Early 911 Battery issue/question:

[JackG]

Is there a better way to deal with the dual battery situation in early 911s, and the availability of dry cell batteries that will fit? In other words is it possible or advisable to install a single Optima battery and be done with it rather than dealing with the dual batteries? I realize the reasoning the factory initially did this, to balance the weight, etc., but now with more modern technology, etc., it sure would be nice to be able to use just one Optima. Plus, I don't want to install a wet battery for obvious reasons. This is, of course, not intended for a concours queen type of car.

Thanks for ideas!

[Allen Henderson]

Jack,

You can easily substitute one Optima, Odyssey or other modern, high cranking-amperage battery. You can place it on, say, the passenger side and be good to go. However, your car, under the front carpet, won't look or be in its original configuration. It really comes down to that, more or less all IMHO. Thanks.

Allen-

[jameshtaylor]

Sure. Two thoughts: just put one of the battery cables inside a plastic box and wrap it with tape so there's no chance of it hitting anything, and connect a battery to the other. Works fine; I did it for years with one Exide. I don't like Optima much; they are very big and heavy. Look at the much smaller 20 lb Braille 3121 as a candidate or the cheaper and very similar (maybe identical) Deka. Both use no-leak AGM technology like the Optima and have plenty of CCA for daily use. You'll have to customize your mount a bit to hold the smaller unit but it can go on its side if it makes it easier.

[304065]

Jack,

Sure, you can use a single battery. The factory did it for weight: there is no compelling electrical reason for two batteries.

THE battery to get is the Sonnenschien A512/40A. Available from http://www.sonnenschein.org, also known as Fort Lauderdale Battery. They cater to the marine community where the correct batteries, correctly installed and vented, are the difference between life and death, so they know what the hell they are doing.

The Sonnenschien is not cheap. Most batteries do not wear out, they are destroyed by the operator. If you treat the battery right, maintain the charge and don't do things like jump start the car (except in the case of a life or death emergency) it will give you many years of service.

In terms of the cable, you can unbolt the cable from the port-side clamp and remove it from the car. Mine is in the barn: the mice think it's a snake and stay clear. You could sell it to an "Audiophile" as a "high-end German Copper speaker wire" for $1,000. Train a dachsund to skip rope with it. The possibilities are endless.

Do NOT tape over the end of the cable and leave it in the car. A bit of tape is not enough to separate the business end of an 800 amp arc welder from your fuel tank.

I don't care for the Optimas at all, they don't fit in the battery boxes. Some people put them on the side to fit. In an accident, the positive terminal is going to short against the body sheetmetal, giving new meaning to the word "ignition points" and what could have been a minor repair becomes a total loss due to fire.

You see more bad engineering when it comes to battery mounts in our 911s, it's unbelievable. It's very important to use the factory rubber insulators on the positive terminal and the right hold-down clamps.

I'll get off the soap box about batteries now

[Allen Henderson]

Is nice ! Has worked well for over 30 years. Not expensive. Plug and play.

-Allen-

PS. I've installed expensive single batteries a couple times but have reverted to stock these days.

[Tom F.]

Is nice ! Has worked well for over 30 years. Not expensive. Plug and play.

-Allen-

PS. I've installed expensive single batteries a couple times but have reverted to stock these days.

The Interstates in my 71 were installed in 1998! That's pretty good battery life.

Like 30465 says, the rubber insulators are very important. I have had trouble finding plastic caps (the hinged ones that snap over the terminals) that will clear the rubber insulators, however. Anyone know a source?

[Allen Henderson]

The Interstates in my 71 were installed in 1998! That's pretty good battery life.

Like 30465 says, the rubber insulators are very important. I have had trouble finding plastic caps (the hinged ones that snap over the terminals) that will clear the rubber insulators, however. Anyone know a source?

I've not used both in recent memory at least The two would be a belt and suspenders, as they're both insulators, not to mention, that if the battery is properly, factory strap, tied down it is not going to short (but yes it could..if no caps). In any case, here are the factory parts, don't know if they are available. Let us know. Thanks.

-Allen-

[Mr9146]

In terms of the cable, you can unbolt the cable from the port-side clamp and remove it from the car. Mine is in the barn: the mice think it's a snake and stay clear. You could sell it to an "Audiophile" as a "high-end German Copper speaker wire" for $1,000. Train a dachsund to skip rope with it. The possibilities are endless.

I could really use that battery cable if it's uncut and you are willing to part with it.

PM me if you want it gone...

[Mr9146]

The Interstates in my 71 were installed in 1998! That's pretty good battery life.

Like 30465 says, the rubber insulators are very important. I have had trouble finding plastic caps (the hinged ones that snap over the terminals) that will clear the rubber insulators, however. Anyone know a source?

The new Interstates do not work with the rubbers. They now come with a perforated plastic flap that you will to modify, and there are no holes for the hinged caps. The new batteries from Interstate are black and are sealed ... they had a run of the white ones that started popping and they have since been superceded.

I collect those orange plastic, hinged covers and have never been able to fit one over a rubber instulator. BUT, I have put them in cars that have nothing...

And, to the original poster, I swear by a two-battery setup in a street car. There is no significant advantage to a single-battery setup in an early 911 if the battery is to be left in the battery box - routing it to the smuggler's box for weight distribution is really lame in a street car as it's totally unnecessary. Plus, the extra weight of the dual batteries in the nose helps the car handle better on the street.

[JackG]

Thanks everyone for your input. Marco, to your knowledge, does Interstate make a sealed battery that fits in our small space on each side on the early 911s? I guess when I last checked, there was such a limited choice available (Sonnenshine) when it comes to sealed batteries that will fit. And, I don't want any more batteries that have to have maintenance, ala wet cell.

Thanks, and if Interstate does, in fact, make one that will fit....if you have the model number that would be great!