car batteries

[crispyboy]

I need to replace the battery in my wifes' 2002 Grand Cherokee.
I usually go for the biggest lead acid battery that will fit when I replace the battery. A battery of 850 cca seems to have a free replacement up to 1.5 years and prorated warranty thereafter.
I was looking around the net this morning and I noticed that there are more AGM (absorbed glass mat) batteries on the market. A Diehard platinum battery has a free replacement period of 4 years and prorated there after.
Are these worth the extra expense (double the cost)?
Is an AGM type battery still subject to corrosion around the terminals?

[mutcth]

An AGM battery is typically more durable - the design is better able to withstand the vibration and heat cycling that can kill batteries. The Sears AGMs perform quite well. But like you said, there's a big price jump.

In the same vein - don't buy more CCA than you really need. To get that higher number, you need more and thinner plates, which can be more fragile.

Tom

[Jim Foster]

Five years ago I replaced the battery in our '66 Mustang with a 100 month battery from Costco. The car sits way too much, which is very hard on the battery. It took a dump last week, so I returned it to Costco. They gave me 20% toward a new battery.

20% after five years. I think that's more than fair. Good people.

[Mexray]

Battery warranties, in general, are sales gimmicks...being in the battery sales biz, I always recommend buying the heaviest battery of the version you need, for longest service life...

Normally, most batteries sold by 'reputable' outlets, last for years, regardless of the 'stated warranty' - if the new battery performs upon installation, you'll be in for years of service...if it should crap-out from a mfg's defect, it will most likely show up right away and be covered by even the shortest of standard warranties...failures years down the road are mostly maintenance related - deep discharge with lights left on; alternator charging issues; corroded connections; undercharge condition issues due to non-use, etc...and finally plate crumbling issues due to old age...

As to the CCA (Cold Cranking Amps - rating @ 0 degrees), or CA (Cranking Amps - rating at 32 degrees)...get the highest rating for the best battery or longest life - higher CCA batteries ARE NOT more fragile - if you compare CCA's in the same battery group number, the lower CCA battery will have fewer plates and some empty space inside that you can't see - the highest CCA battery will have the entire inside case filled with plates, or a FULL Plated battery, as we refer to them - BOTH batteries will have the SAME plates - the only difference will the be amount of plates inside!

Your Grand Cherokee uses a Group 65 battery , as I recall, and I don't think you'll find that GROUP size in AGM types - some outlets may offer one that's actually another Group Size (smaller), with some kind of plastic adapters to make it fit where a Group 65 resides...I wouldn't use anything but the correct Group Size in your vehicle -

I'd go for a Gr-65 with at least 850 CCA rating, to insure longest, trouble free life...

Buy a couple of those small donut shaped felt pads to place onto the battery posts before you reattach the cables - you can spray some WD-40 like stuff when the cables are in place, and the felt pads will keep the cable clamps coated underneath to form a barrier against corrosion - reapply some WD-40 every 3 months or so...I like to spray the hold down bolts and nets with the WD-40 at the same time to help keep them lubricated, as well...

Ray, the American Battery guy in Stockton, CA

[bryanl]

re: "To get that higher number, you need more and thinner plates, which can be more fragile." -- not so much with modern batteries.

re: "Battery warranties, in general, are sales gimmicks" -- being as a warranty is a legal agreement, it is about the only battery specification you can really depend upon. But, as Ray notes, it is usually (or should be) a moot point unless you run your battery flat a lot or drive short trips in cold weather at night or do other abusive things.

Battery life depends mostly upon use and maintenance. For the most part, car batteries have fairly well known use patterns which is why they have longer warranties than RV batteries.

There is generally no need to exceed manufacturer's recommended specifications for your vehicle unless the cost difference is negligible or you gain in some other area such as retailer reputation or warranty.

[2airishuman]

Originally Posted by crispyboy

I need to replace the battery in my wifes' 2002 Grand Cherokee...

IF replacing the OEM battery, 8 years is pretty good service.

look for whoever made THAT battery and get another one.

i use a schmear of di'lectric grease on the terminals and posts which seems to eliminate crud growing there.

and agree with the others above who suggest STICKING to the oem CCA...

and do NOT think agm design is needed in most daily drivers.

cheers
2air'

[crispyboy]

After checking around I can't justify spending more than 2x for an AGM battery even with all it's attributes. The AGM was $190. (diehard platinum)
I think I'll go with the same brand I usually get at the local parts house. It is a DEKA brand made by East Penn. It is a 70 month, group 65, CCA 850, 3 year free replacement warranty for $95.
As far as CCA's go I always upgrade if possible. It always nice to have the starter turn over at top speed on cold winter mornings. I have often seen stock size battery's undersized.
Thank you all for your opinion - this board is great for these issues.

Steve

[crispyboy]

The battery price only came out to $79.50 plus tax and the core- it was a good day!
Maybe when the market gets more competitive on the agm's I'll upgrade to one of those batteries.