Older Prius battery module internal resistance

I’ve been working on repairing the aging NiMH battery modules in my 2004 and 2012 Prius. Some cells had started failing, so I began the replacement process, slowly swapping out modules one by one.

However, I quickly realized this approach was inefficient. Simply checking module voltage isn’t the most reliable way to determine battery health. While you can easily find used Prius battery modules on eBay or through local sellers, most only list the battery voltage—often measured right after charging—as proof of a “good” module. Unfortunately, this isn’t always accurate, and many times you discover the module doesn’t actually perform as expected once installed.

A much better method is to measure both the module’s voltage and its internal resistance. Internal resistance is a strong indicator of battery health—low resistance cells are more efficient, less lossy, and deliver more consistent performance.

As an electronics enthusiast, I built a simple meter that measures internal resistance. It runs on a basic 9V battery, is cost-effective, and makes it much easier to evaluate the true condition of hybrid battery modules. We’ve even launched a Kick-starter to make this tool accessible to anyone who wants to test, repair, or optimize their own hybrid battery packs.

https://www.kickstarter.com/projects/1842571016/hybrid-battery-module-internal-resistance-meter

sending this in hope this is helps someone like me to get battery in shape back.
Thanks
Nitin