Problem powering sensor from external battery (100000mah)

  • Hi,

    I'm building a MySensors postbox sensor that will sit inside our postbox at the end of the drive and alert us when post has been delivered.

    The sensor has been running in 'beta' for a few weeks powered by my Mac USB port. The controller is based on the Arduino Uno with ethernet shield and NRF24L01+PA+LNA SMA antenna. All working perfectly!

    Now that my China shipment of a 100000mah battery has arrived, time to move onto the next stage and power the sensor by battery.

    The postbox sensor consists of the following items:

    • Mini USB Nano v3 ATmega328P 5V FT232RL (Arduino)

    • SR-501 (motion sensor)

    • DS18B20 (digital temperature)

    • NRF24L01+PA+LNA SMA antenna wireless receiver (with 4.7uF cap)

    • 8 pin socket adaptor for NRF24L01+ (5v to 3.3v step down)

    The battery provides 5v via 1A and 2.1A USB connectors. The problem that I'm having is being able to power the sensor. It will initially be powered for approx. 15-20 seconds and then will switch off. This appears to be consistent each time.

    If I power the MySensors ethernet controller via the battery, it remains powered and doesn't switch off. I therefore don't think the problem is with the battery but may be with the design of my sensor in that may be its not drawing sufficient current that makes the battery think nothing is connected and therefore decides to switch off.

    I did change my sketch so that it didn't power on/off the temperature device (so would be powered all the time) but this didn't make any difference.

    So is it possible that the external battery is switching off because not enough current is being drawn from it? Anything that I can do to confirm this? (note, a novice with electronics...but I get by! ;-)).

    Update: It's possible that the battery is not fully charged...I'll stick a voltmeter over it first to see what its currently holding and may be a 12hr charge will fix the issue...??



  • Sorry this isnt a helpful post, but is 100000mah a typo? 100 amp hours out of something that fits in a mail box? Seems very high.

  • Hi,

    I had wondered that myself prior to purchasing but having seen similar battery capacities on the AliExpress website, presumed it was correct... Looking now, I think it could still be although the picture says different (description and model number state 100000mah).

    This is the model that I purchased:

    They also do a 120000mah version as well...similar physical size:

    I'll leave my unit charging overnight and see what happens tomorrow...suspect that there may not be enough juice to run the sensor...


  • Hero Member

    Sorry to be that guy, but I agree, 100.000mAh/100Ah can't be right. A car battery is like 60Ah right? So, fake ... bought a few crappy batteries from China myself so I'm not judging.

    If you want a legit 10.000mAh battery, look for the Xiaomi one that has just started selling. $15 or so. About what you could expect in that form factor and for the price. But I guess that all those mAh could be ruined by self-discharge, no idea really what chemistry they use.

    If I were you I'd move to a 3.3V system entirely, use a Pro Mini, and try with AA batteries and a regulator. Even the one linked from the store. Do you need the PA+LNA? Did you try with the regular module?

    I've run the SR-501 for many months now on two AA batteries and no regulator. A lot more activity than a mailbox too. No sign or any issues because of dropping voltage yet (but I expect it will happen).

  • Yeah, I guess it sounded too good to be true! 🙂
    I've contacted them anyway for clarification and I should be able to raise a dispute and get my money back (it wasn't that expensive and no doubt can still be used...).

    Its still early days for me so getting familiar with electronics again and playing with Arduino's is fun...and certainly for the moment, 5V works for me...but I hear what your saying. Looking forward to the new boards that will be available hopefully soon via MySensors to allow further experimentation in that direction with AA batteries...

    Yes the distance between the controller and sensor is pretty large and the standard NRF24L01+ units couldn't handle it.


  • i did notice in the AliExpress page for your battery, the illustration has 10,000 mah. The title must be a typo.

  • Yeah...I'm coming to the same conclusion that the typo exists in the description and the model number...

    Either way, I've charged the battery up and connected it to the sensor yet it powers down after 15-20 seconds... Anyone have any ideas why? I can connect the battery to other electrical equipment (e.g. my controller) and that works fine....


  • Admin


    what is the voltage on the output terminals for the following scenarios:

    1. unloaded (nothing connected)
    2. Regular equipment that works as intended
    3. Sensor that shuts down.


  • @tbowmo


    So I've investigated my sensor setup a little further...unfortunately in the process I accidentally shorted the power connectors on the Nano so now it doesn't work so well...leave that for another time! 🙂

    I have a replacement that was on my original prototype connected to breadboard so was a little more careful in measuring voltage - on the Nano and on the step down board. I'm reading 4.8volts which I believe is to be expected.

    I also changed to an alternative battery source but this demonstrated the same problem.

    However, what I did discover after replacing some of the components to assist in eliminating what was causing the voltage to drop off is that** if I just have a very simple connection between the Nano and the battery (so literally only connected by the USB cable), I see the same thing - that the Nano powers itself off after 15-20 seconds**...

    So does that imply that I've a duff Nano board...? 💥

    Anyone else have this board that can confirm a similar behaviour...?

    To be clear, this is a Nano DCCduino with 5v, 3.3v connections powered by USB ( I also have a Nano v3 ( and that too powers down when connected to a battery via USB! No one else seen this...??


  • @nutcracker I think the best way to test the function of this battery pack would be to test it using it's designed purpose. So i suggest connecting a heavier load, (for example a smartphone) and see if it also turns off after the same time. or if as you (and I) suppose it stays on because of the extra current draw.

    I also have a battery backup system for my phone and it turns off if the current draw drops below a certain level so as to stop my phone from trickle charging after it reaches 100%. (it has a button to start the charging function, it doesn't charge when i just connect the phone.)

    Hope this helps.

  • Hi @Gambituk,

    The original battery pack (10000mAh unit sold as 100000mAh :)) as well as another that I've borrowed (9000mAh) work as designed, e.g. able to charge my iPhone with no problems... However, when you plug just the Arduino board via USB into the battery pack, they don't...which is real shame as this would have been ideal for my project.

    Waiting to see what happens with the MySensor board (@axillent) that are being discussed and close to finalising as may be a AA battery, NRF24L01+PA+LNA SMA antenna and ability to have a couple of sensors is all I really need...


  • hello,
    i know it is late, but others could see it too.
    i had the same problem running small (LOW POWER) modules on power banks, because the battery or power bank has a built in power meter, while it is charging and consuming power, there will be power on the USB port, but the arduino's consumption is very tiny regarding charging a phone. you need to disable this feature somehow.

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