Battery Overflow Question
 

I have the original battery on my '03 Boxster S. The other day I was filling with distilled water and apparently put too much in and it overflowed. The overflow plumbing on the right side of the battery functioned properly. However there seems to be an overflow hole on the left side of the battery as well. The left side has no overflow plumbing. Should there be a hose connected to the left side like there is on the right side?

Hi,

No, there is only one vent tube - it is not an overflow tube. The other side is usually stopped by a plug.

The tube's purpose is to vent Hydrogen Gas that the battery naturally emits to prevent it from becoming trapped under the hood where it could pose a problem if an ignition source were introduced (unlike the airflow present around batteries on most front underhood locations which will not allow it to accumulate). If you overfilled the battery, this tube could well become filled with the excess electrolyte, but that's not it's purpose.

The Tube extends below the car and draws off any Hydrogen Gas via bernoullie action of the airflow past the tube opening. Hope this helps...

Happy Motoring!... Jim'99

Not really your guestion, but the battery tray has 2 drain holes. You cannot see the second hole because the battery is blocking the view.

Thanks, Jim for the excellent explanation. Incidentally, what is the proper level of fill for the battery?

Norm

Hi,

Each Battery is different. Some have Fill marks raised on the side while others use the Fill Holes or Lip themselves as the Fill Gauge (this is what the OEM battery uses). It should state this somewhere on the battery itself, or in it's documentation.

In any event, you want to completely cover the Plates or Grids in the Battery. Too much water is not advised because you over-dilute the Electrolyte which will reduce the Battery's chemical reaction and thereby it's ability to produce free electrons which is the power the car uses. It will also slow the reaction time as well. Combined, these will weaken the Battery and it's regenerative chemistry. Hope this helps...

Happy Motoring!... Jim'99