ESP32 and CR2032 battery

[noblerabbit]

Hi,

If I only use BLE on esp32, is it possible to run it on CR2032? I assume WiFi is the biggest reason for current spikes?

Thanks.

[woofy!]

The CR2032 is not really a suitable battery.

I use 3*AA batteries with a low quiescent LDO 3.3v regulator.
It wakes up every hour and sends a data packet over WIFI.
Its been running outside for 10 months so far and the battery volts is currently 4.2v. I'm expecting well over a years life out of this.

[i0x915]

Hi,
Which ldo do you use ?
Would HT7833 be a hood option for an 18650 battery

Thanks

[PeterR]

A resistor voltage divider is an 'option' as are LDOs (which essential are dividers).
Depends what you want to achieve; how much deep sleep, how much run time, how long between recharge/replace etc.
The HT7833 has a 4uA sleep draw, an 18650 battery has like 2.6 A/hr?
So about a year sleep? You do the maths. Interesting that woofy suggests an expected year use, maybe he has some bad arse batteries or I'm on a downer...
Anyway, it depends on you're; run duration, run duty, run current demand requirements.
I think your question started around an inability to supply start up current? May help to note that; 1/Rt = 1/R1 + 1/R2 ....*
You're battery datasheet should quote internal resistance & this might help get you better power use (rather than flushing down an LDO/divider!). Albeit maybe with more batteries - but there may be a sweet spot!
Its time for Excel man!
Welcome to the world of system design!
* EDIT: Rather than power up current be limited by internal resistance, provide more parallel batteries. Series and divider is more certain, accepted, but less yield.

[ESP_Sprite]

Just spotted this and want to correct it; the rest of your post is pretty much correct:

A resistor voltage divider is an 'option' as are LDOs (which essential are dividers).

A resistor voltage divider? For an ESP32? Absolutely not. ESP32s can draw from a few uA up to 500mA. Keeping the voltage constant over that current usage range with a resistive divider is impossible. (Unless you want to burn tens to hundreds of Watt in the resistors.)

[PeterR]

Hey, I was going left field to make the point - it depends on what poster needs to achieve.
Clearly dividers sucks but it might be an option (ok cannot think when, even when mains supplied would not to be 'green').
An LDO and resistor divider will both suck when active. EDIT: to say; an LDO will be cool when ESP sleeping.
So I was being somewhat facetious & pushing for details; the run duration, duty cycle, run draw etc.
The poster left all that out...