Water Miser Battery Caps

Fits all U.S. Manufactured batteries except the (so-called) "maintenance free" type. Water Miser, Flip Top Battery Vent Cap, 1 1/8" bottom insert width, total width 1 3/8" x 1/4" height into battery insert and 1" height above the battery insert

Water Misers are molded plastic "flip-top" vent caps designed to reduce and ease maintenance on flooded Lead-Acid batteries.

There is no need to remove the caps when charging, filling, or equalizing the batteries. When charging, the plastic pellets capture up to 90% of the moisture and acid droplets. This reduces acid fumes, corrosion, and keeping the battery tops much cleaner and dryer. Excess water is dropped back into the battery cell.

Water loss is reduced, which extends time between watering. Note - These are not the same as Hydrocaps. There are advantages and disadvantages to each:

Differences between Hydrocaps and Water Miser caps:

1. Hydrocaps should be removed when equalizing, or they can get extremely hot and may be ruined. Water Misers can stay in place all the time.
2. Hydrocaps re-combine the Oxygen and Hydrogen released by the battery while charging, reducing water loss up to 90%. Water Misers do not re-combine, but water loss is reduced by 50-80% by trapping fine water and acid particles. They also take up a lot less space above the battery. Since Hydrocaps must be removed when the batteries are being heavily charged you do not get the full benefit of recombining.
3. Hydrocaps are more expensive - because they do more. Hydrocaps will not last forever, though - life will vary from 3 years to 8 years, depending on charge rates and how they are treated. If left on during battery equalization, they can be quickly used up and/or ruined.

We do not really recommend Hydrocaps for small systems, such as RV's. They work fine, but they are a bit expensive, and they sit up rather high on the battery and are prone to damage. They are really meant for fixed installations.