I have experience with a couple regular Mark IIIs and now have three LR Mark IIIs. The two that are around my immediate area are on different codes for transmitting, and have done well. Until last winter that is.
I have had the ISS stop sending. It is the version with the circuit board in an oblong white box, with the solar panel on a pivot out base and a wire to hold it to one of three positons. It is NOT the round one with the solar panel fixed vertically.
It stopped sending last winter and I assumed it was a combination of a unit I had gotten off the internet with a lesss than happy battery, plus a cloudy winter. When the temps warmed enough to allow me to retrieve it, the 6 volt battery was down to about 3-4 volts, and swapping a used, but 'conditioned' gel cell with a nice multifunction battery tester/conditioner/charger with nearly 6.2 volts seemed to do the trick. The local supplier of batteries wanted way too much for a replacement, so I went with one I thought tested good. Now just recently, maybe 4 months after the swap, the ISS has stopped sending again. I haven't retrieved the unit yet, but we have had a very sunny summer, and the panel output was indicating voltage sufficinet that it should have kept a battery charged, or even brought a somewhat low one up on it's own.
Further, right now the unit, despite being in the sun, still isn't transmitting.
I'll of course check the battery and also voltages coming from the panel when I start in on this, but I'm wondering if there are voltage steering or charge regulators on the motherboard that could be shot since all the rest of the unit seems to function as it should except for this annoying problem.
Has any one had a Mark III with charging issues? Is it repairable if sent in or is it now mainly trash? I like the way it functions otherwise and in this particular situation I would even consider running DC up there and putting a charge on the battery through some self-added access and terminals just to keep it going.
Dale