Why can't we just replace the bad module?

Here's a question we get asked all the time: "why can't we just replace the bad module(s) with new ones?" The short answer: because we don't like to play whack-a-mole. 

Hybrid battery cell replacement is a game of whack a mole
Hybrid battery cell replacement is a game of whack a mole


How it works

To start we need to know how and why battery packs fail, which means we have to get a little bit technical. (Don't worry, we've tested this article on our non-engineering friends and no humans were harmed in the proof-reading of this blog post.) 

Hybrid batteries are made up cells that are connected to form modules, and those modules are connected to make a pack. With age and use how each individual module performs can start to differ slightly from the other modules. Weaker modules will start to discharge faster and take longer to charge than stronger ones. When this happens, the battery pack as a whole becomes unbalanced. 

In an unbalanced battery, the maximum charge that can be safely drawn cannot be more than the charge stored in the weakest module. The remaining energy in the other (healthy) modules is not available to power the vehicle and wasted as heat, which, as it turns out, is something that batteries don't like--it speeds up the degradation process further.

The short of it is, when a battery fails, it's not one big block that goes, but it's usually one or more of those modules that together make up the battery pack. Which then begs the question:

Why can't we just replace the bad module?

Module replacement involves replacing one or two weak modules with new ones. Sometimes, it will be enough to clear the warning lights on the dash and get you back on the road. But it's usually short lived (and we definitely do not recommend you start playing around with the high voltage system unless you are a licensed professional with all the right gear). 

The solution is short-lived because the rest of the modules, that are the same age and have the same wear and tear as the module that failed, remain in the battery pack. Unless you know how to select just the right module that matches the properties and performance of the remaining ones, you will end up with a pack that is unbalanced. 

And we know what happens to unbalanced packs: they fail. Module swapping becomes essentially a game of whack-a-mole…fixing one module now, and then another (and then another and another and another...). 

The benefits of rebuilding a battery 

TL;DR. Here's a video we shot on the topic instead. It's all about balancing the modules using sophisticated test equipment. 


Why choose Infinitev?

  • We're the hybrid and electric vehicle specialists.
  • Rebuilt replacement batteries offer outstanding value for money
  • Built in Australia or New Zealand at our ISO9001-certified facilities
  • Backed by our industry-leading 3-year warranty
  • Price includes shipping and fitment valued at $400-700 (no surprises)
  • Thousands of happy customers over the years
  • We collect your old battery and ensure it is recycled properly