ron mcatee

I currently have an MB66-60 Interstate battery with 550 CCA and 690 CA in my 88 911 (size is 11.38" X 6.88" X 6.88"). The car didn't start this morning , so I am charging it and hoping for a miracle. I think it is going south and am thinking of going with an Optima red top. The current battery is well below the original CCA of 850 CCA, but has worked well for four years. The only reason I went to the smaller one four years agon was due to size. The original battery was 14.38" long X 6.88" high X 6.88" wide. I had to remove the front condenser blower motor assembly every time i needed to remove the darn battery, so I opted for the smaller size and CCA capability.

Does anyone have any experience/knowledge of Optima batteries?, i,e., CCA limits, sizes, etc? I will be going to several places tomorrow to begin looking, but would like some feedback from fellow Rennlisters.

ked

I just went through this, replaced the heavy diesel U-Boat sized batt w/ an Optima Red Top (model #12853). So far so good. The Optima spec'd a little bit under the factory behemoth, but not enough to matter (to me & alot higher than your small interstate).
a) have batt acid cleaning & corrosion kits handy when you start.
b) you'll have to fabricate some kind of interface for the Optima to utilize the OEM batt hold down points (it's smaller! lighter!). I made a lexan plate, bolted the Optima down to it & voila! think through the positioning of the batt in ref terminals & the hold-down clamp. I also bought a 15" neg terminal cable to make it all reach w/o stress.
c) stand back & admire your work. fight urge to remove spare (damn thing weighs a ton!).

I recall reading / hearing somewhere that the Red Top might need a high load charging on occasion if you allow it to discharge over a long period. we shall see. cheers!

ron mcatee

ked, thanks for the reply. In my 38 years of driving Porsche's, I've always used the wet cell replacement batteries. Now with dry technology, I thought I would try an Optima unless there is a bunch of negative feed back. I always clean the battery area a couple of times a year so it is really clean in there now. I have a piece of cuting board i got from The Container Store just in case I go ahead with the Optima. I try to drive the 911 at least once a week or more. The old girl wouldn't start this morning so I pulled the battery and found there are two rectangular plugs that are removable (I was told it was a sealed battery). When I popped them off, the insdie of the battery was dry. I have filled the battery with distilled water and put a slow trickle charge on it with hopes of reviving it, but not holding my breath. 3 1/2 years in the Texas heat may have taken its toll on it.

Happy thanksgiving.
Spider911

pjc

I purchased an adaptor plate from Scott Nabb for $30 last year (shipping free in US at that time) - purpose built for the Optima - scott@ajusa.com. No affiliation.

I must confess that to date I have not fitted it because my wet battery is still OK but a friend was living in LA so he made the purchase and brought it back 'hand luggage' to the UK. A nice bit of kit.

PJC

ron mcatee

To all: Update: I filled the dry battery with distilled water and put a charge on it. To my surprise, it tested very good. Thanks to all who provided input to my possible dilemma. I have the inputs and will use them when the darn thing does crap out. It's not a matter of will it, but when. I also found there are two Optima Red Tops. One has 620 CCA and the other 800 CCA. I think the 800 is what I will go with when it does fail. Cost of them is $104.99 and $134.99, respectively. This is from the Interstate Battery Dealer here in San Antonio, TX. I doubt I can get one cheaper anywhere else. Again thanks for all the inputs.

ked

Great! Proves that "the ole college try" is usually worth it. When the time comes, go w/ the 800CCA, that is close to the fact spec - the other one may be fine for older 911s w/ fewer elect motors & accessories. I got mine at Costco for far less than $135.

Peter Zimmermann

Something to consider - the Sears DieHard is now an 8 year battery (in the smaller size - Group 48 - that fits the rearmost hold down bolt hole). It's a straight bolt in, retails at about $120, and has a CCA of 700. The car's stock terminals, ground strap and hold down fit perfectly. I'm not an advocate of any particular type of battery, I have the Sears unit in my SC because its purchase was convenient, so this is another option.
Pete

RoninLB

trash you're old battery and get a new one. Clean the lug terminals, use some dielectric or those donuts for a wet cell, and clean the chassis ground and add a dab of dielectric.

If your old battery faults sometimes bad things can happen that cost money.

der Mond

I have used an Optima Red Top in Alaska in a '89 Jeep Cherokee and started in -45 F. weather after 3 days w/o plug-in (Mobil1 0W-40 Synthetic). The Optima has a truly astounding amount of cold cranking reserve, and is slow to discharge. Of course, it will not leak fluid into your luggage compartment, a concern with 911's when the alternator goes bad. I recently installed one in my '87 911 w/ adapter plate from AJUSA. It required replacing the OEM negative battery cable w/ a 15" aftermarket one (NAPA works fine). The OEM battery cable terminal was straddled by the windshield washer tube and was a PIA to get loose, but do-able. The caveat with a Red Top is that if it is significantly discharged, you would do well to charge it with a plug-in charger first, since it takes quite a lot of current to charge when D/C. Better to not ask your alternator to make up the difference: my local alternator guy says it can lead to premature alternator failure. I am running a K3 Aussie alternator purchased from Pelican for about 17K miles now with no problem. It supposedly has a diode which will prevent overcharging in case of failure and the alternator light will give fair warning. We will see. It was beacoup expensive. A 911 is, like any vehicle, an experiment. That same alternator guy, by the way, says that for Interior Alaska, the best batteries he's seen in the ranks of mere mortals are Die Hard Gold, Motorcraft and Exide. I just put a Die Hard Gold in my '99 Dakota 5.2 and it works great.
Good luck!
Dennis

der Mond

BTW, the Optima I use is a Group 34 and I purchased it at Sears.

ron mcatee

der mond, thanks for the info.