What you need to know about electrolyte leaks

The heart of a hybrid EV system is its battery, which which stores the energy that powers the electric motor. As with any complex system, there are risks associated with the use of hybrid electric vehicles. One of the most significant dangers is the potential for electrolyte leaks in hybrid EV batteries that use nickel-metal-hydride (NiMH) chemistry.


What is an Electrolyte?

Electrolyte is a substance that conducts electricity when dissolved in water or other polar solvents. It is a key component of most batteries, including NiMH batteries, which are commonly used in hybrid EVs. The electrolyte in a NiMH battery is typically a mixture of potassium hydroxide and water. When the battery is charged or discharged, ions in the electrolyte move between the electrodes, allowing the battery to store and release energy.


Not a Dangerous Good

While NiMH batteries are generally considered safe, there is a risk of electrolyte leaks, which can have serious consequences. If the battery casing is damaged or the seals are compromised, electrolyte can leak out of the battery and come into contact with other components of the vehicle. This can cause a range of problems, including:

  1. Corrosion: The electrolyte in NiMH batteries is highly corrosive and can cause damage to the vehicle's electrical system, particularly if it comes into contact with metal components.

  2. Fire: If the leaked electrolyte comes into contact with a spark or other ignition source, it can ignite and cause a fire. This can be particularly dangerous if the battery is located in the passenger compartment of the vehicle.

  3. Toxicity: The potassium hydroxide in the electrolyte can be harmful if it comes into contact with skin or eyes. It can also produce toxic fumes if it is exposed to heat or fire.


We see a lot of batteries at Infinitev, including those that have been rebuilt without regard of what we'd call best practice guidelines or minimum quality standards. The result, at times electrolyte leaks exposing customers to potential dangers as outlined above. 

Here are some examples of what we received this week. Thankfully our team are always on guard for potential dangers and managed the electrolyte safely. The modules and impacted parts have been responsibly managed by our end-of-life partners. 

Electrolyte leak on hybrid modules

Electrolyte leak on prismatic NiMH modules


Electrolyte leaking through the battery case

Electrolyte leaking through the battery case



To mitigate these risks, it is important to take proper precautions when handling NiMH batteries. This includes ensuring that the battery casing is intact and the seals are in good condition. If a battery is damaged or leaking, it should be replaced immediately. It is also important to handle the electrolyte with care and to dispose of it properly, as it can be harmful to the environment.

In addition, it is important for vehicle manufacturers to design battery systems that minimize the risk of electrolyte leaks. This can be done by using high-quality materials for the battery casing and seals and by incorporating safety features such as sensors that can detect leaks and shut down the battery system.


Questions or Concerns?

We've probably seen it all before, so if you have any questions or concerns whatsoever, give us a call. Our engineers and battery experts are here to help. Free call 1300 360 111 (AU) | 0800 360 111 (NZ).