Determining Battery Voltage

Determining Battery Voltage

NOTES: Short term loads are defined by an expected "on" time "t(ON)" of less than 30 seconds at a current of more than 10 A.

The battery voltage is determined in a number of different ways. The current voltage is measured once and the measured value is filtered so that short-term voltage drops, e.g. when servo motors are switched on, do not render the value incorrect. A time based mean value is also determined (unweighted, mean value over a fixed time period) - this has very little effect on short-term loads. If a high-current load is switched on (e.g. status on the CAN bus) and if the current voltage value is lower than the determined value, the mean value is used to detect the vehicle electrical system status. Otherwise the current measured voltage value always has priority.