Dumb battery question

[bcarey]

Apologies upfront for the simple battery question. I've done a bit of searching, but haven't found the exact detail, and I'd really like to avoid blowing myself up. The PO of my 1973 2002a left me with a dying 51R. I've learned that 42 is the appropriate replacement, but when I went to Costco I learned that they don't carry 42. I've read that 26 and 47 will also work, but do I need to set them up any differently? That is, if I'm installing in the front, do I need to worry about venting for the 26/42/47 batteries? Thanks!

[Hans]

Not such a dumb question. You might want to vent it to below battery bracket, but that means finding a fitting for the hole and a piece of tube. Try Walmart for a closed one at a reasonable price.

[John_in_VA]

I don't recall BMW supplying/requiring batteries being vented until they were situated under seats or in the trunk. I don't think the battery in my Beetle, under the right side of the rear seat bottom, was vented.

There is plenty of airflow under the hood of a 2002 to prevent gas build up.

[bcarey]

Yeah, that makes sense re airflow up front. Re: the differences between 26-42-47, will any of these cause harm to my system? It's currently stock, but I plan to add a radio and and fog lights down the road.

[Napes]

We use AutoZone #47 batteries in both my ' 75 and my wife's '76 and they work fine. Down here in Southern Arizona they last 6-7 years. The #s, I believe, refer to case size and 47s work fine in our cars.

Bob Napier

[John_in_VA]

As long it's 12 volts, the battery hold-down fits the battery case profile to keep it stationary, and the terminals/cables aren't touching any of the metal you should be good.

[dbmw2002]

My 2 bits worth is put the ground towards the nose, having that hot lead so close to the nose scaresme, as in come December if I plow a snow bank I dont want my o2 lightin up the sky like the Fourth of July

[roadhog0]

I run a Costco #12873 which is a group 58 and Costco fitment 8. The only downside is the terminals are on the fender side, but it's worked great for almost 4 years now!!

[c.d.iesel]

BMW part No. 61.21.7.567.181

50 AH

450 A (EN)

450 CCA (SAE)

9 1/2" long 6 3/4" wide 7" tall

fits front and rear

latest info:

bmw / DOUGLAS no. 10046-063W

61.21.7.567.181 50AH

$145 list as of 3/29/2013

last I heard - mine was 10 years old and still ticking . . . . . . .