HP 50g battery voltage: How accurately can it be measured?

[TravisE]

Interesting. I never really questioned the voltage reading in BatStatus because the reported values seemed fairly reasonable. I use it mainly to get a relative idea of battery level, but I ignore the state-of-charge percentage it gives and instead use my own formula to estimate SoC by reported voltage, based on actual previously-measured values during discharge of the particular cells I use. Although this varies widely by battery type, brand, usage conditions, and even age / cycle count, it's enough to get an approximate idea. I use Eneloops and in most cases wait until the system low-battery message appears to charge them. Until then, BatStatus gives me a rough idea of where I am in the discharge curve and when I'll need to have a freshly charged set ready.

One problem I have with BatStatus is that when the calculator has been on for some time, the reading it returns often “sticks” and stops updating until the next power cycle, and no matter how much the battery voltage drops it will keep returning a stale value. I have no idea why. This seems especially prone to happen after the low battery annunciator has activated. In that case, I frequently have to power cycle in order to be sure I'm getting an up-to-date reading.