Problems with mUSB-> WIDE but WIDE->mUSB ok

Hi all, i am trying to make my strompi3 1.72c work correctly for my needs.
Backround info:
The module will stay in a meteo station for our local paragliding club, the RB is a Pi3 B+ and has a RTL-SDR stick, a serial->usb converter for the meteo station (setting it on serial0  did not work due to dirty chars comin in in combination with the solar cell controller) 
The system has 50+10w solar cells and 3 7amp battery in parallel going to the solar cell controller.
I got the strompi for two main reasons
Schedule a night  sleep (we do not fly at night so the station is usless)
Do a secure shutdown in case of energy failure (easy with 2 days of rain and no solar recharge)
the system eats up 1.1Amps@5v , atleast it's what the chinese usb amperometer told me,and the RTL stick is a big energy eater..
I configured the thing to work from 9.00 to 21.00, then it will shutdown.
I modified the shutdown script to shutdown after 40 seconds, and the strompi timer to 60 , so i have 20 seconds to shutdown the services.. 

What happens?
When i connect the mUSB the led glows red, and the system starts,  THEN I connect the 12 volt on wide.
the system boots correcty the red light stays on.
When i remove the 5 volts, mUSB the  blue light glows, and the system shutdowns correctly.
and this works exactely as it should.
the problems start when i apply power on the mUSB again:
Blue light stays on, red rapidly flashes for less than a millisecond
Red Led flashes with 1 second hz period 5% duty cycle.
On the serial i get 

forever, and ofcourse powerfail count grows.

if I disconnect mUSB i get a final xxxShutdownRaspberryPixxx, timer start , raspi shutdowns and strompi too..

If i disconnect the strompi from the raspi, transition form red to blue works, and also from bue to red again when i apply back the mUSB supply, so it seems a load realated issue but the thing absorbs just 1 Amp.
the same thing happens also if i remove the strompi from the rasp, but i connect the high amp source to the power in of the rasp, rasp will power on, but as son i remove and put back the 5volt source of the mUSB primary input blu on , red flashes with 1 second hz period 5% duty cycle.

I tried also the other configuration
WIDE->mUSB  all works perfectly fine.
Did not try the LfePO battery stuff beacuse i do not have a lifepo , but just a RC plane 1S  1000 amp Li-Po, I could try it just to make a test

I attach my config:

Time: 10:46:54
Date: Friday 19.03.21

StromPi-Output: Wide

StromPi-Mode: Wide -> mUSB

Raspberry Pi Shutdown: Enabled
 Shutdown-Timer: 60 seconds

Powerfail Warning: Disabled

Serial-Less Mode: Disabled

Power Save Mode: Disabled

PowerOn-Button: Enabled

 PowerOn-Button-Timer: 10 seconds

Battery-Level Shutdown: Disabled

Powerfail-Counter: 14

PowerOff Mode: Disabled
WakeUp-Alarm: Enabled
 Alarm-Mode: Time-Alarm
 Alarm-Time: 09:00
 Alarm-Date: 01.01
 WakeUp-Alarm: Monday
 Weekend Wakeup: Enabled
 Minute Wakeup Timer: 30 minutes

PowerOff-Alarm: Enabled
 PowerOff-Alarm-Time: 21:00

Interval-Alarm: Disabled
 Interval-On-Time: 00 minutes
 Interval-Off-Time: 00 minutes

Wide-Range-Inputvoltage: 11.746V
LifePo4-Batteryvoltage:  not connected
microUSB-Inputvoltage: 5.285V
Output-Voltage: 5.057V

OF course this is the one with WIDE->mUSB as it was the last i test i did..

I am a electronic eneneer with all sort of stuff. (oscylloscope ,digital logical analizer and protocol analizers, all sort of testers, smd hot air solder station etc etc) so no problem to make tests and / or mods on HW, ah and course also a embedded programmer, was just to lazy to setup the stm environment.

PS, in the future  would be nice to have a heartbeat watchdog autorebooter (no reply from raspi after 60 seconds?, ok reboot it) obvously  with the possibility to dosable it.

Let me know for my issue..


