I agree. I have the 536 and keep it constantly plugged in. Unfortunately the poor design doesn't trickle charge the battery while plugged in and turned off.
You always have to leave the radio on to keep the battery charged just to keep the clock set. Now people are having problems with the display fading. My guess is that they leave their radios on to charge the clock battery and it is shortening the life of their displays.
Really dumb design. This needs a tweak with a future firmware update.
Have you tried to charge it for a few hours, then try the power cycle to see if it still happens? It's not a design flaw if it works for most.
I bought it about a year ago. At first it would last for about two weeks, then one week, then one day and now the clock system won't stay charged at all. You are correct in that it may not be a design flaw, but I suspect there may be more failures as time goes on. I don't use my PSR-800 too much anymore, but when I turn it on, the clock is still ticking away.....
How often do you use your scanner? If you know it would last two weeks, does that mean you didn't use your scanner for two weeks then turned it on and the clock was still OK?
If you don't use your scanner much, it may be draining a little each time and not getting a good recharge.
As for the 800, that isn't good. If it uses a battery then one day it will just stop working period.