Please read carefully
I had the nanoVNASaver running - both (green) LEDs on....
Went to do something else for about an hour...
Came back and my nanoVNA is dead - both LED off
Plugged back to wallwart and the "charge LED " is flashing...
if the nanoVNA is running an app -
and it is plugged to PC via USB cable
does it quit charging the battery?
No "me too" or opinions wanted
*"just the facts ma'am "
yes it quits charging
no it does not quit charging
it needs steady charge voltage and does not charge when connected to PC
via USB port of unknown quality .
( I can easy test that AFTER it gets fully charged - again )
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Battery not changing ?
Please read carefully
It is possible that the cable you are using is a “date only” cable and does not have the wires for charging.
On 12/11/22 8:57 AM, Anne Ranch wrote:
> Please read carefully
> I had the nanoVNASaver running - both (green) LEDs on....
> Went to do something else for about an hour...
> Came back and my nanoVNA is dead - both LED off
> Plugged back to wallwart and the "charge LED " is flashing...
> My question
> if the nanoVNA is running an app -
> and it is plugged to PC via USB cable
> does it quit charging the battery?
This is a surprisingly complicated question. USB charging involves a
negotiation between the "power consuming device" and the "power
supplying device". The "request" is typically set by a resistor between
some of the pins, although there are other schemes with actual messages.
It's entirely possible for a consumer to ask for charging and the
producer to deny the request, and then shutdown the 5V to the consuming
device, while keeping the data connection alive. That decision might be
made at the time the initial connection is made, or when the stack is
renegotiated, or any other time. The USB standard allows all of these.
Worse than that, there's a chain of these decisions all the way down
from the top level USB hub (these are all inside the PC, usually). Since
each upstream port divides into 4 downstream ports, there's a surprising
number of "layers" between the connector on the outside and the top of
the tree. Any tier in the tree can say "I'm not supplying power to
Windows, Linux, and MacOS all have different ways of managing this both
in a "automatic" sense, and in a "manually control" sense.
Back a few years ago, there was sort of a separation of "high current
charger" USB (intended for phones), low power supply USB (keyboards,
mice, and the like). Some wallwarts would put out enough for "low
power" mode but not "high power" mode, so the phone would charge really
Now with USB-C and variable voltages and powers, with 40-60 W charging
(if not more) it's even worse.
So your USB NanoVNA might *connect* but not charge. Or might have
started charging, but then stopped charging. Unfortunately, the actual
chip that's doing this in the NanoVNA isn't necessarily smart enough to
a) indicate unambiguously or b) implement retries or c) be sufficiently
Perhaps others have already mentioned this, but don’t overlook the possibility of an intermittent connection between the USB port on the NanoVNA and the circuit board on the NanoVNA. I have an SAA-2N that I bought a few years ago, but recently it has developed such an intermittent connection. Sometimes when I plug in a USB cable between a 800 mA wall charger and the micro-USB connector, I’ll get red LEDs indicating charging. If I move the cable or NanoVNA while charging, often the LEDs will go out, indicating loss of charging. At other times using the same cable and wall charger, I get no LEDs. Usually if I prop something under the male connector of the micro-USB cable end and let the weight of the NanoVNA ‘push downward’ on the connector, it will make a valid connection and continue to charge until fully charged. I suspect a cold solder joint between the micro-USB receptacle and circuit board. Obviously quite a nuisance, but for now I can work around it. Undoubtedly this method will cease to work, but I lack the sharp eyesight, steady hand, and small-pitch soldering equipment to remedy the problem.
I agree , intermittent connection - we used to call "vakl contact" are
( I believe vakl has origin in German language , but do not quote me )
But my nanoUSB end is solid and have been connected for few weeks . ( I
did post picture of my :"bullet proof "setup long time ago ).
And yes, I own one of those "data on;y" cable somewhere...
Is this a PC or a laptop to which the VNA was connected?
If a laptop: then do check to see if one of the USB ports has a
"lightning" symbol adjacent to it.
This denotes it as, specifically, a "Power Port". A Standard USB2 port
should be able to deliver 500mA.
USB3 (usually blue) up to 900mA
Many (most?) laptops will cut power to the USB ports if they drop into
"sleep" mode and/or hibernate (you said that you'd left the kit alone
for an hour (or so)).
Some L/Ts have a bios setting which controls the battery level below
which it will remove power from even the USB "Power Port(s).
On Tue, 13 Dec 2022 at 19:30, Anne Ranch <email@example.com> wrote:
> I agree , intermittent connection - we used to call "vakl contact" are pain.
wackel kontakt in german .. grin (the double-u is spoken like the v in
Am 13.12.2022 um 14:16 schrieb Anne Ranch:
> I agree , intermittent connection - we used to call "vakl contact"
> are pain.
> ( I believe vakl has origin in German language , but do not quote me )
> But my nanoUSB end is solid and have been connected for few weeks . (
> I did post picture of my :"bullet proof "setup long time ago ).
> And yes, I own one of those "data on;y" cable somewhere...
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