19.03.21 11:22

So Playing around with the code, recompiling and flashing

#define minUSB  1800 
in main.h , and bringing it around 1500 seems to make the trasition now work... 

Joy.IT  .. could the sove the issue?

I ordered a battery hat anyway... just to be sure..
I will update as soon i got some news...


19.03.21 20:10

Hello Alessandro,

thank you for your message. We are sorry that your StromPi doesn't work the way it's supposed to.
It is true that this could be a load related problem. Are you sure that your power source is able to deliver the 1A?

If that is the case doing the following steps could help:

1. Disconnect the StromPi from the Raspberry Pi and from every power source. Pull of the CAP-Jumper, wait a couple of seconds and put it back on. After that check whether the problems remain.

2. If StromPi is still causing the same problem we recommend reflashing the firmware. You can find a file that also includes a manual in our download section.

If there are still any problems you can contact us again at any time.

Best regards,



22.03.21 14:49

Hi Niklas,
I did all the tests i could do, with the cap, withouth the cap.. with the battery , withouth the battery.
I also tried all firmwares from 1.41 to 1.72c with ofcourse the correct scripts, as here we are in lockdown so there is plenty of time :-)  lol

It seems that asson the wide steps in, the board is unable to pass to mUSB, and this happens anso with the LifePo Hat, that i sent back at this point (thanks to amazon) as it does not solve the problem.. the only way the life hat worked it was using the WIDE->BATTERY path, but my system has 21 amps battery to the hat would be just an other extra thing..

The Power supply gives about 3 amps, and ofcourse i tried with al least 3 other PSU, and a powerbank with more that 5 Amps..
Putting a Usb Amp Meter  i get a 1.5 /1.8 Amps for a couple of seconds then it goes down to 1 Amp, i think this is due to the supercapacitors.
An other thing is with the system off, asson i give power mUsb with the wide connected, it goes immediately to WIDE (blue led) and the red blinks as told..
The only wayt to get the red light on is giving FIRST the mUSB power and THEN the  WIDE., then the red  led will stay on, asson i remove the mUSB switces to blue, and when i re-apply the mUsb it will flash rapidly..

So my analysis is  that this is clearly a mUSB path related problem.. 

All this is now RESOLVED recompling the 172C Firmware and setting the define in the header file  main.h to
#define minUSB  1500
 instead of the original
#define minUSB  1800
I think this will higher up the tollerance of the power path relability... but i'm no expert

I could try to fine tune it to 1600 or 1700 to see where the correct threshold is..
If the dev team says that 1500 is good value i could keed it.. so please tell them and let me now..

PS i opend a Tiket, just for reference and to take track of, maybe in the next release i could be configurable or slightly lowered.


22.03.21 15:55

Hello Alessandro,

it is true that this looks like a problem concerning the mUSB path. The fact that the StromPi can not be powered on using the mUSB port after shutting down is a big indicator that this might be a hardware related problem. You also wrote that you tried various power supplies so it can only really be a problem concering the hardware of the StromPi itself.

Because of this we recommend sending the device back to your retailer.

Best regards

Niklas Tritschler


23.03.21 12:38

Yes Niklas, it could be a HW issue,
In truth it never worked fine stock, this until I flashed the firmware 172c with the modified minUSB value.

This guy here seems had my same issue but maybe was not skilled to play with the source.

Anyway setting the minUSB to 1500 in the fimware header seems to have solved the problem, in the meanwhile i will keep it, so as long it works, the truth is that the strompi3 is now at 1200meters altitude high up in a mountain and here we are in lockdown, so it could be a problem to send back, atleast in the immediate..  :-) lol
finghers crossed..

In the meanwile could someone in the dev team tell me if setting that value to 1500 from 1800 is safe thing, or could bring to some unwanted problem.
This is the most important info for me to know now. 
Thank you for the help you gave me 


23.03.21 13:27


it is not normal that the threshold needs to be adjusted to 1500 for the StromPi to boot. If the device does not work with the number set to 1800 than that means that the voltage drops to below ~4.3V which is a pretty low number.

We are happy that you found a solution that works for you though and if the device continues working without any problems than you can keep the settings the way they are now.

Best regards



25.03.21 10:59