An interesting article warning you of some of the dangers of cheap knock off lipo chargers (of which the imax B6 clones are famous). But the great thing is the guide goes on to show you how to fix the shortcomings! - you can find the full article by Phillip Ryals here
Sometimes buying a low-cost clone off of eBay is a great option, but [Martin] wisely decided to test his counterfeit IMAX B6AC, and found it grossly lacking. His detailed breakdown shows an alarming array of problems, including poor design and construction, and a lack of warning if the balance circuit fails. In addition, the charger wasn’t properly calibrated. By using a precision multimeter, Martin found that the charger actually brought cells above critical voltage. So really, using a charger like this out of the box can both destroy your battery pack and/or start a fire. One other interesting detail – this model can only be calibrated once. Sweet features.
[Martin] detailed his fixes in a well-illustrated blog post. He first had to re-enable the calibration menu using this method which requires bricking the device first! Once un-bricked, however, he could do the recalibration using a voltage divider and a reliable power source.
This project really underscores the need for a precisely calibrated multimeter. Not only would [Martin] not have been able to test his charger properly, but the re-calibration wouldn’t have been as accurate as needed. As hobbyists, this is a reminder that we can only trust our tools if they are accurate.