Simple watt meter for the field?

[Hostage-46]

I was watching the action at the TNT this weekend and watched a glider spin in due to what folks in the pits were calling a dead battery.

As a glider guider I generally wear out my neck before my flight pack, however I still feel like I need something in my field box beyond the knowledge of a fresh charge before loading up the car.

Can anyone point me towards a simple low cost insturment I can hook up to my flight pack to ensure I have a good charge?

Dan

[pmpjohn]

Dan,
Watt you need;) is not a watt meter but an expanded scale voltmeter with a built in load. There are several on the market. See what your local hobby shop has available.

John

[Gary Warner]

Dan,

I lost a Psyco on a bad receiver battery a year or two ago on the second flight. First thing that day it was checked on a comercial battery tester and showed to be good. The battery took a surface charge and false peaked a cheap fast charger. If using a battery checker, use it before all flights (I would have seen a much lower voltage before the second flight).

The best advice I can give is to track charge times and peaking voltages to be reasonabley sure the battery has a full charge. To this effect, I now ONLY charge my batteries with a fast charger that records the amount of charge the battery took and the peaking voltage. Considering a constant charge rate (I use 1 amp for my all receiver packs in open class sailplanes) the pack should always peak within about 10% of the known peaking voltage. Suspect packs that change (higher or lower than 10% of a known voltage) in peaking voltage with the consistant charge current. Note that using assorted charging currents will change the peaking voltages.

Also, strongly consider marking your battery packs with the date that they were new and their new peaking voltage. After 2 years replace the pack, good or bad. It's cheap insurance considering the $1000.00 airplanes we fly.

The only times I've lost planes to receiver batteries is when I break my own rules stated above.

Over night wall chargers are on my do-not-use list (except transmitters as mine all have meters and alarms), since I had a battery go bad in an OlympicII and it was on the wall charger all night. Using a wall charger is blind faith, though is well enough for most fliers.

[Hostage-46]

Good advice. I've been using a Supernova for all of my charging needs to date, even for the transmitter, I just remove it and put it on the charger.

Dan