ESP8266 Community Forum

- Wed Dec 10, 2014 1:17 am #4457

How about the Lithium Thionyl Chloride Battery? (http://biz.maxell.com/en/product_primar ... &pn=pb0004) It's high capacity and capable for high discharge rate. But typical cell voltage is 3.6V, Anyone know is there risk if connect it directly to VCC pin of ESP8266 module? Thank you.

3.6V is actually the upper limit as stated in the application design guide document, however I haven't found any absolute maximum ratings for the chip. For safe measure I would still use a LDO.

I haven't heard about these batteries before, but the stated "Nominal Discharge Current" is insanely low (about 100uA) and if those batteries behave anything like Li-Ion or NIMH, their capacity will drop at higher discharge rates. They also seem quite expensive, a quick amazon search turned up about 15$ for the 1100mAh model. For battery powered applications I would suggest using two AA batteries and a boost converter (e.g. MCP1640 with a large low ESR capacitor bank on the output side), that should actually give you a longer battery life at a fraction of the cost.

- Wed Dec 10, 2014 6:21 am #4481 The Microchip MCP1640 is pretty close to an ideal solution it certainly broadens your supply choices which should compensate for it's quiescent current consumption of about 20 µA...
Think I'll grab one of the MCP1640 evaluation boards and experiment with some batteries

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- Sat Dec 13, 2014 7:04 pm #4767

How about the Lithium Thionyl Chloride Battery? (http://biz.maxell.com/en/product_primar ... &pn=pb0004) It's high capacity and capable for high discharge rate. But typical cell voltage is 3.6V, Anyone know is there risk if connect it directly to VCC pin of ESP8266 module? Thank you.

3.6V is actually the upper limit as stated in the application design guide document, however I haven't found any absolute maximum ratings for the chip. For safe measure I would still use a LDO.

I haven't heard about these batteries before, but the stated "Nominal Discharge Current" is insanely low (about 100uA) and if those batteries behave anything like Li-Ion or NIMH, their capacity will drop at higher discharge rates. They also seem quite expensive, a quick amazon search turned up about 15$ for the 1100mAh model. For battery powered applications I would suggest using two AA batteries and a boost converter (e.g. MCP1640 with a large low ESR capacitor bank on the output side), that should actually give you a longer battery life at a fraction of the cost.

Thank you for comment. Please look at more detail about these batteries from another brand :- http://www.varta-microbattery.com/appli ... _er_en.pdf, As I know, its price below 3USD for 1200mAh at 1ku.

- Mon Dec 15, 2014 4:02 am #4826

Thank you for comment. Please look at more detail about these batteries from another brand :- http://www.varta-microbattery.com/appli ... _er_en.pdf, As I know, its price below 3USD for 1200mAh at 1ku.

According to the datasheet the 1.2Ah model has a max. pulse discharge current of 80 mA (using 100ms pulses every 2min.) while the ESP8266 has a max. consumption of 300mA. I'm not an electrical engineer, but these numbers just don't add up...
You're welcome to try using capacitors to compensate for current spikes, but looking at the numbers, I don't think it's worth the time & effort. Even at 3USD/piece these batteries don't seem very economical. Good AA batteries have about 3.9Wh (using numbers from wikipedia) and cost 50 cent or less at consumer quantities, while the 1200mAh Lithium Thionyl Chloride battery has 4.32Wh at 6 times the price. The MCP1640* costs about 70 cent in single quantities, so even if you add the one time additional cost of the boost converter, using 2 AA batteries costs about the same for the first charge, but give you almost twice the capacity.

*) there might be cheaper or better boost converters, I'm just sticking with the MCP1640 as example since it's the first chip I found that seemed suitable.