WemosD1 Battery Shield



  • Does anyone have any first hand experience here?

    https://www.aliexpress.com/store/product/Battery-Shield-For-WeMos-D1-mini-single-lithium-battery-charging-boost/1331105_32679485736.html - I see they are not being sold any more????

    I'm trying a number of options in building my Wifi Temp Sensors based on some of this previous info shared here :100:

    https://github.com/PaulRB/WemosSensor

    When I use a 14550 AA 500-700mAh Battery to the LiPo port, it runs flat after about 1-2 days... when I connect the battery directly to the Wemos / no Shield it can last for weeks.

    Any thoughts / suggestions?



  • They are still being sold -- you just linked to a store page where you can buy them.

    The ESP8266 on the D1 Mini board actually runs on 3.3V. Since it has to be powered from USB, which is 5V, there is a low-dropout linear voltage regulator on it, that drops the voltage from 5V to the 3.3V required by the chip. As all linear regulators, it does that by burning the remaining energy as heat.

    A single-cell LiPo battery has voltage between 4.2V and around 3.6V (you shouldn't discharge it more than this, or you risk damaging it). The battery shield has a boost converter on it, that converts that voltage into the proper 5V that is then passed to the board's 5V pin, and regulated down to 3.3V by the linear regulator. Both the battery shield and the regulator will waste some energy doing that. This may be one reason why you see more energy usage with the shield.

    Another reason is that the shield contains some elements that may draw current even when the ESP8266 is in deep sleep. That could affect the battery life greatly over long periods of time.



  • The LDO regulator on the D1 Mini is actually probably not the culprit. It's quiescent current draw is 25-50 uA, so it doesn't waste a whole lot when the D1 is in deep sleep.

    You might find more information on the battery shield below. It's based on the TP5410, which is a boost regulator chip. While @deshipu is correct that some efficiency will be lost here, a loss of 10-20 mA/hr required to kill the battery in 1-2 days seems way too high to me. While there's no English datasheet, it looks like the TP5410 only has a 10 uA quiescent current.

    You might get better help by elaborating on what you're doing.

    More reading:
    https://arduinodiy.wordpress.com/2017/01/02/reviewing-the-wemos-battery-shield/
    http://harald.studiokubota.com/wordpress/index.php/2016/08/20/power-usage-of-wemos-d1-mini-ws2812b-rgb-shield/



  • I would rather suspect the capacitors on the battery board, then the boost converter itself.



  • Thanks All, I've tested a few batteries now... and will share a simple log from Thingspeak showing the data.

    I'm going to over the next few days move the Battery to directly connect to the Wemos and run the test again.

    Will come back to you.

    My 3 test Batteries & Logged Data here - https://www.dropbox.com/sh/373ppys712l5lz7/AACHgQ2EoV99p9tsdBuPlwuga?dl=0

    Thanks!



  • Just ordered a couple of these for myself since my home brew solution was a bit bulky. Let us know your conclusion, I'll be very interested to hear it.



  • with shield you may use battery + protection board, or you be very disappointed...
    of the few pieces that I bought, not a working one left at this time.

    this is standard graph of battery capacity ;) result of dead TP5410
    alt text



  • I don't think it makes much sense to measure the battery voltage after the shield, like you did -- the boost converter will try to stabilize it as much as possible. It would make much more sense to check the voltage entering the shield.



  • this is measuring on the battery, not after shield, AND this is graph for 2 hours.
    a few more examples, graphics for 20 days. in all cases the charging port is not used, it is already defective. i'm charge the battery directly.

    ESP-201 + DS18B20 + 1000mAh (no battery shield)
    alt text

    D1 Mini + BME280 + battery shield + 1000mAh
    alt text

    D1 Mini + DHT22 + battery shield + 2000mAh (TP5410 completely dead)
    alt text

    D1 Mini + DHT21 + battery shield +1000mAh + SolarPanel ;)
    alt text

    ps: maybe i'm somewhere wrong in the type of sensor...



  • I wonder where those sudden increases of battery voltage come from -- they seem to be co-related with the temperature. Or maybe that's just the sensors reacting to the voltage change?



  • @deshipu
    maybe the sun, affecting temperature measured by the sensor and power generated by the solar panel ?



  • battery up = myself charging, with solar panel -> charging everyday ;)



  • @megazaic
    Hello.
    Could you write some information about your solution (D1 Mini + DHT21 + battery shield +1000mAh + Solar Panel). Pictures or technical things? Please ;-)

    Thanks



  • @razd
    panels
    alt text

    and basic construction
    alt text

    yes, solar panel goes directly to USB charging port, and this scheme has been working for more than 8 months.
    do not ask me why it has not burned down yet. i do not know, probably i have lucky ;)
    datasheet TP5410 tell that this chip can accept up to 10 volts input, and this one still work...



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