I'm hoping that someone can help clarify for what's happening with my Nimh batteries. I have 4 battery packs. They are all the same. Wattage 800 Mah Nimh packs. I have a Reedy Pro charger ($200) . I charge these packs at .6 amps. Before charging, I always discharge them with the charger at a rate of 3 amps. I usually get a charge of 720 - 740 mah. Recently, I left the battery in the plane overnight, connected but with the switch turned off. When I went to discharge the battery before charging it again, It was completely drained already. My charger has a digital read-out so I can tell how much is going in when charging and how much is going out when dis-charging. To finish the story, in this case, the battery took a charge of a whopping 852 mah. More than ever before. To be certain that this was not a fluke, I again left another battery pack in the plane over-night. And, I got the same high charge of 845 mah.

Did this happen because the batteries were COMPLETELY discharged in the plane versus when I discharge them using the charger. Does the charger possibly have a built-in baseline for discharging that won't allow the batteries to be completely discharged?

Any help would be appreciated.

Yes. The battery charger will discharge the pack to about .8 volts per cell. If you let the batteries run down because of drawing current on their own, they will discharge as far as they can. I am still not familiar enough with NiMH cells, but I do know that you should not do that with NiCads, because of the posibility of the weakest cell reversing its polarity. The rule of thumb in conditioning NiMH cells is to fast charge at no more than their rated capacity, and discharge at no more that twice their rated capacity.

Les

High discharge rates heat the battery, and can give a "false" low voltage reading due to the heated cell having a higher internal resistance than a cool cell. thus, the bateries could read at .8 v per cell and still havemore retaned energy than if they'd been discharged more slowly.

If the packs are discharging overnight in the plane, even though the switch is off... there's a problem with the switch or the wiring of the system. (maybe the switch is cutting off the power from the motor, but not from the RX... Where in the crcuit is the switch? between ESC and motor of between battery and ESC?)

BTW: The high charge rate you are normally using could alo be a be a problem... an is the most likely case for you to consistently get the 720 to 440 mah capacity from your 800 mah cells. It may give a slightly higher capacity just by charging at appx 800 mah (at home before going to field, charg at low rate, at field use the field charging high rate.)