Update on the Greenworks Elite vs G-MAX battery/charger situation
First off, my apologies to the OP for continuing to hijack this thread, but I felt compelled to close out this mysterious issue.
To recap, I purchased a pair of Greenworks 40 volt Elite batteries and discovered that they won't recharge in my G-MAX chargers. I then purchased a new Elite charger, and the Elite batteries charge properly. There are dire warnings on the Elite charger not to charge non-Elite batteries, so I don't attempt to recharge mt G-MAX batteries in it. When the OP suggests that there might be a difference between the output specifications of the Elite and G-MAX chargers, I retrieve the manuals for the two different chargers are reply that they are the same, and that both chargers output 2.2 Amps. So, the problem is a mystery as to why the Elite batteries won't recharge in G-MAX chargers.
This mystery is now solved, due to some recent revelations that I found on Amazon. A review was posted by someone who purchased a Greenworks Elite L-600 (6ah) battery, complaining that it would not recharge in a G-MAX charger. Another person commented that they had no such problems, and that the ONLY difference was that the charger output as shown on the label was 2.2 Amps, whereas the the reviewer's label indicated that it was 2 Amps. The reviewer's charger label had a date code for year 2013, whereas the commentor's label showed 2016. So, I took another look at my G-MAX chargers, and indeed their labels showed 2 Amps rather than 2.2 Amps. These chargers had date codes from years 2012 and 2013. I had made my assertion that the output was 2.2 Amps based on a G-MAX model 29482 charger manual, but then saw that the publication date of the manual was 06-11-16, long after manufacturing dates of my G-MAX chargers ! After reviewing my OPE purchase records, I realized that this manual was from a G-MAX tool purchase that I had made in August of 2016, but had never used the charger. I found that charger and the label on the back with a date code from late 2015 showed an output of 2.2 Amps ! So I placed my Elite batteries in it, and voila, they both charged up ! I next rummaged though my collection of old manuals, and found an older G-MAX charger manual with a publication date of 12-10-12 that showed a charger output of 2 Amps. Finally, I tried recharging one of my G-MAX batteries in the new Elite C-220 charger, and it successfully did so without any drama. So, apparently, Greenworks made some sort of change to the G-MAX charger during 2015, but did not add some sort of revision letter to the part number or ever document this change. This went under the radar until something that changed with the circuitry in the new Elite batteries made them incompatible with the older generation G-MAX chargers. It now seems very possible that there is no significant difference between the Elite chargers and the newer G-MAX chargers. I still have a few days remaining on my free Amazon return window for the Elite charger I just purchased, but unfortunately like a fool I have already discarded the box and cut the warning label off the cord. Oh well, now I have a spare charger for my Elite batteries.
The attached photos show the differences between the older and newer G-MAX chargers and manual.