Instead of breaking out the multimeter (most of my lights don’t have voltage check) is there something cheap that can quickly tell me what the voltage of my 18650/21700/26650s is?
I have one of these mounted inside my cabinet door — you have o solder some longer leads to it though
most chargers will read out the volts when you first insert a cell.
that is the easiest way
or just get a dvm and leave it out with test leads connected.
wle
I suggested this, but then deleted my post because I figured Bort didn't feel like bringing out a charger.
This sounds like what Bort is looking for. 
^Thanks
Just be aware, they’re pretty much disposable after a while, unless you want to resolder.
The hair-thin (not kidding) wire that goes to the slider breaks at the slider from constant flexing. I went through 2 of them, which is all I bought. Didn’t feel like resoldering at the time, and mostly just stick ’em on a meter.
I’d just use the meter…it’s just as fast and accurate as anything else really.
This is the knockoff version of the ZTS battery checkers. Quality seems to be ok mostly and they’re really convenient to have around. Fine for flashlight cells but they are much more useful for alkies and all the various coin cells because it actually applies a load (which is the correct/proper way to test a cell rather than a simple voltage reading…and which often is a truth teller for cells that may appear to have good voltage but drop like a rock when any load is applied…great for watches and car key fobs, etc).
Price seems higher than normal on US amazon…can find these much cheaper on aliexpress, too, but watch the shipping games they are playing over there now. https://www.amazon.com/Universal-Battery-Self-Check-Capacity-Batteries/dp/B08JQ3R69M/
The cheapest ZTS mini model is going for $45 USD now, for reference, and then they shoot up to about $100. These cheapies are pretty decent, though.