Battery Replacement in a 86 - Advice Please

[darthracing]

Hi,
After 2 start failures over the last 2 weeks and confirming the voltage is low, I purchased a new battery from Kragen (ducking flames) this week
in hopes of putting it in this weekend (and to have as a backup until then).

I finally got around to installing it this evening, and my probem is that the new battery is physically much longer than what is in place now - its 14+ inches long (??!).

The current dying battery (yes, I hope the problem is the battery) is a "normal" size (10-11" long) Interstate AGM-800-S. I can't find any info on the web on this battery as to what its replacement should be.

I confirmed via several generic parts websites and all claim the proper replacement to be this 14" long monster. I see the forward braket hole for the longer battery, but I would not even be able to see (let alone tighten) the bracket in that position. Also, it looks like the battery will hit the big Clifford alarm siren and maybe the washer pump before I get that far.

SO WHAT is the current battery technology/manufacturer/dimension I should expect? Is this 14" monster the right thing to do or can I do better? Did the previous owner(s) go cheap or were they wiser than I? Do I really trust Kragen on this or take it back?

Suggestions? Car is driven usually only on weekends, in mild N. California climate. Car seems to keep starting as long as I run it daily a while.

Thanks
-Todd

ps: I am going to get one of the battery kill plugs at pelican

[strupgolf]

I had the same problem. I got a battery from a local auto parts store and they said the "factory size" was also the big 14". My old one was about 10". There is no way that the 14" was standard for a 86 model. I had to take my air cond. blower motor off to get it in, but since my air does not work, and I dont need it, I kept it off. But after looking at the hold down screw hole on the front, it looks like it might be the bigger battery. The small one slid around too much, and now I have the big one tied down really tight.

[lally911]

The original batteries were that huge but you don't need to replace it with another huge monster. Even Sears has die hards for European cars that have the necessary ridges on the ends to work with the battery clamp downs. Get a normal size battery and use the clamp down in the hole thats part way back in the battery tray.

[einreb]

If your '86 is the same as my '88 (I suspect it is), then there will be two different holes that you can bolt down the battery. One is about 10" and the other is 14".

Your post promted me to post pics of my recent battery 'solution' here...

My $10 Odyssey Battery mounting solution

[Wil Ferch]

Actually there are *three* different holes for the front-most mount...to allow three different battery sizes, IIRC. Maybe only two...have to check.

The big guy is a group 49 /93...the smaller version is ( I believe) a group 48/91...

I've posted about this many times before so let me check. I'll report back if I find it.

hint...being a "normal" battery, I would advise a way to add a vent tube to the battery and vent the offending acid fumes out of the car. hopefully this battery you have has the small vent nozzle that you can easily attach some tygon tubing to. Acid spills are *right* over the front suspension mount, and the fumes do no good for the nearby exposed copper of the fuse box...bad design / battery location choice by Porsche for this "normal" style of battery.

- Wil

Look here--> Anyone ever install an Interstate MTP93

and here ---> ( with size chart) Huge battery in 86 Coupe

...there are more with "battery" as a search word

[darthracing]

Thanks all, looks like the previous owner read the FAQ

I'll return the monster battery tomorrow while the current one still makes current - not risking the alternator if I can help it!

[Wil Ferch]

You can keep the big battery if you wish....the car pretty much came delivered that way. A smaller battery will put less of a "topping up" load on the alternator..a point that Loren correctly brings up in one of the threads. Use of a a float charger when the car sits, helps this situation.

Wil

[rouxroux]

Having replaced batteries in both our '86's this last year, here's 2 that will work with no problem...Energizer 49-850 (very close to the original size, even though the catalog showed a different size that was too large), and the Bosch 48-700B (fits with room to spare)...Hope these help.