Ok, interesting.
The battery did charge. It hit 100% and measured temperature was around 38C, which is much lower than what I saw charging at 2A. But it didn't stop charging there... it kept going and the 100% dropped to 98% and then worked back up to 100% then dropped to 99% worked back up to 100%, etc. Went like this for around 5-10 minutes. The temperature climbed to around 41C (which is a far cry from the 59-60C I saw at 2A) and then it finally dropped out of 'Bulk Charge' mode, went to "Wait EMM", then switched to "Calibrate", then switched to "Maint Charge".
This is different from what I saw under 2A charging where the charge % usually goes up and then at some point around 70% it sometimes jumps to 100% and stops charging.
I need to do this a few more times to see if this behavior is consistent. But looks like battery temperature is more controlled under 1A (which is logical) and I'm curious now if more charge went into the battery. I ran out of time today but tomorrow I will use Battery Amnesia to drain the battery and see if that takes longer than what I saw before. The other curious thing is that I had charged this battery to 100% about 5-6 days ago. I don't believe I have seen it drain fast before but today EMMpathy was reporting around 60% when I started charging it. I don't understand how it determines the % (perhaps based on measured voltage?) but I'm curious now whether the 60% was correct and I never got a full charge due to the temperature cutoff under 2A.
Note that the measured capacity did not change from 1752mAH though. It's still sitting at 1752mAH. We'll have to see if that changes at all after a full discharge and recharge cycle tomorrow.
Anyhow, it does look like this 15V 1A charger works.