Rechargeable Coin Cell Development Board

[@ProtoG42]

Links to equipment used in the video: Hot Plate: amzn.to/2lWRRxL Hot Air Rework Station: amzn.to/2lYCAMU Laboratory Stand with Clamp: amzn.to/2MXOkeb ESD Safe Electronic Assembly Gloves: amzn.to/2u1xdAQ ESD Safe SMD Component Storage: amzn.to/2KDESQq Type 5 Solder Paste Syringe: amzn.to/2NwtH9Z

[@PatrickSullivanJ]

I'm excited to see what you do with the rechargeable coin cell and esp32. I've seen some really cool ultra low power esp projects and will last a very long time on a single coin cell.

[@vibrion121]

I'm intrigued with the zig zag pattern. Is that the power line? A delay line or printed coil?

[@ProtoG42]

It's called a serpentine track and it's used to match a pair of traces so that the signals arrive at the same time. In this case, I'm using it for purely aesthetic purposes.

[@vibrion121]

Proto G i thought that. I ve seen a lot on motherboards

[@MarcelHIC]

Why is the wire length on the pcb critical on a charging circuit?

[@ProtoG42]

It is not. I commented below stating that I used serpentine tracks for purely aesthetic purposes; Meaning, that I used them because I think they look interesting/pretty.

[@BrunoPOWEEER]

Yeaaahhh... this is an interesting and very handy project specially for the IoT devices, the ESP32 can achieve very low power consumption when idle... you can always add a second parallel coin slot somewhere in the pcb to make it suitable for applications where they’re more demanding on processing/transmitting data or require longer periods between charges. This is certainly a very useful product for IoT, just target their groups and someone or company will likely inject some money =]

[@ProtoG42]

I'm going to make some improvements and hopefully open up a tindie store to sell some of them.

[@eamondo2]

How long can an ESP32 run off a standard coin cell? I imagine it varies based on the cell itself, and with something that small it would also vary based on the load. Similar question, do you know if that would be sufficient to run a BLE chip? Something for a positioning beacon, or a low power locator tag? I can't imagine the range would be very far, but it might be cheaper for somewhat single-session use-then-recharge applications than to go all the way to a lipo of some kind.

[@ProtoG42]

That's a question I don't know the answer to and is partially the reason for making the board so I can test it. The ESP32 could perform some task and then go into a deep sleep mode. Directly from their website, "Engineered for mobile devices, wearable electronics and IoT applications, ESP32 achieves ultra-low power consumption with a combination of several types of proprietary software."

[@eamondo2]

I had seen the power ratings for a cut-down version of that board, and they looked like they could run off a coin cell, but didn't know if those translated into practicality at all. I have seen some projects that use the deep sleep mode interrupt to squeeze every last drop of power. I figure for anything other than short burst transmits, it would either not have great range or abysmal runtime.

[@ProtoG42]

Yeah, I'm not sure about the ESP32 but if it's better than the ESP8266, that's a good sign KZbinr Andreas Spiess configured an ESP8266 to run for 17 days transmitting once an hour. Hopefully the improvements Espressif has made to the ESP32 will let it run a bit longer than that. You can always use an 18650 but the point of a coin cell is to have something small like a key fob.

[@simonmerrett]

You may want to watch this kzbin.info/www/bejne/enXTpnWAjqt9bbs about ESP32 (wifi) power consumption. It's not promising, relative to the ESP8266. I did ask Sprite_tm about reducing the ESP32's "BLE" below around 100mA in a March Hack Chat. His answer: "Lower-power BLE: Yes, we're most certainly doing things in that direction. (That is also one of the reasons the SDK isn't visibly expanding: 'lower-power modes' is only a small bullet point but can take a huge effort to get done.) I can't tell you how much lower that is going to be, though." Perhaps worth waiting for but getting familiar with Nordic chips may be the way to go if you're in a hurry.

[@ProtoG42]

Great video, but he was shooting for a 1 year battery life. His results are promising to me and it will get even better with time. According to that video, I should get around 290 hours of battery life before needing to recharge. With a solar panel, it would last forever in Florida.

[@LerrySanders]

Send one to Dave Jones to his mailbag and let him play with it.

[@amd6474]

where did you get those usb type c connectors?

[@drmed92]

I think esp8266 uses too much burst current when transmitting for a coin cell to provide. In contrast, an arduino nano 3.3v with sleep mode. may just be appropriate for logging temp, humidity, etc..

[@ProtoG42]

This is an ESP32, not an ESP8266. Directly from their website, "Engineered for mobile devices, wearable electronics and IoT applications, ESP32 achieves ultra-low power consumption with a combination of several types of proprietary software." Also look up Andreas Spiess. He set up an ESP8266 to run 17 days on a coin cell.

[@moebiusfan9545]

Did you ever place the boards for sale?

[@4647540]

Very nice and we'll organised workshop.....👍👍

[@ProtoG42]

Thank you!

[@hommepomme4750]

Id be very excited for a detailed workshop tour!! I think I recall you saying its on tour todolist?

[@gregclare]

Hi Proto G. You said: “pre-heat the board before turning the hot plate up to the full temperature”? Does this mean your Baku 946A can actually be used to do a full reflow profile? Just curious, as the video appears to show you using the heat gun for the final reflow? I’d been looking a Lafras’s “ReflowR” on Tindie, but can these electronic hot-plates do the same job? I see they are spec’d for 100 - 350 degrees (celsius?), but do they support electronic control for a reflow profile?

[@ProtoG42]

The hot plate does heat up well beyond soldering temperatures but does not have an automated reflow profile. I will reflow with the plate if I'm doing more than more board at a time. The hot air station is much faster for a single prototype.

[@gregclare]

Sounds like a project! I wonder if anyone has done a teardown to see how easy it would be to access the thermocouple and element control, to retrofit a heat profile microcontroller? These electronic hot plates are now quite cheap on AliExpress.

[@beachboardfan9544]

WAAAAAAA coin cells are rechargeable!?

[@ProtoG42]

Do not try to recharge regular coin cells. They make rechargeable versions in the same packages. Usually it will have LIR in front For example a LIR2032 is a rechargeable CR2032.

[@beachboardfan9544]

Hows the lifespan on them, get many cycles out of them?