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Battery and charging issues - info

StefanoLaiStefanoLai
in Hardware

Hello,

we are using many of your MetaMotionR in our prototypes.
In total about 150 sensors.
FW version = 1.4.4
HW version = 0.3

We are facing 2 main HW issues:

1) Dead battery in about 15 sensors (previously working correctly).
The usb charger works correctly: 5V in 5V pin, 3V in 3V pin and about 4V in BAT pin, when charging.
The BLE connection to your Metabase App works correctly.
However once unplugged from usb-charger, the connection is lost and the battery runs out of charge quite immediately (voltage BAT vs GND = 0V).
Another point: in the same instant the plug is connected to the micro-usb of the sensor, the LED blinks (red-green-blue) ,
exactly in the same way described in the hard reset procedure (shorting of pwr and grd pins)
From a visual inspection of these batteries, there is not evident difference between them and the batteries of sensors working correctly.

2) In other 3 sensors (previously working correctly).
The usb charger works correctly: 5V in 5V pin, about 4V in BAT pin, when charging. However on the 3V pin, the voltage level measured is lower (between 1.5-2.5V) than expected (3V).
For these sensors, it was not possible to set a BLE connection, even through the Metabase App (the sensors are not visible during the BLE scanning).

Do you have any ideas/suggestions about the actions to do in order to fix these problems (or to prevent them)?

Another question. How long can we keep the sensors plugged to the usb-charger?
I mean, can we keep the sensors continously in a "recharging" status?
(e.g. they are plugged and charged, then they are unplugged and used for 30 min, and then they are plugged to the recharger again and keep in a charging status.
This operation repeated many times (years) )
Is the MetamotionR provided with a circuit able to monitor the level of the charging battery and avoid failure of the battery in a similar operation condition?

Thank you
Stefano

Comments

  • EricEric

    @StefanoLai said:
    1) Dead battery in about 15 sensors (previously working correctly).
    The usb charger works correctly: 5V in 5V pin, 3V in 3V pin and about 4V in BAT pin, when charging.
    The BLE connection to your Metabase App works correctly.
    However once unplugged from usb-charger, the connection is lost and the battery runs out of charge quite immediately (voltage BAT vs GND = 0V).
    Another point: in the same instant the plug is connected to the micro-usb of the sensor, the LED blinks (red-green-blue) ,

    Is the battery wiring shorting out the connections?

    exactly in the same way described in the hard reset procedure (shorting of pwr and grd pins)
    From a visual inspection of these batteries, there is not evident difference between them and the batteries of sensors working correctly.

    Are the batteries feeling squishy or have expanded?

    Were you actively using the sensors before these issues happened? Or were they working fine one day, then stopped working the next instant?

    2) In other 3 sensors (previously working correctly).
    The usb charger works correctly: 5V in 5V pin, about 4V in BAT pin, when charging. However on the 3V pin, the voltage level measured is lower (between 1.5-2.5V) than expected (3V).
    For these sensors, it was not possible to set a BLE connection, even through the Metabase App (the sensors are not visible during the BLE scanning).

    Do you have any ideas/suggestions about the actions to do in order to fix these problems (or to prevent them)?

    • Are there any physical defects on the boards?
    • How are these sensors used?
    • Were these 3 used any differently from the others?

    Another question. How long can we keep the sensors plugged to the usb-charger?
    I mean, can we keep the sensors continously in a "recharging" status?
    (e.g. they are plugged and charged, then they are unplugged and used for 30 min, and then they are plugged to the recharger again and keep in a charging status.
    This operation repeated many times (years) )
    Is the MetamotionR provided with a circuit able to monitor the level of the charging battery and avoid failure of the battery in a similar operation condition?

    You can leave them plugged in.

  • StefanoLaiStefanoLai

    @Eric said:

    Hi Eric,

    1) Dead battery in about 15 sensors (previously working correctly).

    • Is the battery wiring shorting out the connections?

    The problem apparently seems that one you reports. I changed one dead battery with another one (swapped from another metawear sensor) and it works.
    Which can be the reason for so many failures?

    • Are the batteries feeling squishy or have expanded?

    No, they are not

    • Were you actively using the sensors before these issues happened? Or were they working fine one day, then stopped working the next instant?

    All the sensors were used actively (room temperature, protected by their cases, never open). Some of these were used almost every day (30min a day) more than 4 months, other a bit less, but at least 2 months of total usage for each sensor (at least 2 times a week for 2-3h)

    2) In other 3 sensors ...

    • Are there any physical defects on the boards?

    No

    • How are these sensors used?

    The same use of the sensors above, no differences

    • Were these 3 used any differently from the others?

    No

    Another question. How long can we keep the sensors plugged to the usb-charger?

    • You can leave them plugged in.

    OK, Is the MetamotionR provided with a circuit able to monitor the level of the charging battery and avoid failure of the battery in a similar operation condition? A battery protection circuit?

    Thank you for your reply
    Best regards

  • StefanoLaiStefanoLai

    @Eric.

    ISSUE1: Dead battery in about 15 sensors (previously working correctly).
    YourReply: Is the battery wiring shorting out the connections?

    The problem apparently seems that one you reports. I changed one dead battery with another one (swapped from another metawear sensor) and it works.
Which can be the reason for so many failures?

    YourReply: Are the batteries feeling squishy or have expanded?

    No, they are not

    YourReply: Were you actively using the sensors before these issues happened? Or were they working fine one day, then stopped working the next instant?

    All the sensors were used actively (room temperature, protected by their cases, never open). Some of these were used almost every day (30min a day) more than 4 months, other a bit less, but at least 2 months of total usage for each sensor (at least 2 times a week for 2-3h)

    ISSUE2:In other 3 sensors ...
    YourReply: Are there any physical defects on the boards?

    No

    YourReply: How are these sensors used?

    The same use of the sensors above, no differences

    YourReply: Were these 3 used any differently from the others?

    No

    QUESTION: can we keep the sensors continously in a "recharging" status?
    YourReply: You can leave them plugged in.

    OK, Is the MetamotionR provided with a circuit able to monitor the level of the charging battery and avoid failure of the battery in a similar operation condition? A battery protection circuit?

    Thank you for your reply
    Best regards

  • LauraLaura

    @StefanoLai,

    There is a PCM on the battery AND a battery monitor + charging circuit on the board.

    Our best guess is that the batteries depleted beyond rechargeable capability (battery drained below 3V).

    You can email hello[at]mbientlab[dot]com and we can send you some replacement batteries for free if you would like. Please mention this in your email.

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