Something sure seems odd if you've seen this or similar with two batteries now. Interesting and I sure would like to find out the cause.
I've been charging and running my SDS100 from nothing more than a computers USB port. I know the USB spec says the ports shall provide 500 mA of current each port. The fact I can operate plus charge at the same time tells me my computer can probably put out more current.
I watched my bus voltage after mentioning that and it reads 4.85 VDC when the radio is on but not charging the battery.
I let the radio run on battery for about an hour earlier so I could do a test of charging while the radio was also on. When doing that, the USB Bus voltage drops down to 4.63 VDC on the SDS100 display. I don't have one of those USB voltage thingee's you put inline nor do I have a hacked up USB cable so I could not read the true voltage with a good DVM. No idea how accurate the voltage sensor is in the SDS100. I guess the good thing is it is reading the voltage internally in the radio so any voltage drop present at the radio's USB port should be reflected in the radio's voltage display. Now I wonder what the voltage must drop to in order for it to throw the Low USB bus voltage warning.
I have had the low usb bus voltage warning before when using a bad cable. It was a pretty sloppy fit in the jack on the radio also. And that was using a decent wall wart capable of 3 amps or so.
I've been running plus charging my SDS100 using the computer's built in USB port for several months now and that has never failed me.
I did plug the cable into an actual wall wart once after I discovered the USB port voltage readings you could enable in the display settings.
I wanted to see if a 3 amp wall wart would actually show right at 5.0 VDC but it did not. It also read about the same as using my computers USB port as the power source. I think it was a whopping 0.02 VDC higher so not anything to worry about. This told me there may be voltage drop in the connector at the radio or simply from the USB cable itself.
Post back after you watch your USB bus voltage levels. I'm curious as to what yours read. Mine does return to 4.85 volts as soon as the charge is complete and the charge indicator LED goes back to green, The voltage indicated does not fluctuate any when the battery is charging from near dead or when almost full so the charging circuit in the SDS100 must maintain a fairly steady charge current from flat to full.
One thing I didn't do was watch the bus voltage while cranking the audio way up but I did have the backlight at 90% the entire time of my tests. That should have put a little load on my power source.
Are your contacts on the batteries and inside the battery compartment good and clean? When the battery cover door is locked in place, is it putting firm pressure on the battery for a good connection internally? A poor connection at that point could probably do weird things but I don't think anyone has reported an issue with that yet.
I do wonder when people will start reporting that their batteries are not making a good connection any longer. I think most of us know that the foam Uniden uses to keep the battery good and tight will eventually compress and no longer keep things good and tight in the battery compartment. I never had the small battery or its door. I do wonder if the smaller setup also used foam to keep good contact between the radio and the battery. This just seems like a poor way to do things in my opinion.
Good luck with it and hopefully you can find the cause!
