PZEM-015 Battery Monitor - Capacity Ah left in battery

[ArranP]

I recall when back when I bough a Lithium battery that it came with one of these PZEM-015 battery monitors, if my memory serves me right the "Capacity Ah" went up when charging and down when dis-charging thus giving an indication of the number of Ah left in the battery.



The battery monitor failed and I purchased a replacement PZEM-015, however now the "Capacity Ah" only goes up both when charging and dis-charging, I've checked the shunt size and the setting is correct.

Am I missing something ? What is the experience of others or if not this meter what meter is used to keep a track of the number of Ah that are left in the battery ?

Thank you for feedback.

Regards
Arran.

 

[RCinFLA]

Battery monitor with Columb counter has to measure positive and negative current accurately.

A common issue with cheap monitors is DC offset for current shunt op amp. If zero current point is skewed off to one side, it causes polarity sense of current to be incorrect at low current levels. The Columb counter just continues to build the small errors versus time.

Check if monitor measures zero when there is zero current flowing through it. It may not show enough digits of resolution to ensure there is insignificant DC offset.

A quality meter has automatic DC offset correction.

 

[ArranP]

Does anyone know of a Columb counter preferably with wifi that can reset to 100% at a set pack or cell voltage ?

The problem being columb counters drift upwards due to the bms doing its active balancing of cells.