January 06, 2009 11:47AM
It's time for a new battery in my 87 325ic. The current one was the house brand from AutoZone, and lasted about 5.5 years. I think I am hard on batteries since this is not my primary car, and it sits for weeks at a time during the winter. I don't have power nearby, or I would run a battery tender of some type on it.

I am thinking about putting in an Optima brand gel battery. They cost 2X or more over the standard premium 12V, but are supposed to last twice as long, and hold a charge well over long periods of non-use.

Does anybody have any experience, good or bad, with the Optima battery? Any other battery recommendations?

Andy
1987 325ic
January 06, 2009 12:03PM
Quote
akstraw
It's time for a new battery in my 87 325ic. The current one was the house brand from AutoZone, and lasted about 5.5 years. I think I am hard on batteries since this is not my primary car, and it sits for weeks at a time during the winter. I don't have power nearby, or I would run a battery tender of some type on it.

I am thinking about putting in an Optima brand gel battery. They cost 2X or more over the standard premium 12V, but are supposed to last twice as long, and hold a charge well over long periods of non-use.

Does anybody have any experience, good or bad, with the Optima battery? Any other battery recommendations?

If the battery has to be replaced then I would simply buy the regular type. The basic difference in the 3 year battery and the life time battery is the warranty; there is little difference in the construction other than cranking Amp power. You end up paying the same in the long run.

For the car that sits for long periods of time, you can buy an inexpensive solar panel that will keep the battery nicely topped up and in good condition. Well, unless you park it in a dark place.
January 06, 2009 10:07PM
Well, the Gel Cells are actually quite different than the regular batteries but the best part about Gel Cells is their ability to be tipped at extreme angles like boating or off-roading (and I think they have a greater power/size ratio). Obviously this isn't a concern for you in your 325, so personally I would just save the money and get a regular battery. I am partial to Interstates myself and they shouldn't be too expensive.
January 06, 2009 11:11PM
The Optima battery, along with the Odyssey, WestCo, and a few others, is not a gel cell. It's an AGM (absorbed glass mat) battery, where the acid is absorbed by a big mass of fiberglass. But either way, the important thing is that it's not a wet cell battery. Wet cell batteries generate hydrogen gas, which is why the original E30 batteries were vented to the outside. (Other cars with batteries in the trunk also need vents.) Putting an unvented wet-cell battery in the trunk will release hydrogen into the trunk. Lots of people (me included) have done it anyway, and the risk of anything bad happening is small, but greater than zero.

My Mazda Miata also has the battery in the trunk, and I use an Odyssey battery in that car. When I replace the E30's battery, it will also get an AGM battery. It's just one less thing to worry about.

__________
Dave
'91 325iX
January 06, 2009 11:55PM
I just recently replaced the battery in my 325iC from Interstate distribution store. I squawked a bit about the price since it was higher than Costco, The clerk suggested a Blemished battery...which looked a lot like the real one but with the lable removed and a generic lable stuck on it. Cost was about half the regular price with a two year guarentee instead of a 5 year. My old Interstate battery lasted about 7 years.

Bob in Everett



Edited 1 time(s). Last edit at 01/06/2009 11:56PM by Bob in Everett.
January 07, 2009 01:34AM
I think it just depends on the particular battery. I remember being surprised how much more expensive the one for my jeep was than the one for my range rover which was twice its size.
January 07, 2009 09:49AM
I think I'll just go with the AutoZone replacement. I will get a 15% or so credit because it was a 7-year battery. The solar battery tender is a good idea; I hadn't thought of that. By the way, the convertible battery is under the hood. Not sure why BMW put them in the trunk for other models. (Also not sure why I get a 15 lb block of cast iron in my trunk ?) It must have been a Monday morning when they engineered that.

Andy
1987 325ic
January 07, 2009 10:34AM
Quote
akstraw
By the way, the convertible battery is under the hood. Not sure why BMW put them in the trunk for other models.
Usually it's done for F/R weight distribution -- I can only assume that BMW did it in the E30 for the same reason.

I forgot that the iC has the battery in the front. The iC is about 150-250 pounds heavier than other models, so I guess the weight distribution is different enough that it made more sense to put it up front.

__________
Dave
'91 325iX
January 07, 2009 10:47AM
Quote
Dave_G
Quote
akstraw
By the way, the convertible battery is under the hood. Not sure why BMW put them in the trunk for other models.
Usually it's done for F/R weight distribution -- I can only assume that BMW did it in the E30 for the same reason.

I forgot that the iC has the battery in the front. The iC is about 150-250 pounds heavier than other models, so I guess the weight distribution is different enough that it made more sense to put it up front.

Part of the reason for moving the battery to the rear may have been weight distribution but it also had to do with battery longevity.
The under hood temperatures can get pretty high in stop and go traffic since the battery is mounted just above the exhaust manifold. Heat deteriorates batteries much more quickly than cold.
January 07, 2009 11:35PM
There is also some law in Germany that a device like a battery that emits flammable gas (hydrogen) is a fire hazard and is not allowed in the engine compartment. All the old beetle VW had the battery under the rear seat. The seat springs could sag and short out the battery terminals, setting the car on fire. Sort of typical of government actions and unintended consequences. At least that is what I was told by someone about the location of batteries on German cars.

Bob in Everett
January 20, 2009 01:32PM
I really like the carquest European 48-72. It fits perfect and seems to last a long time. It costs a few more bucks than the auto zone specials, but I think it is a better battery. To me there is nothing worse than looking at an older BMW to buy and in the battery compartment is some misfit piece of crap that was rigged to fit. That tells me that the PO was not into caring for or about his car!
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