I’m running a robot driven by a VNH5019 dual motor driver, two 25D gearmotors, and a 7.2V NiMH battery pack. My microcontroller and sensors share this same battery rail via a 5V buck regulator.
Under sudden acceleration or single-motor pivot turns, my BNO085 IMU would lock up and stop sending data (likely due to voltage dips from motor current spikes). To fix this, I soldered a 2200 µF electrolytic capacitor directly into the motor driver’s auxiliary capacitor holes.
I wanted to double-check: is adding a capacitor of this size directly to the driver board a reliable long-term solution for this setup, or are there any drawbacks I should keep in mind?
A 2200 uF capacitor in the provided holes is generally acceptable if its polarity and voltage rating are correct. However, it only reduces supply dips and is not a complete fix for motor noise.
Also add 0.1 uF ceramic capacitors across the motor terminals, keep motor wiring short and twisted, separate it from the IMU wiring, and place local decoupling near the buck converter and BNO085. Check the battery voltage with an oscilloscope if possible; persistent dips may indicate that the battery or wiring cannot handle the motor’s stall current.
This overview of bulk, decoupling and bypass capacitors also explains why the 2200 uF capacitor helps with slower voltage dips but should be complemented by small ceramic capacitors for high-frequency motor noise.
