Do you screw in the batteries really tight? If this didn't happen immediately but, rather, after a number of charges it "might" be that the center contact in the batteries has rotated and broken the wire that's tack soldered to it inside the battery casing. I had an m401 battery die on me and opened it up and found that the wire was broken and this is the only explanation I could come up with as to how it could have happened. They use really crappy, single-stranded 30 gauge "wire-wrap" wire inside these things and it doesn't take a whole lot of twisting to break - especially after they begin to corrode with age and dissimilar metals interactions. Also, they don't typically leave any slack or "service loop" at all and the wires that go to the batteries' center pin are usually stretched pretty darn tight to begin with. Which leaves even less margin for movement of the pin.
I just looked at the center pin of my 808 batt and it seems to be anchored pretty solidly as opposed to the pins on my m4xx batts which can wiggle around a lot. Probably not the case with an 808 but what can happen with m400 batts is that the center pin gets compressed down into the cavity and doesn't make contact with the atty's/charger's center pin anymore. From what I gather, it might not be sensing that there is a battery connected. You can take something thin, like the tip of an x-acto blade and very carefully work the put up a little so that it makes electrical contact again. Not sure this can be done with a KR808 but you might try. My 808s are 6 months old at least and maybe they are different now or maybe different manufacturers have varying designs... Otherwise, I'm figuring those batteries are probably shot. :-(
Rick
At least with analogs, all I needed was a lighter.
