Always wanted to try this hack after reading some of the older posts. Finally got the chance to convert my spoiled single 18650 charger, into a battery holder with ebay 1.99 voltage meter.
You can search for you meter in Ebay with these keywords "RC 1S-6S Lipo Battery Voltage Indicator Checker Tester"
I have to say it works pretty well. I have already bought more 18650 holder for this purpose.
It may not be as accurate than DMM but I feel that it is sufficient for most general usage. Much more convenient to check through multiple cells at a go too.