Powering ESP32-S2 from a single Li-ion cell

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mathieu
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Powering ESP32-S2 from a single Li-ion cell

Post by mathieu » Wed Sep 15, 2021 7:44 pm

I just got a S2 Mini board, and I'm trying to power it from a single 18650 Li-ion cell. The 18650 is the input of a HT7333 LDO regulator which nominally outputs 3.3 V. My battery input is ~3.89 V, my output is ~3.25 V, but something does not work as intended (the board should be requesting a URL and it is not doing so). I added 10 uF capacitors to the input and/or output of the HT7333 but no luck.

The board works from time to time, for no obvious reason. I suspect this is a power issue, as the same board works flawlessly when powered from USB.

What would be a simple, reliable method to power this board from the 18650?

davef
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Re: Powering ESP32-S2 from a single Li-ion cell

Post by davef » Wed Sep 15, 2021 9:40 pm

I put 1000uF low-ESR caps on my 26V to 5V SMPS outputs, which are capable of 5A peaks . I also use some 1.5A SMPS buck supplies, which seem to work as well.

Max output current 250mA! Have you got a DSO?

davef
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Re: Powering ESP32-S2 from a single Li-ion cell

Post by davef » Wed Sep 15, 2021 9:58 pm

I'd check that any internal current limiter in the HT7333 can handle charging up a 1000uF at turn-on. I didn't see anything relevant in the datasheet.

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mathieu
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Re: Powering ESP32-S2 from a single Li-ion cell

Post by mathieu » Tue Sep 21, 2021 8:32 am

Thanks for the feedback.

For the record, after exploring a number of options I went with the following option: connect the Li-ion battery to the 3V3 pin of the S2 mini through a silicon diode. The S2 should see voltages in the range of 2.9-3.5 V, which is within specs. This solution is very simple to implement, and should be very energy-efficient

wangshujun@tom.com
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Re: Powering ESP32-S2 from a single Li-ion cell

Post by wangshujun@tom.com » Tue Sep 28, 2021 7:58 am

mathieu wrote:
Wed Sep 15, 2021 7:44 pm
I just got a S2 Mini board, and I'm trying to power it from a single 18650 Li-ion cell. The 18650 is the input of a HT7333 LDO regulator which nominally outputs 3.3 V. My battery input is ~3.89 V, my output is ~3.25 V, but something does not work as intended (the board should be requesting a URL and it is not doing so). I added 10 uF capacitors to the input and/or output of the HT7333 but no luck.

The board works from time to time, for no obvious reason. I suspect this is a power issue, as the same board works flawlessly when powered from USB.

What would be a simple, reliable method to power this board from the 18650?
Ht7333 is a LDO with large voltage difference, which is not suitable for this occasion
The better LDO I used before is tps74701, but now it has been replaced with tps63000 DCDC

elschopi
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Location: Bavaria, Germany

Re: Powering ESP32-S2 from a single Li-ion cell

Post by elschopi » Thu Sep 30, 2021 10:34 am

Not only maximum cell voltage needs to be taken into account, I'd also consider the lower limits of the cell. If battery efficient operation isn't needed, one could use a TP4056 based charging / protection board (which would also handle charging the cell, but then you'll need a relay / FET to disconnect the load while charging) and a step-up board that steps the (say) 2.5 to 4.2 V from the cell up to clean 5V.
I do that when I use ESP32 based dev boards (ESP32 DevKit C, Heltec Wireless Stick) in non-critical testing setups or if backed by solar cells.

In general, you'll want a low dropout, wide input range LDO with a very low quiescent current to maximize efficency.
There's also a excellent video on the topic by Andreas Spieß over on Youtube: https://www.youtube.com/watch?v=FrCgQgahzsI

Also if your cell does not have protection included, you should implement it in your design. DW01-P can be used for that. (https://cdn.sparkfun.com/assets/learn_t ... et_V10.pdf)

best regards,
Chris

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