Further Thoughts on Dexcom (Still on First Sensor)

The little charge icon on the dexcom, the battery picture, has three bars when full. I get this. When I plug it in and leave it plugged in, the number of bars goes up after a while. I get that.

What I have learned: I recharged the Dex on Wednesday around noon. I did not want to be charging it on Rosh Hashana or Shabbes, which makes for a seventy three hour stretch (I'll have two more such stretches). I was not sure if it would last. Here's what happened: I woke up on Thursday still with three bars, but early it went to two bars. Friday morning I had one bar. Saturday morning I had one bar. Saturday late morning, the one bar started blinking, and I tried to minimize use, but I still had alarms go off and checked it and so forth. Saturday evening when the sabbath ended, it was still blinking one bar.
And that charge up was the quickest yet!

Question: Is there any way to know if the Dex is fully charged when it's charging? Is there anything it does to say it's done, or is the only way to check by unplugging it and taking a look?
Also, any expertise on what makes a charge last longer or go faster? Is it better to charge it when it's at two bars or a blinking one?

I did locate the dexcom website's demo on their software. You can, very blurrily, preview what happens with the software. On Tuesday I'm going to my dad's office where he has a computer running Windows.

I have had one more ??? episode, but it lasted less than an hour and was this morning. Of all the calibrations I've done so far, about half have been within 2%. All but one were within 20%. That one was about 75% off. I think this is overall very good.

The number of fairly flat lines I've seen on the three hour graph fairly well takes my breath away. Of the flat lines I saw on the Guardian in 2008, almost all were due to sensor failure. I saw maybe two legitimate flat lines lasting over an hour in over 100 days' worth of sensor wear. I suspect that this means that I now have more possibility of getting the blood sugars I want, even though I had been assuming that things were getting worse with my body.
I'm also seeing more meal time spikes (I saw almost no meal time spikes on the Guardian) which I think is probably good news about my digestion, but maybe due to a change in diet, of eating lower fat these days.