Hi all, I am a beginner and I am trying to figure which type of LiPo rechargeable battery I need to use on a same breadboard / PCB Adafruit ESP32-S3 and Tiny-2040 connected each other. Is 3.7V for the battery ok? What is the range of ampere? 1300/1450 mA? I cannot see this type of info around.
I expect the best thing to start off with is to get a digital USB ammeter - I have an old one, and I think I paid the princely sum of £5 on eBay for it! Here is one for a similar price. You want something that will do current and cumulative current - the latter will let you measure for an hour or so, to see what the consumption is with the fluctuations ironed out.
Once you have got a bunch of measurements, you can use that to determine what battery you need, given your consumption and expected time between recharges.
Thank you! I am going to follow your suggestion
The two things to look at when you pick your battery are
Maximum Continuous Discharging Current
And Capacity (the mAh ratting)
The maximum continuous discharging current needs to be higher that the current reading you get for the current drawn by your two devices. This should only be a concern if you go with a very small battery. Given what you listed above, it likely won’t be a worry at all. I don’t think your current draw is going to be anything substantial.
Once you do get your current draw, you use that to calculate your mAh requirment.
mA times hours of use between charges, you want to get.
Thank you! My initial thought was using the device suggested to check singularly the current drawn by the single device under the wanted behaviour, sum those 2 currents and add a (made up) 30% extra on top. The approach that you explained is going to work with that usb device? or I need something else?
You should be aware of the fact that current depends on voltage. The pico and probably the ESP32-S3 are not ohm devices. With falling voltage the current rises.
The pico e.g. draws around 25mA at 5V without peripherals, and 53mA at 3V. The ESP32-S2 (!) is at 30mA (5V). During WLAN transfers, you will see very short spikes up to 250mA, but your equipment will not see that and these spikes won’t really contribute to overall current consumption.
So don’t worry about the LiPo because of current draw. Even the smallest LiPo will do fine. But as @alphanumeric already pointed out, you will have to calculate how long your system should run.
If you don’t use advanced sleep-modes or even turn the systems automatically on and off, your project will not run a single day even on a fairly large 1200mA LiPo.
Thank you for the hints, didn’t know that “sleep modes” will affect so much for a case like mine. I will have a look
You can check some of the plots I made for various sleep-modes here: GitHub - bablokb/pico-sleepcurrent: Test programs to measure current consumption during sleep for the Pico to see the impact it has on current. But this greatly depends on your specific use-case.
great that would be useful as main guide thank you