Battery Hat - charge issue

Hello all,

I use 4 raspberry PI4 B, with new strompi 3 and battery hat (1000ma)

All is working as expected, except the charge of the battery,
All units are in charge since about 4 hours.

On 4 units, only one seem to charge the battery correctly:

Wide-Range-Inputvoltage: 12.55V
LifePo4-Batteryvoltage: 3.363V [100%] [charging]
microUSB-Inputvoltage:  not connected
Output-Voltage: 5.057V

On the 3 others, I have:

Wide-Range-Inputvoltage: 12.447V
LifePo4-Batteryvoltage: 3.144V [25%] [charging]
microUSB-Inputvoltage:  not connected
Output-Voltage: 5.054V

It seems to be stuck at about 3.15v.

There a reason for that? Or the batteries are dead?


S. Reillon

15.06.21 16:05

The configuration a the strompi 3:

Time: 14:08:33
Date: Tuesday 15.06.21

StromPi-Output: Wide

StromPi-Mode: Wide -> mUSB -> Battery

Raspberry Pi Shutdown: Enabled
 Shutdown-Timer: 60 seconds

Powerfail Warning: Disabled

Serial-Less Mode: Disabled

Power Save Mode: Disabled

PowerOn-Button: Disabled

 PowerOn-Button-Timer: 30 seconds

Battery-Level Shutdown: Disabled

Powerfail-Counter: 0

PowerOff Mode: Disabled
WakeUp-Alarm: Enabled
 Alarm-Mode: Minute WakeUp-Alarm
 Alarm-Time: 00:00
 Alarm-Date: 01.01
 WakeUp-Alarm: Monday
 Weekend Wakeup: Enabled
 Minute Wakeup Timer: 01 minutes

PowerOff-Alarm: Disabled
 PowerOff-Alarm-Time: 00:00

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

Could be usefull,


S. Reillon

15.06.21 16:12


thank you for your message.

Charging the battery hat to 100% can take up to 6 hours.
Once the battery is fully charged, the little orange LED turns off.

We recommend waiting until the LED turns off. After that you can check the voltage level of the battery hat.

If the battery is not fully charged, even after waiting 10 hours, than it is very likely defective.

Yorus sincerely,

Niklas Tritschler


16.06.21 09:53

OK, thanks,

I turned off the raspberry but not the strompi 3, just to see if it made any difference, and .. Yes, definitely yes. The charge was much faster ...

So it meant that the consumption of the raspberry limited the battery charge. And even more if a device is connected via USB. I suspect, the PI4B's USB uses a lot of power. (more than PI3B+)

how exactly does strompi work? (Sorry if it's already been asked)

Is the external current charging the battery, and the raspberry is powered by the battery (when a battery is plugged)?

Or does the external current supply the raspberry directly, and charge the battery?

Is the external (wide or mUSB) power have limited output current (5v output)?




S. Reillon

16.06.21 11:43


the external source is powering the Raspberry and the battery. There is a little charging circuit on the Battery hat that regulates the current that is used to charge the battery. When the primary power source fails or is turned off, the battery starts delivering power to the device. In that case the charging circuit is turned off, to prevent the battery from charging itself.

When the main power source is reconnected the charging circuit is turned back on, so that the current that is used to charge the battery is regulated to a constant value of 200mA.

The StromPi can deliver up to 3A, but this only works if the power source that is used is able to generate a 3A-current without dropping its voltage.

So if you want to get a current of 3A out of the StromPi, make sure that the power supply is powerful enough. This is especially important to keep in mind when mUSB is used as power source, because a lot of Micro-USB power supplies are not able to deliver 3A.

Yours sincerely,

Niklas Tritschler


17.06.21 11:34

ok, thanks. I will check that.


17.06.21 22:59