Measure internal resistance (IR) using your battery charger
Internal Resistance as a Battery Health Indicator
Internal resistance is a key indicator of battery health, reflecting the opposition to current flow within the battery. Increased internal resistance typically signals aging or degradation, affecting performance and efficiency. By monitoring this metric, we gain precise insights into battery condition and can better predict potential failures.
IMPORTANT
A. Your battery must be slightly discharged when you put it on the charger, because the charger will need 1-2 minutes of charging in order to measure the resistance
B. Take resistance readings AT FULL CHARGE (25.2V), before you remove it from the charger
*If you remove the battery from the charger before taking the resistance reading, you will have to discharge the battery and charge it back to full in order to get the proper IR measurement
How to Measure IR Using the 2-Port D6 Charger
You should regularly check the internal resistance of your batteries, you can do this using your charger.
- Use the "Charge" mode to charge your batteries (this mode still balances your batteries. You can use this mode instead of "Balance")
- After a 1-2 minutes, you will be able to use the scroll wheel to view the second information screen, here you will see the IR of each cell, at the present charge level
- Wait for the battery to complete charging, then read the IR values
Tracking Internal Resistance
It is wise to track your internal resistance so you can begin to correlate IR values to battery behavior, and better understand when to disqualify a battery.
It is also good to pair your batteries based on their IR values and other characteristics. When you use a battery with higher IR with one that has lower IR, you can experience lower efficiency or other issues.
Mark your battery pairs so you can ensure you use similar batteries for each flight. Use masking tape or labels to write dates and IR values on each battery, so you can track degradation, and avoid using bad batteries.
Bad Internal Resistance Values*
*IR values will vary with different measurement devices
If your IR values look like this when measured on the 2-port D6 charger, your battery is nearing the end of its life, and you should consider removing it from rotation. If your battery shows any other signs listed in this article, you definitely need to stop using it: Battery Disqualification
Total IR above 27mΩ
Highest cell IR minus lowest cell IR is above 2.5mΩ