ESP hackers, what is your preferred method for dealing with the charging voltage of

Electronics
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ESP hackers, what is your preferred method for dealing with the charging voltage of a lithium ion based battery? I haven’t tried it, but I suspect the 4.1-4.2 volt charging voltage would place undue stress on the esp. Using a simple LDO between esp and battery is easy, but the dropout voltage wastes power… Buck converter would work, but not much headroom… What other options are there?

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Gordon,

Holtek do a nice range of linear, low-voltage regulators which are LDO, but more importantly have a very low quiescent current requirement. I’m a big fan of the HT7333 series for battery powered ESP projects. The only thing you need to watch for is the difference in specs between different suffix numbers.

http://www.holtek.com/english/products/power_1.htm#HT71xx-1

Based on experience with depleted, AA Alkaline cells, I’d say the HT7333 would work fine with your Li battery.

                                            John
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I found a switcher on Pololu.com that’ll run down to Vin of 0.5v, Vout 3.3v … I’m curious to see the results.