Another Battery Post

[Roswell]

I need to replace my battery. '88 Carrera. What is the best plug and play option? I do not want to modify anything, just pull out the old battery and replace it with best new technology available today. Thanks!!

[wwest]

Went to Costco for the new one in my '88 Carrera....

[cantdrv55]

I went to Pep Boys and bought the smaller Bosch that's recommended for our cars. Completely plug and play.

[Larry Marshall]

About 2 weeks ago I found what appears to be the perfect solution for battery replacement for my 911 3.2 cars and 993s. It was at Costco, Smokey Point, WA. The battery is their #10, and has the vent capability and a tag stating that it is made in Germany. You'll need to buy a vent tube kit if you want to use it in your Carrera. The vent tube is standard in the 993s and easy to install in the Carrera and can save your battery box. Costco's battery guide lists their #10 battery as proper fitment for 1989 Porsche Speedster. Their price is less than $80 plus tax. I don't know what the life expectancy is but it has a 3 year full warranty. What a deal!!! Larry

[kach22i]

I picked up an Odyssey 925 not long ago, can be mounted just about anywhere including the stock location.

However some fancy mounting hardware may be required, plus best if kept on a trickle charger.

Perhaps not what you are looking for.

I will be willing to part with my massive lead/acid battery in a few weeks, but it's ten years old already.

It's never going to die.

[darrin]

I used a group 48 battery (auto zone sells the same size as an H-6) that's slightly shorter (and lighter) than my original battery -- significantly, the battery tray has a hole that let me use the hold down for the shorter battery without issue.

The battery I bought is an AGM (advanced glass mat) battery that uses the same technology (or so I understand) as the optima batteries -- it encases the acid in a glass mat that won't leak, etc. So, I feel I have the best of both worlds, a battery that has the advantages of an optima without the need to perform mods, etc.

[kach22i]

Originally Posted by darrin

I used a group 48 battery (auto zone sells the same size as an H-6) that's slightly shorter (and lighter) than my original battery -- significantly, the battery tray has a hole that let me use the hold down for the shorter battery without issue.

The battery I bought is an AGM (advanced glass mat) battery that uses the same technology (or so I understand) as the optima batteries -- it encases the acid in a glass mat that won't leak, etc. So, I feel I have the best of both worlds, a battery that has the advantages of an optima without the need to perform mods, etc.

The AGM's I looked at in the local store were not sealed, and I assume required venting.

Still an very attractive alternate.

Gray casing if I recall correctly.

[Danny_Ocean]

I discovered not too long ago that Odyssey and Sears share the same manufacturer for their AGM batteries. Odyssey battery? $300+. Sears Diehard AGM Gold? $179 (plus a few coupons got it down to around $150):

Sears.com

[Roswell]

Originally Posted by Danny_Ocean

I discovered not too long ago that Odyssey and Sears share the same manufacturer for their AGM batteries. Odyssey battery? $300+. Sears Diehard AGM Gold? $179 (plus a few coupons got it down to around $150):

Sears.com

Thanks Danny! Looks like I will be heading to Sears tomorrow.

[Danny_Ocean]

Originally Posted by Roswell

Thanks Danny! Looks like I will be heading to Sears tomorrow.

Double-check sizes, terminal positioning, etc. before purchasing anything. The story I shared was for my work truck, not my 911 (although the Sears fitment tool indicates the battery in my link is correct).

[darrin]

I'd still recommend going with the group 48 die hard over the larger group 49 -- much easier to get into position and provides more than enough power for my (any foreseeable) use -- Sears.com

Also, though obvious to many, it wasn't immediately obvious to me -- be sure to remove the negative cable first, this takes the battery off the car's electrical circuit and makes it a "no brainer" to remove the positive connector that's located right next to the body and would be very difficult to remove without otherwise shorting to the body . . .

[Danny_Ocean]

Originally Posted by darrin

-- be sure to remove the negative cable first, this takes the battery off the car's electrical circuit and makes it a "no brainer" to remove the positive connector that's located right next to the body and would be very difficult to remove without otherwise shorting to the body . . .

Or you could just flip it... Be sure to buy battery with "reversed" terminals. (not my car, but same set-up)

[wwest]

Originally Posted by darrin

I used a group 48 battery (auto zone sells the same size as an H-6) that's slightly shorter (and lighter) than my original battery -- significantly, the battery tray has a hole that let me use the hold down for the shorter battery without issue.

The battery I bought is an AGM (advanced glass mat) battery that uses the same technology (or so I understand) as the optima batteries -- it encases the acid in a glass mat that won't leak, etc. So, I feel I have the best of both worlds, a battery that has the advantages of an optima without the need to perform mods, etc.

"..glass mat that won't leak, ect.

No, it just builds up enough gas pressure to......


EXPLODE!

Common lead/acid batteries are designed to outgas rather than..

And will give you lots of odiferous warning if they're being overcharged or carrying to heavy a load.

[kach22i]

Any documented cases of this happening in a 911?

[darrin]

here's what I found on the mechanics of an AGM battery:

How does a gel cell work? A gel cell is a "recombinant" battery. This means that the oxygen that is normally produced on the positive plate in all lead-acid battery recombines with the hydrogen given off by the negative plate. The "recombination" of hydrogen and oxygen produces water (H2O), which replaces the moisture in the battery. Therefore, the battery is maintenance-free, as it never needs watering.

The oxygen is trapped in the cell by special pressurized sealing vents. It travels to the negative plate through tiny fissures or cracks in the gelled electrolyte.

The sealing vent is critical to the performance of the gel cell. The cell must maintain a positive internal pressure. Otherwise the recombination of the gasses will not take place, and the cell will dry out and not perform.

In addition, the valve must safely release any excess pressure that may be produced during overcharging. Otherwise, the cell would be irreparably damaged.

It's important to note that gel cell must never be opened. If opened, the cell loses its pressure, and the outside air will "poison" the plates and cause an imbalance that destroys the recombination chemistry.


And this appears to address the question of can it vent, and how to store:

Quote
Can gel cells be installed in sealed battery boxes?
NO! Never install any type of battery in completely sealed container. Although the normal gasses (oxygen and hydrogen) produced in a gel cell battery will be recombined and not escape. Oxygen and Hydrogen will escape from the battery in an Overcharge condition.
For safety, these potentially explosive gasses must be allowed to vent to the atmosphere and must never be trapped in a tightly enclosed space!

So, it appears the manufacturer says roughly:
1. The batteries do not vent under normal use, but
2. Do have a pressure relief mechanism that will allow them to vent and not explode in an overcharging situation.

[kach22i]

AGM is not a gell cell, two different technologies.

Optima is a gell cell, not Odessey.

[Halm]

Originally Posted by kach22i

I picked up an Odyssey 925 not long ago, can be mounted just about anywhere including the stock location.

However some fancy mounting hardware may be required, plus best if kept on a trickle charger.It's never going to die.

I just got an Odyssey as well along with the fancy hardware.

I have not seen or heard about the need for a trickle charger. Is this from experience or something I may have missed in the literature?

Thanks.

[darrin]

true, but both AGM and gell cells use the same recombinant technology to capture the hydrogen (and oxygen) released during charging and recreate water (making them truly maintenance free) and contain the same pressure relief apparatus necessary to prevent the explosions referenced above. see, e.g. absorbed glass mat (AGM) battery

[MSUConrad]

I just had to buy one yesterday. Pulled into AutoZone, and the salesman had a Gold series battery bolted down in about 10 min. Cost about $150, and is rated for 900 CCA.

Normally would have done a ton of research first........but when your battery shorts after pumping gas and Autozone is across the street......

[Racekar]

AGM all the way