Optima battery fitment

[eric16v]

Anybody using the Optima red top battery in their e30? What did you have to do for it to fit if anything? My battery is dead and I am thinking of going with optima if it will work.

[deansweet]

With it being the smaller footprint battery you may need to create yourself a longer (-) battery wire to get it to work but other than that I see no issue with using a Red Top?
Dean

[DesktopDave]

I used a yellow top for a while, but it wasn't designed for the car. Too tall and it didn't have the bottom cleat to fit the BMW battery tray. I had to bungee it into the car, LOL. I didn't have great luck with it but it was already on the way out. I've heard mixed reviews about the Optima batteries.

I've used a bunch of AGM batteries in my bikes though. If they'll last with the harsh conditions on a bike, they should run on a car for a long time. East Penn (Deka) makes an excellent AGM battery. I've also had pretty good luck with cheap old-fashioned Johnson Controls wet batteries (sold at WalMart as DuraLast brand among many others).

Next time I need a battery I'm going to upgrade it. RTS Auto claims a group 49 battery is a drop-in fit using the 2nd cleat mount. If that's true, the Deka group 49 Intimidator would work. I don't think Optima makes a group 49.

Found some great posts here and here.

[eric16v]

Thanks for the info. if I can remember correctly my original battery was a grp size 48. But when calling around the shops are giving me quotes on size 91. Does this seem right? Is 49 what is recommended?

[DesktopDave]

I'm not sure. To be totally honest, I'd just drive the car over to a battery shop and see what fits.

[keflaman]

I believe this is the one I recently bought for my car: http://www.batteriesplus.com/product/33897-SLI91T6M-Duracell-Gold-Battery/560-SLI/3951-Car-and-Truck-Batteries/650592-BMW/318is/1991-to-1995-L4-1-dot8L-600CCA.aspx

I checked around and compared prices/warranty between O'Reillys, Advance, Wal-Mart and Autozone. Batteries Plus got my business because of the three year free replacement followed by a 29 month pro-rated replacement policy. Prices were very close amongst all the vendors and they basically carried the same, rebadged battery. 

I have bought replacement batteries from Batteries Plus for my wife's X3, My Z3 Coupe, my E30, and a marine deep cycle battery for my emergency sump pump in the crawl space. I discovered the marine battery was dead two years after purchasing it. Batteries Plus took it back and issued me a free replacement just like the warranty stated. No drama. No hidden costs.

[doitover]

I've used an Odyssey PC-680. The first one couldn't start the car after a couple of years at sub 30. I terribly abused that battery though, draining it totally dead many times and once reverse connecting until, causeing one of the terminals to glow red. The current one has fared much better but it has only been a year or so. It is quite a bit smaller and lighter than what is supposed to be in there so doesn't fit the factory mounting.

[Slowered318]

Group 91 is the correct battery for the trunk of E30's (Group 48 is a little tall but will also fit). I would recommend a conventional battery, they work totally fine with the electrical system on older BMWs. I hear Costco offers a good warranty at a low price, the money you save is better spent to rebuild the alternator. No Optima will fit nicely and in my opinion their quality has taken a dive in recent years.

You can also shoehorn a Group 49 battery in there, only if your running a huge stereo or frequent drive-in movies. Otherwise it's just dead weight because the lights and fans are powered by the alternator when the engine is running. Battery is typically used only when starting the car and powering the door locks.

PS. Make sure you have a working vent hose.

[romeomike]

I've had the same Optima Redtop in my 91 318i for at least 10 years. The holddown will work just fine. Might need a slightly longer negative terminal battery cable.

Can't be more specific because the car is in the shop to change out the AC compressor and receiver/drier. Old unit was blowing fuses, new one unfortunately is doing the same thing for now.