The PN-40 gave a low battery warning. Why aren the batteries really dead?
The PN-40 gives you an “early warning” so you will have time to change the batteries without losing data such as your track log. To decide when the batteries are nearly dead, the unit uses a voltage profile which is specific to the battery type. Individual batteries don’t necessarily match the profile exactly. The unit is being conservative in detecting end of battery life, so the batteries will have some residual life. Also, the batteries may briefly recover when removed from the unit. Because the PN-40 sometimes fails to power on after battery exhaustion (see #12 below), it’s a good precaution to heed the low battery warning and change batteries at that time.
