to vent the Hydrogen gas that is produced when the battery is being charged.
Ventilation. Auto batteries out-gas hydrogen under certain circumstances, and it must have a way to escape the battery case. "Holes in the caps" would be an older style battery. Today, most batteries have a flat, narrow tube along the top that fufills that function.
charge batteries with caps in place.most U.S.A batteries are made with flame.
All lead acid batteries are always charged with the caps on. What this prevents is the acid accidentally boiling up an out of the cell and doing damage to surrounding equipment. When a car battery in a vehicle is charging when the engine is turning over, the caps remain on. This procedure should be no difference when the battery is on a plug in battery charger, the caps remain on. There are vent holes in the caps which allow any built up pressures to release.
If the battery has caps and is not sealed check the level of the electrolyte. If it is low add only distilled water.
Car batteries are rechargeable storage batteries. They are designed to be constantly recharged.
car batteries
DC definitely, all car batteries - all batteries.
BJ'S sells Excide car batteries.
a car battery that can be recharged. All automobile batteries are rechargeable.
You should check the battery water every few months. Take off the battery caps -- usually there are two of these caps with three cells below each. (You may need to slip a screwdriver blade under the edge to break them loose and get the removal started). Look into the holes. You will see some narrowing shelves about an inch or so down in the holes. Water should be level with the holes in these shelves. If not, add distilled water to bring the levels up to the shelf holes. Wash your hands after removing and replacing the caps, because they may have battery acid on them.
dc
Car batteries are almost as unique as any other part. No they are not universal.