nanoVNA

[bob91343]

I have two units.  They both worked perfectly and sat on charge for a couple of years with occasional use.

I unplugged them and put them on the work bench.  Now they are both in trouble and I don't know how to fix them.

One does not respond to the power switch.  The battery is fine.

The other powers up normally but within a few seconds shuts itself off.  Every time.

Help please.

[metrologist]

How do you know the batteries are good?

[bob91343]

I measured the voltages.

[Mechatrommer]

Not good enough.. some dead batteries show good voltage on open load.. once on load, voltage goes down like free fall.. you need to verify its mah capacity using a capable charger..or make one yourself.. using a dso and a resistor can do that as well..

[bob91343]

Apparently there is an intermittent.  One of the units now seems to operate normally.