Tuesday, 9 October 2018


This evening ive made the connections to the phone's battery terminals permanent. At the same time, I made up a 2k4 resistor (which is a non-standard value, so made with a pair of 1k2 in series) to mimic the measured resistance between the 2nd contact (NFC antenna) and 3rd contact (ground) on the battery.

Supply and BSI resistor

 With a bit of cutting, it will now be possible to fit the original back cover on again!  The 2k4 resistance did indeed turn out to be the devices BSI signal, the pin being shared with the NFC antenna. With the resistor in place and the supply voltage set to 4.35V (the full charge terminal voltage of a 3.8V Li-ion cell) the device is now perfectly convinced that it has a fully charged battery attached.

All cores running WU's - 100% battery!
So my previously defunct and disused Samsung Galaxy Ace 4 is now a fully working BOINC number cruncher! There is however still the issue of heat to deal with. A quick measure with my IR thermometer shows PCB temperature of nearly 50c. Solving this is easy of course - just a fan. But it will take some thinking about to develop a mounting solution.

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