I am not going to waffle on here. I use it a lot. I've charged Lipo, Lion, Lead Acid even Trustfires on it.
It works and only costs about $30 with postage from Hobby King.
The only thing that might make it better is an exposed ISP port, a serial link and open source firmware. All of which in theory is hackable.
Dave Jones has done an excellent teardown of the Accucel 6 charger in his Electrical Engineering Video Blog. Highly reccomended if you are a nerd like me. Lately I have been spending a lot of my spare time watching his videos, hence the lack of updates in the past month.
Dave if you read this, you are an inspiration and I love your work. I hope you don't mind if I link to your video:
Dave mentioned hacking the firmware to make a constant current dummy load. Ideal for testing those flashed ESCs. I'm working on some code to get the KK2 working under Arduino. Once that is done I might do the same for the Accucel 6.
From what I have read there a lot of clones of this charger and the Turnigy version is a clone also. Other versions included an FTDI chip for interfacing with a computer. I wonder if the firmware still communicates on the USART.
Some people swap out the resistors for higher accuracy ones, but there is a calibration mode for that.
Some guys started writing new firmware for it but the thread died back in 2010.
There is also a load of talk to sift through in the product comments at Hobby King. Also a bunch of crap in the files tab..
Lastly, the place to start the Atmega32A.
For now I am not going to go further with this charger. It does its job perfectly well and until it stops working or I get another one I will leave it as is.