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Powering nRF52810 with 3.6V Lithium battery

George555

I have designed some beacons based on nRF52810. The software uses the minimum functionality of the radio to transmit some packets every second and sleep.

In their sleep period the beacon consumes around 2-5uA.

I chose to power the beacons with an ER14250 3.6V Lithium battery, 1200mAh.

During an application testing I deployed around 10 beacons that transmitted a packet to a receiver every second. I noticed some of them drained the battery within days which is not reasonable as they should last over 2 years with that battery.

I tried to investigate the problem further. I programmed a beacon to transmit every 100ms.

A week after I found it dead. The battery was completely drained and also the chip was damaged.

I replaced the battery and it didn't work.

I used a bench power supply at 3.5V to check what was going on and I noticed its current consumption was around 150mA which is an indicator of a faulty chip.

The question is can that battery be used for nRF52810? In the datasheet it says absolute maximum at 3.6V yet in the recommended voltage range it mentions up to 3.6V.

So that's a little confusing as the absolute maximum voltage is the same as the recommended operating voltage.

Can that battery cause damage to the chip?

  • 0 in reply to George555
    George555 said:
    We also added an extra 10uF capacitance
    George555 said:
    , do you think that this capacitance is enough?

    According to the schematic you provided, the module already has an internal 10uF capacitor(C19). The recommendation is 4.7uF, so this should be more than enough. The product specification states max. and min. rise times for VCC, so it is a good idea to double check that you are within the range.

    Another concern: AIN0 (BAT_MEAS) only has a 0.1uF capacitor. As a consequence, BAT_MEAS will reach 3.6V earlier than VCC. I have not yet checked whether the product specification states that this is OK.

  • 0

    Looking at chapter 4. and 5.2 in the module's datasheet, the module seems to be quite sensitive. The datasheet also recommends being cautious and "reserve more than 30% of the margin", so this does means operating the module at 3.6V is risky.

  • 0 in reply to helsing

    Thank you for your help!

    I did not notice those extra capacitors. I added them because I wasn't sure about the internal schematic.

    I also took a picture of the module

    Can you please provide more information regarding the importance of the pins you mentioned?

    Regarding the other questions.

    helsing said:
    How is the temp/humid sensor powered? What is the voltage on the I2C pins from the sensor?

    The temp/humid sensor powered directly from the battery. The voltage on the I2C bus is the same as Vbat. SHT31-DIS-B is the part number.

    helsing said:

    How is AIN0 configured internally?

    Could you please measure AIN0 on both the broken and working units? Is it shorted?

    Is it configured to work as analog input pin.

    So far, apart from the high percentace of random battery drain on some beacons I have only one dead product in the lab. I checked every pin with a DMM with respect to ground. no one is shorted.

    helsing said:
    Have you measured the battery voltage in various conditions when brand new? Would you be able to share the datasheet for your specific battery?

    A brand new battery has 3.6V

    I think that's its datasheet

    https://www.compel.ru/pdf-items/eemb/ps/er14250/854b3cfd8bbc0ca8f0eb7f130ed3f8a8

  • 0 in reply to helsing

    Indeed. Although it is very strange to me why they state that.

    If you look at the picture I posted above you can see that the only active part inside the module is the nRF52810 SoC.

    The rest of the circuitries are crystal oscillators, an antenna matching circuit and some capacitors. Nothing that would explain the difference from the SoC datasheet

  • 0 in reply to helsing

    I'm definitely going to correct the capacitance on every power pin of the module

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