Thank you, Danaco! It is interesting how the second cell is the hottest. Maybe it has higher internal resistance than the others.
I discovered shortly after taking those images that warm cell finished first. So it could have been heating from end of charge. The other 3 took about 15 min longer to finish charging.
I take the images with an Infrared Solutions thermal IR camera. They were later purchased by Fluke. It looks like the Ti50 but has a 160X120 sensor. Unfortunately being an older IR camera it does not have the IR fusion ability. More pics to follow.
Ahh, does the charger change to a trickle charge afterwards?
AccuPower AccuManager 10.
Yes, it switches to trickle charge after full charge is detected.
I am working on the La Crosse BC-500 now. It is a little baby charger that will work from 12V car adapter also. Pics soon.
I’d go further and say it is an unwanted feature. Besides, if I wanted to cook my eneloops, I’d get an i4. 
That is an idea. But I’d prefer it as default behaviour simply because in event of power loss I don’t want it to reenter a charge cycle (for a period of time) and then trickle charge.
Here is your poll:
La Crosse BC-500
Wow, this is a toasty little charger. Hotter than boiling water. You could get burned by this thing. I am shocked.
Charging 4 PowerEx AA 2700 fully depleted.
Charge is 500 mA. Claimed by La Crosse.
These images taken about 90 min after starting charge. The temps may still be climbing. I will post more pics later if so.
BC-500
Something inside this charger is cooking itself.
Could be a regulator with poor heatsink. Hopefully it is not about to die from overheating. :~
It is now showing one of the cells as defective. I think not, it is a brand new PowerEx AA 2700. I assume it reached a thermal limit but not sure.
I never knew this little charger had such poor performance. Once it cools down I will disassemble it and see how it is made.
Took apart the BC-500.
The hot spot is a buck regulator. Mounted to the PCB as heat sink. The hot spot on the top side of PCB is the inductor for the buck regulator. Obviously components are running pretty close to limits.
Here is a portable travel charger with folding plug on back.
Charges at 450 mA each AA cell.
Not fast but seems to run cool enough.
No model number, in fact nothing at all printed on the charger.
I believe it goes by GLE903 or something like that.
I finally got the i4. It is the rev 2 hardware with current limited to 375 mA with 4 batteries.
How can a charger get so hot on just 375 mA per cell
Here is the hard data. First image is about one hour after start of charge on 4 PowerEx AA 2700 that were fully discharged in a C9000.
The amazing thing is that the charger just keeps getting hotter and hotter. The temperature never seems to stabilize, just keeps climbing. But I guess you all know this already. I did take the back off to see what is going on inside thermally. It ain’t pretty.
Ejnoy the images.
After 1 hour.
Back.
Back off looking at circuit board.
Hotter and hotter.
That looks sickeningly hot, for a charger. I have some wall wart PSU’s that get very hot but they are quite old so some inefficient design can be forgiven. Thanks, Danaco.
These are fantastic pictures danaco. I actually find them very fascinating. Thanks.
Hottest part of charger: ~45°C
Actually the hottest part of charger was about 72C close end of charge. The batteries are cooler than the charger body. Shows heat flowing into the batteries from the charger.
From where did you get that i4?
It was sent to me by a friend. New in box.
ok, I was hoping to find a source, I recently got one from FT that cooks similarly!