Ok, found the chart produced by HKJ here.
So if we go with the Panasonic 3100/3400 your voltages on the first box correspond to approximately:
- 8.4V - 3 status leds - 100%
- 7.45V - 2 status leds - 50%
- 6.95V - 1 status led - 14%
- 6.45V - 1 status led flashing -0%
So not such a bad spread!
-Garry