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I want to use a 3.7v lithium-polymer battery to power a 826۶ wifi module in a mechatronic project. This module works with 3.3v and I'm not an electronic expert so I use modules to avoid mistakes and time saving. Despite the fact that it looks like a pretty common problem, I can't find any module to buy. I don't know anything about circuit design but I can learn. So I'm looking for any cheap solution for this problem.

using this:

enter image description here

to power this:

enter image description here

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2 Answers 2

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You should look for a low drop out linear regulator which will regulate the battery voltage to 3.3V

For example a TC1262 from Microchip has a drop out voltage of about 300mV at a normal current consumption of the ESP8266.

If you prefer a ready-made module instead take a look at AMS1117 3.3V modules on Ebay.

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    \$\begingroup\$ That's "a low drop out linear regulator." \$\endgroup\$
    – JRE
    Commented Nov 7, 2019 at 18:31
  • \$\begingroup\$ The maximum dropout voltage of the TC1262 is 650mV...this won't work. \$\endgroup\$
    – Elliot Alderson
    Commented Nov 7, 2019 at 20:06
  • \$\begingroup\$ Indeed, but that is at a current draw of 0.5 A which is not the current consumption of an ESP8266. \$\endgroup\$
    – Jakob Halskov
    Commented Nov 7, 2019 at 20:19
  • \$\begingroup\$ Can you provide a link or citation for the maximum current of the ESP8266? Because in the "ESP8266 Hardware Design Guidelines" from Espressif Systems we see: "When using a single power supply, the recommended output current is 500 mA." \$\endgroup\$
    – Elliot Alderson
    Commented Nov 8, 2019 at 0:13
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    \$\begingroup\$ I guess AMS1117 3.3V module is what I need. thank you. \$\endgroup\$
    – 2012User
    Commented Nov 9, 2019 at 17:38
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A battery's voltage sags as it discharges and the LiPo type is no exception. A 3.7V LiPo battery falls to about 3.0V when fully discharged. You will want your project to continue operating over the full range of battery charge state so you might want to consider a buck-boost converter that can operate with an input voltage down to 3.0V to get maximum run-time for your project.

On ebay, there are power supply modules that use the TI TPS63020 buck-boost IC. I see one for about $10 that should meet your needs. This solution is also more efficient than an LDO so you'll get longer run-time. Good Luck!

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  • \$\begingroup\$ A buck-boost regulator is the best choice, so you can exploit the full voltage range of the Li-ion cell. TI's TPS63020 is a very good one. I would avoid LDOs, too, since they are far too inefficient for battery-powered devices. \$\endgroup\$
    – Diego
    Commented Nov 8, 2019 at 8:58
  • \$\begingroup\$ "This solution is also more efficient than an LDO" - Dropping 3.7V to 3.3V using a linear regulator is 89% efficient. It's very possible for a buck(-boost) converter to be less efficient. \$\endgroup\$
    – marcelm
    Commented Nov 26, 2023 at 12:08

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