A basic battery question....
 

Once in a while in the winter I put the battery charger on my Boxster battery. The kind of battery is a Canadian Tire product about 3 years old. It has the screw caps(6) on top presumably to put distilled water in.

The question is this - should the screw tops be removed while I am charging the battery? Perhaps the caps are vented anyway. How does it work with sealed batteries - are they vented?

Unless you are really cranking a lot of amps to it for a quick charge you should be fine without removing the caps. Any trickle charger will be fine.

Not knowing the charging rate, it depends. If a cell is faulty, it might overheat even at a relatively low charge rate. Remove the vent caps and monitor the electrolyte level in each cell just to be safe.

Yes. "Sealed" batteries are internally vented.

Sherwood