Posted by tom1394racing View Post
    It sounds like "luck of the draw" that I got two bad Porsche batteries. Hard to to imagine unless they had a bad batch. We'll see what the supplier says tomorrow.
    Good luck! Keep us apprised of your findings.
    "Be who you are and say what you feel because those who mind don't matter and those who matter don't mind." - Dr. Seuss
    "Experience is the mother of wisdom" - idiom
    "Let them that don't want none, have memories of not gettin' any"- Brother Dave Gardner

    Early S Registry #235
    rgruppe #111

  9. #9
    Senior Member BrentF's Avatar
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    Quote Originally Posted by xpensivewino View Post
    Tom I just purchased 2 MBZ batteries on my brothers recommendation. They are very similar in size to the 911 battery, readily available, and can be pretty easily de badged. They are white in color and I believe for the modern SL's so they have plenty of grunt. If you are interested in going that route PM me and I'll get you the part number. They're a bit shorter so they'll require a dense foam block underneath each one, but it was very easy to cut and fit the foam spacer. Cheers Steve
    Steve: Please post the part number. Thanks!
    Brent
    '70 911S
    '68 TR250

  10. #10
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    In researching this a bit more I have come to the conclusion that my problem was not defective batteries but the fact that the batteries sat for for almost 2 1/2 years filled but not fully charged. I purchased these in June of 2015, filled both and charged one. I used the charged battery for various electrical tests over that period but did not attempt to recharge it until this past December. The other battery was never charged.

    These lead-acid batteries do not like to be fully discharged and do not like to stay fully discharged for any period of time. This leads to sulphation. That is why we use battery tenders. Lesson learned, don’t buy lead acid batteries for a long term restoration project until you are ready to use them in a running car where they will be continually discharging and recharging. Alternatively, as we already know, keep your batteries on some type of battery tender for any long term storage. An expensive lesson for me.
    Last edited by tom1394racing; 01-29-2018 at 06:15 AM.
    Tom Butler
    1973 RSR Clone
    1970 911E
    914-6 GT Clone in Progress

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