"Tim Ward" wrote in message
...


It looks like there's an opportunity for a data logger update here.

The logger is already in the aircraft. It's generally connected to the
battery.
An 8 bit A/D would give an accuracy of 20 mV across the 10-15V range.
Sampling once per minute or so should be adequate. Post-flight analysis
should give you a pretty accurate idea of the health of the battery..
Battery health information doesn't really need to be real time, since
you're
probably not going to be able to replace it in the middle of a task,
anyway.

Tim Ward


Tim Ward



But it would be nice to know that you are flying with a failing battery. You
can then limit the use of power hungry devices ( Personal stereo, head-up
gunsight or electric shaver ) or simply cut the flight short before the
battery goes duff.

Maxim and others produce 'digital fuel gauges' or coulomb counters that are
compatible with modern battery technologies. These basically measure the
charge put in and power taken out of a battery whilst in-circuit with around
1% accuracy. Laptop and consumer electronics have these built into the packs
these days. It would be simple to read the DFG using your navigational iPaq
but the drawbacks are probably not worth the benefits.

( google Maxim MAX1660 for more info )

Ian