Battery Advice?

[WillM3]

Anybody have any advice on which battery to use? I left my lights on last night, and as a result have no battery today. Its an old Duralast that the PO put in, so I'd rather just replace it than recharge, etc.
I've heard a lot about Optima Orange Tops from the SIG archives, but I can't seem to find one anywhere. Will a different Optima work? Any other suggestions? Specific model numbers or specifications would be greatly appreciated.
Thanks,
Will
(Had to drive roommate's Durango to work today)

[wookie1976]

The factory BMW battery is what I run. I had the choice to buy anything out there and chose to go OEM since they fit perfect, last long, and keep the car stock. I have had Optima Red Tops and others in the past, but I dont feel that they are really all that special. If you insisit on aftermarket, go with interstate. They have a good warranty policy and the correct size.
My $.02

[Bryan]

Will,

I just went through the battery debate, and I decided to go with the smaller, lighter (almost 12lbs lighter) interstate battery. The only thing you have to do is modify the battery tray by drilling a small hole where the post should mount. You have to remove the battery tray which is easy. I have had no problems with it, and since it doesn't get that cold here in Texas, you don't really have to worry about the smaller battery. If you have a sound system, or have something that drains a lot of power, you might want to go with the regular interstate.

Here is the link to Gustave's site that tells about it: http://www.e30m3performance.com/inst...tt/sm_batt.htm

I was also looking at the optimas, but they are pretty expensive, and I didn't feel like going through the hassle of making a new mount and getting new cables and such.

[AdamF 88iS]

The best battery on the market is an Optima battery. I love mine. It's a gel battery so it doesn't need to be vented, and it won't leave a bunch of that white powder stuff everywhere. It also cannot spill. They last forever too. The downside is price.

You need the orange top, model 34R. It's the only one that will work. It fits in all directions, but it is little bit shorter than the stock battery in length.

Optima Batteries

[Magnus]

I love my Interstate MTP-91 battery and it fits perfectly into the tray with the hold-down bracket.

[m535is]

Do you have the BMW part# for the E30 M3 battery?

[mlytle]

I love my Interstate MTP-91 battery and it fits perfectly into the tray with the hold-down bracket.

+1
i run these in all my street bmw's.

the track/vintage M2 gets a 15lb Braille AGM.

[anm32nv]

OEM battery with bad cell

I just replaced my OEM battery today with an interstate --mtp-91 (114.99) as well. Dealer wanted 195 bucks for replacement. My OEM battery is less than 2 years old, as was added to vehicle by PO, but I have no receipt to take to dealer to get a new one, but mine has a bad cell. It shows green, but couldn't start the car. My first clue was the dim dome lights and dash lights. just my 2 cents in the event someone else runs into this problem with their OEM battery.

my OEM battery was part # 61 21 8 381 749 for those that were wondering

[BBS16]

Just to add to the above post, that Ive been through two batteries on mine. It seems that Bosch (when our cars were built) thought that around 13.5 volts would charge the battery ok well probably true with the batteries at the time but seems "modern" calcium ones need over 14 volts to fully charge. so may be worth keeping in mind?

[Jeremiah]

Pick up an adjustible voltage regulator then problem solved. I run a AGM BWM battery.

[NickB]

Pick up an adjustible voltage regulator then problem solved. I run a AGM BWM battery.

Do you have to get a specific one for our alternator? Do you have a part # or link to proper adjustable voltage regulators? Im having to carry a jumper box with me everywhere I go now because most of my drives are under 10 miles, and no highway. Im sure I could use a new battery too though.

[NickB]

Found it Here if anyone else is looking for these.