Battery (Optima?) for 964 C4

[iamtheari]

Well, the battery in my new baby decided not to get me home today. It's been recommended that I get a red-top Optima. Of course, I went to the local auto parts store where I spent $180 on one after telling them my make, model, and year, and only after I get home do I realize that it's left-hand positive so it won't work in the 964. Is there an Optima battery that will? Bonus points if I can find it anywhere locally so I can drive the car with confidence on Easter weekend. Thanks.

[craig722]

I have a '92 and had to take back my Optima because the factory positive connector has a 90degree bend. The Optima's positive terminal is placed too far from the outside edge of the battery, so you can't get it connected. The guys at Advance auto parts looked it up on the computer and Optima doesn't make a replacement battery for the '92. What about an Odyssey? Google this one ODYSSEY Batteries - Dealer Locator
At least they make a model for the 964. Like everything Porsche it ain't cheap. ODYSSEY Batteries - Find a Battery
Take care

[iamtheari]

The 90-degree bend in the positive connector is exactly what I ran into when trying to mount the Optima group 34/78 battery backwards in the car. It fit fine and I could reach the terminals with the leads, but the positive connector wouldn't play nice. Odyssey batteries seem simply too expensive. More than $120 is already painful, more than $300 is just crazy. But I'll keep them in mind and do some research on whether they're worth the price to me. I probably have different climate needs than you do down there in the tropics.

[trak ratt]

I have yellow tops in both of our 964s. No issues with either car since all the electrical gremlins were tracked down. Some Optima batteries can be purchased with the terminals reversed if needed. Full size battery in wife's DD, small one in track car. Battery mounts were an easy fab too.

[perry911113]

I would put a Sonnenschein Dry cell in instead. They look and fit like OEM. I put them in my 72 911 (twin battery application).
The only place to get them is Fort Lauderdale Battery
see:
Sonnenschein Gel Cell Batteries
954 525 5557

The Optima's just don't fit.
My 2 cents.

Peter

[iamtheari]

What group #'s are those two Optimas you have? How much of a battery mount was required? The one I bought fit into the car perfectly and the clamp held it in place just fine. The positive lead having that nasty angle is the bigger concern so I want to be sure I get a battery that I can actually connect to the car. Thanks for the good news that it can be done!

[911Urge]

I have a Redtop battery in my 89 C4 and I used the factory battery mount.

Redtop Part# 75/35
Model - 9083561

[iamtheari]

I'm kind of surprised the 75/25 fits. According to Optima Battery Optima Batteries Free Shipping! Best Service! Deep Cycle Batteries Yellow Blue Red Top Optimum the 75/25 has the positive terminal on the left, which is the main problem with the 34/78 that I got from the local parts store. My reading is that I need a 34R or 35. Do you know if your positive battery cable has a hard 90-degree angle in it? That's what prevented me from putting the 34/78 in backwards.

[Traveller]

Originally Posted by iamtheari

Is there an Optima battery that will (fit)?

It doesn't have to be an Optima. I take it you want a so-called sealed battery. Have a look at an East Penn 9AGM48. They are an AGM battery. The case is 100% identical to the Porsche battery. I have the same one but in a flooded lead acid type.

Check this dealer listing to see if there is one located near you.

[iamtheari]

Optima is just the one that came highly recommended from a friend here who has them in all his cars. It's the starting point, not the ending one. East Penn's nearest dealer is 350 miles away in Wyoming, sadly, so I'd have to find it online and pay for shipping. It is still a viable option and the pricing seems reasonable, though.

[911Urge]

Mine has the 90 deg downwards bend on the positive cable. Photo included



The Redtop in my 1989 964 C4 is:

Redtop Part# 75/35
Model - 9083561

Picked mine up at Pep Boys and it was in stock. Good Luck and keep us posted as to what you decided to do.

[craig722]

Thanks to 911Urge for providing the picture. But that is the old design where the terminals
were closer to the outside edge of the battery case. Hit this link for a picture of the new design Optima Red Top Battery - RedTop Batteries by Optima As you can see they moved the terminals more into the middle of the battery and that 90 degree connector bumps into the case before it can reach the positive terminal. To use the new Optima, you have to cut off the 90 degree connector and have a straight one installed. Only problem is the length of the positive battery cable is pretty short and might not reach the terminal.

[Traveller]

Originally Posted by iamtheari

Optima is just the one that came highly recommended from a friend here who has them in all his cars.

Why does he highly recommend them? Based on their life? Does he get 8, 10 years out of them? Just curious.

