EVs and EV Chargers must be watertight. What is your team doing to make sure?

One downside to electric vehicles is that they can be vulnerable to water damage. If the car gets wet, it can short-circuit and stop working. This is a significant problem because electric vehicles are becoming increasingly popular. If people buy these cars and can't use them because of water damage, they will be depressed.

Electric vehicle manufacturers go to great lengths to ensure their products are watertight. They often use seals and gaskets in critical areas and special coatings that help keep water out. In addition, some manufacturers test their products in extreme conditions to make sure they can withstand the elements.

When designing fasteners or clips that need to be watertight, here are your options.

1. O-ring – Some teams complain about O-rings falling off in transit or during repair, so ensure that the 0-ring is encapsulated or fixed on the fastener.
2. Liquid Seals – Most of these are applied by a vendor, but many need something to activate their curing process. Ensure you understand the seal requirements and that your application will live up to those requirements.
3. Rubber Seals – These often look like a 0-ring, but they are mechanically applied to the fastener and don’t fall off. They sometimes bead up or spit off some of the rubber, so make sure you work with a good supplier for that seal.
4. Major Sealant Brands:
   1. Plastisol – If you want a widely available and cheap seal, this is your best bet after an O-ring. It’s not safe to put in an oven and may fail due to environmental issues, but it’s the most used in any industry for a quick-fix seal.
   2. Silicone – Often used on anything electronic, from battery applications to the two screws in the bottom of your iPhone. There are not many vendors that specialize in it, and it’s expensive, but depending on your application, it may be your only option.
      1. While silicone often looks like a glazed donut under the head of your fastener, some battery suppliers also use a dipped coating encapsulating the entire head of the fastener by a company called Three Bond.
   3. Oven Safe – Many EV parts and closures go through an E-bake process or painting that hardens in an oven. The oven is 350F for 30-45 minutes, so your sealant must survive the cook.  
      1. Rimlex® is a sealant out of Europe with two options for high heat applications
      2. Nyseal® is a new product from Nylok that many OEMs are trying on their products.
      3. Sealtech is from ND Industries, and it’s what we are trialing for several battery box applications.
      4. The pics below from Avdel’s Monobolt® Rivet and Termax’s Heartflex clip are good examples of how to look for a potential leak path.

Do you know what watertight means?

It’s essential to understand your watertight needs, from the seal requirements to the application requirements. Most companies use two tests; 67 below is a dunk test or submerging your part to test for air bubbles. The other test is a rain test for a box trailer company to make sure they can stay dry on the inside during a rainstorm.

One of the biggest mistakes made by designers is assuming a seal solves all your needs. A seal only works if the application is correct. From Hole diameter to angles on the joint, a sealed fastener on the print is not a guarantee of a watertight joint in your production environment.

Testing is crucial during your design and prototype stages. Many EV efforts are not testing the watertight joints enough or at all, and if they have a leak in the field, it’ll be a recall nightmare. We work with https://lacotech.com/ to ensure our client’s, battery to EV mfg., have the seal testing method they need to ensure a rainproof, watertight, or helium-tight application. You can test items on the line or in a lab, but make sure you test your assumptions.

Reach out if you are having sealant issues or applications that need to be reviewed. Super Charger Photo Credit, tiremeetsroad.com