If you suspect your Assist or Assist PLUS Electronics Box is allowing water inside, a fresh-water dunk test can help determine whether the box is leaking and, in some cases, identify where the water is entering.

This is a practical troubleshooting test that can be used alongside a visual inspection of the Electronics Box, including checking the lid, latches, seals, hinges and other components for damage.

Important: Always perform the initial dunk test without the battery installed. The battery should only be installed for the second stage of the test if required.

For instructional video, see: Fresh Water Dunk Test Guide

What Is a Fresh-Water Dunk Test?

The dunk test involves placing the closed Electronics Box into a container of fresh water and applying gentle pressure to different areas of the box.

The test can help identify:

• Whether the Electronics Box is allowing water inside.
• Whether air bubbles escape from a potential leak point.
• Whether movement or pressure on the box causes water to enter.
• Whether the cable or lid area may be contributing to the leak.

Do not perform this test in salt water. Use clean, fresh water only.

Step 1 – Test Without the Battery

Before starting:

1. Remove the battery from the Electronics Box.
2. Perform your normal visual inspection.
3. Check the lid, latches, seals, hinges and cable entry points for obvious damage or issues.
4. Close the Electronics Box normally and make sure the lid is properly secured.

Dunk the Electronics Box

1. Place the closed Electronics Box into a container of fresh water.
2. Give the box a gentle shake while it is underwater.

This helps remove any air bubbles trapped against the outside of the box. Trapped air bubbles can otherwise be mistaken for bubbles escaping from a leak.

3. Gradually submerge the box deeper into the water.

The deeper the box is submerged, the greater the water pressure acting on the Electronics Box.

4. Look closely at the box for any bubbles escaping from a particular location.
5. Gently move or wiggle the cable while observing the box.
6. Apply firm, even pressure to different areas of the Electronics Box.
7. Test the box in different orientations and check for bubbles or signs of water entering.

Why Look for Bubbles?

If air escapes from inside the Electronics Box, this can indicate a potential leak path.

As you apply pressure to the box, look carefully for a continuous stream of bubbles from a specific location.

This can help identify where water may be entering the box.

Check the Electronics Box

Once you have completed the test:

1. Remove the Electronics Box from the water.
2. Dry the outside of the box thoroughly before opening it.
3. Open the box and inspect the inside for any water or moisture.

Do not assume the box is leaking simply because you see bubbles on the outside. Make sure you have dried the box and confirmed whether water has actually entered the Electronics Box.

If Water Is Found Inside

If water has entered the box but you could not identify where it came from:

1. Dry the inside of the Electronics Box completely.
2. Close the box again.
3. Repeat the dunk test.
4. Carefully observe the box for bubbles and inspect the suspected areas.

Repeating the test can make a small or intermittent leak easier to identify.

Step 2 – Test With the Battery Installed

If the Electronics Box passes the initial test without the battery, you can repeat the test with the battery installed if you are troubleshooting water ingress that may be related to the battery or its installation.

Only install the battery once the Electronics Box and battery are completely dry.

1. Install the battery normally.
2. Complete your usual checks to make sure the battery is correctly seated.
3. Close and secure the lid.
4. Confirm that the latches are properly tensioned and remain securely closed.
5. Place the Electronics Box into fresh water.
6. Give the box a gentle shake to remove trapped air bubbles.
7. Gently wiggle the cable.
8. Apply firm, even pressure to different areas of the lid and Electronics Box.
9. Test the box in different orientations.
10. Watch carefully for bubbles escaping from any particular location.

Pay particular attention to the four corners of the lid, the latches, cable area and sealing surfaces.

After the Test

1. Remove the Electronics Box from the water.
2. Dry the outside of the box thoroughly before opening it.
3. Open the box and inspect the inside for water or moisture.

If there is no water inside the Electronics Box, the unit has passed this dunk test.

If Your Electronics Box Is Leaking

If water is found inside the Electronics Box, repeat the test after drying the box and carefully inspect the areas where bubbles were observed.

Also check for:

• Damaged or incorrectly seated seals.
• Damaged hinges.
• Bent or damaged latches.
• Damage to the lid or Electronics Box.
• Issues around the cable entry point.
• Debris or contamination preventing the lid from sealing correctly.
• Any other visible damage to the sealing surfaces.

If you cannot identify the source of the leak, contact the Foil Drive Support Team and provide details of your test, along with clear photos or video of any suspected leak point.