BC66 Hardware Design for LiSoCl2 Battery

I am designing a device using BC66 and is powered from an LiSoCl2(ER14505H) battery. The main Problem i face is the module is not able to boot up successfully from the battery. The system reboots when it tries to connect to network, and this continues. The regulator used is TPS63900. Antenna used was W3544B. There is no information of a proper hardware documentation is available for the design. Does anybody have a design note on a proper power supply design for BC66 or circuit diagram or BOM or anything with LiSoCl2 battery… Thanks in advance.

Common LiSoCI2 batteries, especially the smaller sizes non-bobbin types, do not support high discharge current. You better review the datasheet of your battery and check its voltage at the input of your buck-boost converter. If the voltage drop is still within the conversion range of your converter chip, you can try adding big value capacitors (220~470uF) across the input and output of the converter.

Hi Hobby_a,
Thanks for suggestion. I,ve incresed the overall capacitance to 1300uF(1000uF(Electrolytic), 3x100uF(Tantalum)). It sometimes boots and sometimes don’t. But when i increase the capacitance too much then the startup time of buck boost increases. Also there is a board size constrain also.


Yes the capacitance cannot be increased without a limit. In this case your existing LiSoCl2 battery cannot deliver the required current. You better change it to high current drain type LiSoCl2 or switch to another chemistry.

Yep! i am planing to do so. Thanks for the help.

change battery type from hi-energy ER14505H to hi-power ER14505M

Are capacitors close to the BC66 or close to the battery? Do you use TPS63900 current limiting functionality? What output voltage of TPS63900 do you use?