Early 911 Battery Options

[GotaT]

Its time for me to replace the battery in my 71. when I got the car it had a Regular 12v battery in the driver side battery box. I am wondering if there are any types of Tie downs for a regular sized 12v or if any of you have fabricated some good type of tie down for a standard size 12v.

Any pics or info is appreciated.

.... Are there any other options?

[nineball]

this is how i did it in my 83.

another battery install thread

[E Sully]

I installed the Westco Miata AGM batteries in my '73.5. You can find them online for about $110. shipped. No problems with venting or acid spills, and they fit right in the standard boxes.

[Scott at Pelican Parts]

I recently purchased a set of Interstate U911. Perfect fit.

Interstate U911

[cjmurph]

I did as Scott. U911 both sides. Fitment is tight though in my 71.

[cbush]

Any reason you are not going with the dual batteries? Works well, and good weight balance. Lots of sources for them. Downside is double the cost.

Chuck

[E Sully]

Westco Miata is slightly smaller than the interstate U911. Plus interstate is lead acid as opposed to Westco Miata being a gel battery. No corrosion of boxes or suspension pan. A bit lighter also. Fits battery boxes with a little room to spare. I bought 2, but one would have probably been fine. This is where I bought mine.
Westco Miata Battery with $9.95 SHIPPING!!

[GotaT]

Originally Posted by Scott at Pelican Parts

I recently purchased a set of Interstate U911. Perfect fit.

Interstate U911

To install the 2 12v U911 batteries whats the Correct Wiring ... Jumper wire from Positive lead to Positive and each ground terminal to the car where the wing nuts are? Or is it something different?

[nineball]

Originally Posted by GotaT

To install the 2 12v U911 batteries whats the Correct Wiring ... Jumper wire from Positive lead to Positive and each ground terminal to the car where the wing nuts are? Or is it something different?

yes that is correct. you can also connect the negatives and just use a single grounding point as well.

[69BahamaYellow]

I have been running dual lawn tractor batteries in mine for 3+ years with no problems in winter or summer. You can buy a 225 amp 12V lawn & garden battery for about $25 each, and they can be made to fit completely flush inside the battery boxes. You will have to file off about 1/4" of lead from the top of both posts and change your cable ends, but it works. You will also need to slip some thick plastic between the top of the positive post and the battery box to prevent contact.

[HarryD]

I went with a single Optima.

This thread has a good discussion:
duel battries

My thoughts are:

Sonnenschein is the way to go to keep the factory set up. You will need their DF75 (A512 /40 A) gel cells - Wholesale Battery Distributor - Retail Battery Distributor.

An alternative is go with a single Optima on it's side in one of the boxes and disconnect the excess wire.

Also, you can get the exact fit lead acid style ones from your Porsche dealer (New Editions - Classic Genuine Parts & Literature - Porsche Classic - Dr. Ing. h.c. F. Porsche AG). Look for: "Battery 12V 36Ah for the 911, Model: 911, Model Year: 1965-1973, Part number: 999 611 014 91, Availability: 01.03.2009". Pelican lists them at $189/ea and a special order.

An Interstate Battery U911 is also an exact fit.

There are other options such as Miata, Oddessy or Stinger batteries as well.

Also consider that unless your initials are M.S., chances are you will not detect a handling difference between a single and dual battery setup.

[69BahamaYellow]

The sealed Optima's are excellent batteries and was my original choice too, but I couldn't find one that would fit completely inside the battery boxes. The OEM dual batteries still hang outside of the battery box a bit and are super expensive, so that's why I ended up going with the small L&G batteries. I have added some pics of the lawn & garden dual battery option.

[dicklague]

Originally Posted by E Sully

Westco Miata is slightly smaller than the interstate U911. Plus interstate is lead acid as opposed to Westco Miata being a gel battery. No corrosion of boxes or suspension pan. A bit lighter also. Fits battery boxes with a little room to spare. I bought 2, but one would have probably been fine. This is where I bought mine.
Westco Miata Battery with $9.95 SHIPPING!!

I just ordered one of these and I am going to give it a try. I like the idea of the sealed battery, and I am happy it is smaller that the u911. I am going to start with one and see how it fits and then order another if I like the way it works. the cranking amps are more than the lead acid Interstate U911 and it is a bit smaller.

I will let you know.

I have one dead interstate just sitting on the passenger side as ballast and a going [will hold charge for 3 days] on the other.

[tim79euro]

LOVE the lawn and garden battery idea. that is fantastic! nice job!

[WANNA930]

Pep Boys carries Bosch Miata sealed batteries for about $100. Those Soenn whatever are just the internet rage. First off they have been backordered forever and besides everybody talking them up there is no real advantage to spend all that extra money.If you do a search you can see my Miata pic install.

The Interstate is shorter in height and fits the best. I have never in all the 30 years of playing with cars had a battery leak or explode so not sure what all the worries are. Take them out for the winter and put on trickle charger. Simple mat and you are done. If not throw in a Miata battery.

Is that a good idea to have one dead battery hooked up like that? Won't it always pull more to try and keep charge?

[E Sully]

I find it interesting that the red is used for ground and black for positive? I thought old british cars were the only ones with a positive ground.

[HarryD]

Originally Posted by WANNA930

Pep Boys carries Bosch Miata sealed batteries for about $100. Those Soenn whatever are just the internet rage. First off they have been backordered forever and besides everybody talking them up there is no real advantage to spend all that extra money.If you do a search you can see my Miata pic install.

The Interstate is shorter in height and fits the best. I have never in all the 30 years of playing with cars had a battery leak or explode so not sure what all the worries are. Take them out for the winter and put on trickle charger. Simple mat and you are done. If not throw in a Miata battery.

Is that a good idea to have one dead battery hooked up like that? Won't it always pull more to try and keep charge?

I have never had one explode but the corrosion from the acid fumes has weakend the metal in my boxes. Until I replaced the Interstate ones in my car, twice a year, I pulled them and neutralized/cleaned the damage from the fumes.

That is what drove me to a Optima.

[JerryL]

Great stuff, I need to dump the lead acid batt in the 71, have a optima in a 66 have been thinking about trying the westco, BUT have been so happy with the optima. 8 yrs + and going strong.
I am currently using 1 bat, removed the cross over hot and additional ground from the pass side.

Regards

[Slow911]

During Parade my batteries went out...but Interstate to the rescue with their new U-911 sealed battery....for $79.99 each.

[dicklague]

Originally Posted by WANNA930

Pep Boys carries Bosch Miata sealed batteries for about $100. T

Is that a good idea to have one dead battery hooked up like that? Won't it always pull more to try and keep charge?

I said it was ballast. It is not hooked up. That is how I know it is bad.....will drag the good one down. It have been unhooked for a bit, and now the good one is getting flaky.....I guess 4 years is a good run.

And that Pep Boys battery is a Bosch lead acid I believe.