As I reported in my previous posts in this thread, I got very different battery run-times with phantom power on.
From Dec. 24:
"Over the last two days, I had run the DR100mkii with a bunch of different rechargeables. The best I got with one pair was 52 minutes.
Then I tried a stereo mic with less of a current draw then the first mic: 4.5 mA total vs. 6.4 mA total.
No big surprise: the batteries lasted longer. I got 1 hr 55 min. using the same Eneloops as my first test where they had lasted only 40 minutes."
From Dec. 27:
"I ran my Beyerdynamic 930's into the XLR of the DR100mkii, using rechargeable Eneloop AA's, with phantom power on, 24/96, and got just under 1 hr 40 min recording time. "
So the mic current draw affects the battery life, and perhaps also how strictly the mic requires a full 48V.
All the batteries had juice left in them after the DR100mkii would not work with phantom on. Sometimes when I switched the phantom off, an extra bar would appear in the display. (And sometimes a bar would disappear as soon as I had switched on the phantom.)
Yes, the AA batteries got quite warm, sometimes fairly hot.
The other variable is how good are the rechargeables, and which ones does the DR100mkii like. The same eneloops which only got me 52 min on a stereo mic, then got me 1 hr 40 min with the Beyers.
But before I ran the second test, I had drained those eneloops down to zero and did an all-night recharge.