[Josh (PA)]

I got in a slightly heated debate with my father last night over automobile batteries, and BMW batteries in general. He was emphatic that you need to regularly check the "water level" of our battery. He was pissed because he opened his up the other day and "had to" add a good deal of water to his battery. He was pissed at our dealership for not checking it....

Now I've worked in the battery iindustry for a few years, specifically on VRLA Lead Acid cells, and catalysts for them, and am more aware of how AGM cells work than most, so this poll is more for me to get an idea of people's beliefs on this subject.

FYI, anyone that wants to know why not to add water to valve regulated cells can go here:
VRLA cells 101

 

[Nick325xiT 5spd]

There's a sheet with my manuals and such suggesting that the warranty on the car is void if I don't check the water religiously and get the sheet filled out. I can't honestly say that I have, though.

 

[Kaz]

This depends on whether the battery is one that even has water in it. There are lots of sealed types out there these days (thought usually not used in cars from the factory) that dont use water, such as gel, spiralcells, and I believe AGM.

But if its one that has the traditional 'wet' construction and if there's any way to get in there to add water, I do it.

 

[dredmo]

This depends on whether the battery is one that even has water in it. There are lots of sealed types out there these days (thought usually not used in cars from the factory) that dont use water, such as gel, spiralcells, and I believe AGM.

But if its one that has the traditional 'wet' construction and if there's any way to get in there to add water, I do it.

yup, i maintain power plants for part of my job, and on any wet cell battery, water needs to be regularly checked. Especially, on a wet cell battery, where one cell is performing all the work. Most consumer batteries these days are not wet cell, or another term flooded cell. So most people do not realize that we still have wet cells in some of our cars. Usually there will be a water level line. When a battery discharges, the electrolyte level will change. Water in fact becomes the electrolyte when added, it will evaporate over time, but the acid will stay in the battery for the most part.

So it is important to keep a maintained water level in your battery.

Now on a side note, I have never had a battery that needed water. I am in a bad habit of never even checking them anymore. I couldnt even tell you what kind of battery is in my BMW. As important as it is, they just never go bad frequently enough to get out and check the battery every week, and they are very expendable, so most people are to lazy to maintain it.

 

[WAM]

Do we have AGM (Absorbed Glass Mat) batteries in BMW's? I must confess I haven't looked at mine since I couldn't figure out how to get to it easily.

I did RTFM but it seemed like I wouuld have to rip out trunk lining clips.

 

[Pinecone]

A couple of things.

It is well known the the Z3 community (or maybe it is known and should be well known) that the stock battery does need to be checked for water and people have had trouble becuase of low levels. The problem is, the stock Z3 battery has a sticker covering the cell tops and it LOOKS like a sealed battery. But it isn't.

As for my other car, see elsewhere my report on the battery going screwy.

Oh, and a bunch of years ago my wife blew up the battery in her car. Literally it exploded. She never checked the water and the level got low enough that there was some arcing of the plates, and it ignited the hydrogen gas produced during charging.