The buyer for Costco in our region that I chatted with at a local P-car owner's home said he no longer carries them due to issues.

I would highly recommend Panasonic batteries. Why? Because the original batteries lasted 16+ years (when car was sold) and 12 years and still going in my present Honda. Unfortunately, Panasonic car batteries are a factory installed battery and cannot be sourced here.

[trak ratt]

Originally Posted by iamtheari

What group #'s are those two Optimas you have? How much of a battery mount was required? The one I bought fit into the car perfectly and the clamp held it in place just fine. The positive lead having that nasty angle is the bigger concern so I want to be sure I get a battery that I can actually connect to the car. Thanks for the good news that it can be done!

IIRC they were the D51 and D34. Was in a hurry so just made a cardboard template of the mounting location. Then cut some sheet metal mounts from the last of a rusty hood I had out back. Drilled 4 holes in the bottom sides of the batteries for some 10mm bolts. Secured battery/mount using stock rear lip and original battery mount on chassis.

Would be interested in how some used the stock mounts without an adapter?

[iamtheari]

Originally Posted by Traveller

Why does he highly recommend them? Based on their life? Does he get 8, 10 years out of them? Just curious.

The buyer for Costco in our region that I chatted with at a local P-car owner's home said he no longer carries them due to issues.

I would highly recommend Panasonic batteries. Why? Because the original batteries lasted 16+ years (when car was sold) and 12 years and still going in my present Honda. Unfortunately, Panasonic car batteries are a factory installed battery and cannot be sourced here.

My understanding is that he recommends them because of their life and their having never given him any trouble in the extreme cold. What issues did the Costco buyer you spoke to have with them?

[Jtilden]

Have you considered Interstate? I went from an Optima to Interstate in my cars based of the fact that the Interstate offers a 7 year warranty as opposed to Optima which is only a year. And the Optima in my wifes 993 was toast after only 3 years of service.

[Traveller]

Originally Posted by iamtheari

My understanding is that he recommends them because of their life and their having never given him any trouble in the extreme cold.

AGM batteries typically have a lower internal resistance and therefore a higher CCA, a spec related to starting ability in sub-freezing temperatures.

Originally Posted by iamtheari

What issues did the Costco buyer you spoke to have with them?

They were getting too many returns due to short life. Some of them could have been attributed to charging issues...but then that many, and if that is the case, then all manufacturers would be seeing that.

[canuck964]

I wouldn't recommend the red top Optima.

I just replaced mine after a year and a half in service.

I think that it has actually been bad since last year but the Porsche was sleeping in the garage all winter.

Wouldn't crank up the old beater on the weekend.

I had it hooked up to a battery tender all winter but just learned that you cannot use just any battery tender it has to work with the AGM type of batteries as they require more juice to recharge.

I just went back to the regular old type of sealed batteries from Interstate. Fits OK but the 90 degree bend in the positive terminal means it doesn't sit all the way down.

I did a lot more research after I installed the red top and it is generally noted that they do not perform well on Porsches that tend to be summer cars with limited milage. I only put about 500km per year on mine.

I'm so disappointed that I'm not even going to try and get a replacement even though it is within the 3 yr warranty period.

[iamtheari]

My P-car isn't a summer-only car. That's what my BMW motorcycle is for, and I feel guilty when I don't put enough miles on it. But the battery tender comment is duly noted. I think I will try to return the Optima to the store and get a different battery for the car. It does definitely need one, though. I had my battery tender on it for all but a couple hours from Tuesday evening through this morning and it still had the red "charging" LED on. It started right up this morning - we'll see how it does when I leave work without having had it on the tender during the day. But either way, I do want the confidence of a reliable battery in the car. It has a Duralast right now. It sounds like Interstate has proven itself to a few people here, at least.

[Traveller]

Originally Posted by iamtheari

I had my battery tender on it for all but a couple hours from Tuesday evening through this morning and it still had the red "charging" LED on.

Rely less on those "idiot" light on chargers and more on actual open-circuit voltage measurements using a digital multimeter that can be bought for well under $50. If you do, get one with a 10A DC input.

You should measure your current drain with the car locked and alarm set. Maybe you have a current drain that is discharging the battery. About 22 mA is normal in a 993...not sure about a 964. Bad batteries can also have a higher than normal self discharge, that would add to the issue.

Also measure your charging voltage once you get a new battery installed. Maybe your charging system isn't up to spec.

BTW, I'm not impressed with the BT brand.