Working voltage, resting voltage, and the 50 percent rule

My cheap china Ah meter is almost useless in that you have to frequently reset the 100% value. Certainly the Victron, Bogart and Magnums are better especially when used in conjunction with their chargers.

But I primarily follow BFL and other's morning Voltage check.

EDIT: Heard elsewhere from someone who believed his Ah meter rather than "resting" voltage and undercharged his batteries for months, Until he discovered the Ah meter calibration was off. Luckily his batts were LiFePO4.