Battery Water Level Indicator


Instantly know if your battery needs water!


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

See below for ordering instructions

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Testimonial- “They are perfect so far, our guys sure do like them!” – Don (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.


  • 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 the Visual Monitoring Vent (VMV) device, 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.

Several models are currently available to accommodate various fill level heights in different batteries. The chart shown below is for general reference only, and should not be relied on to determine which 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

The M27X3-SIA threaded adapter is available here.

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 fluid level in the battery is full per the battery manufacturers recommended fill level. For most lead-acid batteries, the fill level is 1/4″ below the bottom edge of the vent well. 2) Measure the distance between the fluid 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 fill level dimension of your battery.

You may view the part drawing that shows the dimensions for each 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 level monitors are susceptible to failure due to battery acid and the harsh environments that are usually associated with batteries.

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

Fast, accurate manual inspection is the only foolproof way of knowing when you need to add water to your battery.

How it works:

When a battery is full, the mechanical float raises the indicator mark to the “MAX” 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), that means you should add distilled water to the battery. If the indicator mark is in the red area, there is still some water in the battery, but it is urgent to immediately add water.

If the 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 (sulfuric acid does not evaporate).

Custom float lengths are available to fit 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 product 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)