Battery acid "odor" in trunk? Feedback on Optima battery? - The Unofficial BMW M5 Messageboard (m5board.com)

mottati · 6th August 2004, 07:45

Since buying my 00 M5 a year ago, i've noticed a smell in my trunk that i attribute to my battery. It kinda smells like battery acid. It's noticable after a long, hard drive, especially if it's hot. The battery was replaced by the selling dealer as part of the cpo process (interestingly, it was still wrapped in plastic and the vent not hooked up when I took delivery of the car!). The vent is connected, and not blocked. I also have a little "discharge" around the vent tube. Is this normal? (i mentioned it once when the car was in, thinking that maybe it was being overcharged and boiling off the fluid, dealer says charging system is ok, and i've checked the fluid numerous times, it's stable.)
I'm thinking of ditching the bmw battery and trying an Optima, anyone go that route? Which one did you use? Other than top color, do they have different sizes?
THanks...
Mike

BKH · 6th August 2004, 07:54

In my M3 an Optima orange-top was a drop-in fit, dead perfect. I contacted Optima to see if one would fit in the M5 but they said no, so I replaced my OE battery with one from the dealer. There seem to be a number of other interesting batteries out there also so I wouldn't give up yet on the idea of a sealed aftermarket battery, since it's not a matter of immediate need.

Ike · 6th August 2004, 08:12

I had an optima battery in my Miata's trunk for over a year with no problems at all. I plan on putting one in the Mercedes when it needs a battery too.

I really don't like the idea of having a normal battery in the trunks of my cars.

The one I used in the Miata is the smallest red top but it has higher cranking amps than stock, it solved the slow starting problems caused by the tiny wires that run to the batt. in the trunk.

Here are links to their specs
http://www.optimabatteries.com/produ.../technical.asp

marinakorp · 6th August 2004, 16:49

check to see if the exhaust tube is connected to the battery...

my understanding is that the douglass battery (OEM - US) has a exhaust tube to prevent boil overs, etc... might want to check

1 - condition of battery... make sure in good condition
2 - the vent tube is connected

M5Kid · 6th August 2004, 19:05

It is my understanding that there are some good aftermarket batteries out there that are also lightweight and would provide a good weight savings. That along with your catback Supersprint system would definetly shed some pounds.

Travis

mottati · 6th August 2004, 19:21

Quote:

Originally Posted by marinakorp

check to see if the exhaust tube is connected to the battery...

my understanding is that the douglass battery (OEM - US) has a exhaust tube to prevent boil overs, etc... might want to check

1 - condition of battery... make sure in good condition
2 - the vent tube is connected

Yes, the vent is connected and 'patent', i can blow air thru it. The battery is about a year old, and is a bmw replacement battery.

And yes Travis, I wouldn't mind loosing a few more lbs with a lighter battery. I see these guys on the m3 boards running these ridiculously small dry cell batteries, they look like what you'd use for a lawn tractor or something. I'm not that extreme... but i noticed the optimas at my local auto zone the other day and it got me thinking. It felt quite a bit lighter. I'll measure the battery box and see what kind of dimensions we've got.
Thanks Guys,
Mike

baf3472 · 6th August 2004, 19:42

You can save yourself some money and buy a douglas battery for about 120. Thats what i had done on my 528. Douglas makes the batteries for BMW so it would be a direct fit.

mottati · 6th August 2004, 19:54

Quote:

Originally Posted by baf3472

You can save yourself some money and buy a douglas battery for about 120. Thats what i had done on my 528. Douglas makes the batteries for BMW so it would be a direct fit.

Actually, the optima's i've seen cost that much or less. My battery is ok (as far as i know) but i'd like to go with one of the non-fluid filled batteries, and maybe loose a little weight.
mike