Why does my lithium battery app's state of charge read differently to the Smart Battery Monitor app?
This information is applicable to the following products:
- Smart Battery Monitor (BSEN500)
WHAT CAUSES THE DIFFERENCE IN STATE OF CHARGE (SOC) READINGS BETWEEN MY LITHIUM BATTERY APP AND THE SMART BATTERY MONITOR?
Differences arise due to variations in calibration, measurement methods, battery aging, temperature effects, firmware/software updates and configuration settings. The Smart Battery Monitor units are 100% calibrated and tested in the factory and utilise industry leading measurement hardware to ensure accurate measurements under any conditions.
WHICH METHOD IS MORE ACCURATE? THE LITHIUM BATTERY APP OR THE SMART BATTERY MONITOR?
The Smart Battery Monitor uses a method called coulomb counting to achieve the most accurate SOC estimate possible, the typical error is within the range of 1-5%. In contrast, built in monitoring used by lithium battery apps may use other techniques such as voltage-based estimates and typically have errors in the range of 5-15%.
WHY IS THE SMART BATTERY MONITOR GENERALLY MORE ACCURATE?
The BSEN500 uses dedicated measurement hardware and smart software to compensate for all environmental conditions and ensure that measurements are always precise. They use a dedicated high current shunt to have accurate current readings over the full specified current range and use advanced filtering techniques to remove any errors due to electrical noise. In contrast the lithium battery apps use the internal BMS for measurements that may be affected by variations in ambient temperature or due to heating of the battery under high load conditions, leading to lower accuracy in measurements.
HOW DOES TEMPERATURE AFFECT SOC ACCURACY?
Temperature variations can impact SOC readings. The Smart Battery Monitor uses the built-in temperature sensor which can compensate for these changes, whereas the lithium battery app may not adjust as effectively if it relies on less precise internal measurements.
CAN SOC ACCURACY DEGRADE OVER TIME?
Yes, accuracy can degrade over time due to battery aging, sensor drift, or accumulated errors. The Smart Battery Monitor typically handles these factors better with regular recalibration (relearns what 100% is after every full cycle), whereas lithium battery app-based readings might become less reliable without recalibration.
HOW DO CALIBRATION DIFFERENCES AFFECT SOC READINGS?
The lithium battery app's internal BMS is pre-calibrated for typical battery behaviour, which may not reflect specific conditions or aging of the battery. In contrast, the Smart Battery Monitor is calibrated to your battery's specific characteristics, improving accuracy.
SHOULD I TRUST THE LITHIUM BATTERY APP OR THE SMART BATTERY MONITOR FOR SOC READINGS?
For critical applications where accuracy is essential, it is usually better to rely on the Smart Battery Monitor due to its higher precision and better calibration.