Battery Water Level Indicator


Instantly know if your battery needs water!


  • Dual Spark Arrestors
  • Water Miser™ Technology
    Reduces Evaporation
  • No Electronic Sensor to Fail
  • No Valves to Malfunction
  • Acid Proof

See below for ordering instructions

To buy, first select an item in the drop down box by clicking on the “▼” below. Then enter the quantity, then click the “Add to cart” button, then click the “Checkout” button on the left.

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Testimonial- “They are perfect so far, our guys sure do like them!” – Don (Maintenance Supervisor – Texas USA)
Our battery water level indicator made their chore of checking electrolyte levels much easier. They liked them so much, they recently ordered 200 more. They installed the water level indicators on backup battery arrays in their oil refinery to ensure that correct water levels are maintained.


  • Easy to use and see.

A mechanical float with a red tip is easy to see on the vertical sight glass.

  • Patented Technology

The VMV with Water Miser™ technology will reduce the water loss in the battery cell.

  • Easy Installation

Bayonet 1/4 turn installation will ensure correct fit into the cell.

  • Safety

The flame arrestors will prevent any external spark from entering the cell.

A large problem with battery maintenance is to know when to fill batteries with water. Without indication, operators often need to devise watering schedules or carry out periodic inspections to maintain the batteries. With our Battery Water Level indicator, the guess work of when to water is gone. No schedules are needed and less time is wasted. The red and green indicator ensures that mistakes are not made by operators so that your batteries are always properly watered.

Several models are currently available to accommodate various water level heights in different batteries. The chart shown below is for general reference only, and should not be relied on to determine which water level indicator will fit your battery. Please measure your battery before ordering by following the instructions below.

Battery Water Level Indicator Chart
Fill HeightMount TypeIndicator Model #
Group L161.39"Bayonet4000425
Rolls Surrette
Series 4000
Rolls Surrette
Series 5000
Enersys Varta2.62"Threaded4000600 with
M27X3-SIA adapter

Click here to view the M27X3-SIA threaded adapter webpage.

Click here to view the adapter drawing.

Please measure your battery before ordering by following these steps. Remember to wear protective clothing, gloves and goggles. 1) Make sure the water level in the battery is full per the battery manufacturers recommended fill level. For most lead-acid batteries, the water fill level is 1/4″ below the bottom edge of the battery vent well. 2) Measure the distance between the electrolyte and the top surface of the battery where the vent cap sits on. Then locate the model number in the chart above that corresponds to the water fill level dimension of your battery.

You may view the part drawing that shows the dimensions for each water level indicator model by clicking on the links below:
Battery Water Level Indicator #4000425
Battery Water Level Indicator #4000550
Battery Water Level Indicator #4000600
Battery Water Level Indicator #4000600 (with M27X3-SIA threaded adapter)

Electronic water level monitors are susceptible to failure due to battery acid and the harsh environments that are usually associated with batteries. Our water level sensor is a mechanical float made of polypropylene which is not affected by battery acid.

Valves in single point watering systems fail. You simply cannot rely on gadgetry when the life of your batteries is at stake.

Fast, accurate visual inspection of a mechanical water level gauge is the only foolproof way of knowing when you need to add water to your battery.

How it works:

To indicate when the battery water level is full, the float raises the indicator mark to the “MAX” water level line  (see Fig. 1). As the water inside the battery evaporates, the float lowers the indicator mark in the sight glass. As long as the indicator mark is within the green area (see Fig. 1), you do not need to add water.

When the indicator mark is in the yellow area (see Fig. 1), this indicates you should add distilled water to the battery. If the level indicator mark is in the red area, there is still some water left inside the battery, but the battery should be watered immediately since low water levels can damage the battery.

If the level indicator mark falls below the “MIN” line (see Fig. 1), eventually the plates in the battery will dry out and permanent damage to the battery will occur.

Note- always use distilled water. Never add sulfuric acid to a battery. Normally a battery loses only water since sulfuric acid does not evaporate.

Custom float lengths are available to fit the water levels of most batteries. Call for details.

Made in USA at our factory in Ohio. Dealer inquiries are welcome. Quantity discounts are available for 100 or more. Please contact us for pricing.

Click here to view the Battery Water Level Indicator brochure.

Additional information

Weight.05 lbs
Dimensions5.5 × 1.63 × 1.63 in
Model #

4000425 (1.39" Fill level), 4000550 (2.50" Fill level), 4000600 (3.10 Fill level)