Not really Maintenance Free
 

Since today was relatively warm (upper 40) I decided to check out the battery on my X. During the past cold spell I had to hookup a maintainer to charge the battery. If the car sat out over night, by morning when I connected my maintainer to the engine jump terminal in the engine compartment, the maintainer would tell me that the battery was at 60 to 70% capacity. Some time it dip below 60% capacity. After charging the battery (usually for an hour) it would register 100% on the maintainer's display. My battery is not the original battery and it had caps on top. I removed all the caps and with the battery water fill tool that use to belong to my dad I filled all the cells up with distill water. It took a little less than half a gallon to fill all the cells. Hope this fix my low capacity problem. The car never fail to start, but one time my airbag came on (the coldest morning of the week 5F), but it went off the next time I went to restart the engine. Maintenance Free batteries are not always maintenance free.

show us pics of the tool.

My dad was a mechanic and my brother and I got all his tools. These use to be at every gas station when they were full service station.

http://i.ebayimg.com/t/BATTERY-FILL-...qfg~~60_58.JPG

They are still available on Amazon or eBay. The nice thing is that they stop filling the cell once the proper water level has been reached.

That's pretty cool. I would get it, but it looks like it is big. And I already have a ton of tools.

The X needs a battery that vents thru a tube to the outside, if your battery has removable caps it is venting into the enclosed battery/spare tire/electronics compartment. Best case you will have corrosion in that area, worst case will be a major explosion due to battery fumes igniting from any spark at all (static included).

It has the side vent and the tube was attached to the vent for the battery. The caps had two o-rings on them to prevent gas from escaping into the trunk.

I think he meant that there were removable caps/lids over the battery's cells...that allow you to check the fluid level. These batteries still get vented. :)

The original BMW battery was like that on my e38...look closely at the images below...you can see small round removable caps down the center with a "+" indentation for inserting a screwdriver to facilitate removal. And there's also the vent hole on the side that connects to the car's gray vent tube (these pics are from somewhere around 2003/2004):

Ahhh...that's a cool little tool. :)

Since most of us don't have a perspective of it's size...placing something that is familiar to everyone...like a coin...would give immediate perspective of its size. :)

My bad. I assumed the battery did not have the required vent tube. There was a member here who had a battery compartment explosion last year, think he was posting from Russia.

Im surprised many here somewhat new to this thing, they have been around for ages, and most of us are pretty mechanically inclined! They can be had in many sizes..but are normally only a couple quarts for automotive batteries.