WittyPi 4 L3V7: What is the maximum power that can be supplied through the UPS?

Hello forum,

as answered here, the TP4056 charger is able to charge the UPS cells with 1A current (which I've now tested and what I can confirm).

This question aims at the opposite: Is there a maximum power that can be stepped-up by the WittyPi when connected to a (large) block of 3.7V cells?

My Pi Zero + WittyPi 4 L3V7 is offgrid and performs document scans every once in a while. When using a single Sony US18650VTC6 Lithium-Ionen Akku, 3000mAh, Flat-Top cell (fully charged), the Pi is able to power on and perform ~30 scans before being undersupplied and not being able to boot properly. I then tried to increase the amount of scans by attaching a pack of 4 (fully charged) Samsung INR18650-35E 3500mAh 3,7V - 18650 cells, but this happens: The booting starts but the WittyPi turns off exactly when the attached scanner performs its initilization routine, which is triggered when the Pi's USB hub is powered during boot (high peak consumption). The single cell was able to handle this, but 4 cells (in parallel) cannot?

Is this an issue that is solved by switching to another cell brand?

Or is there a maximum current that can be supplied/stepped-up by the WittyPi which could be related to this behaviour? Both cell types measure 4.2V. The setup demands ~1.4A at peak (seconds) (I measured a maximum of <1.5A when powered through USB).

Thanks for any help on this strange behavior,

best, electrobee

Edit: These are the specs of Samsung cells:

• Cell Size: 4/3 A
• System: Li-Ion
• Voltage: 3.6 Volts
• Capacity: 3500 mAh
• Connector Type: Flattop
• Cardboard Sleeve Wrapping: Bare Cell
• Cell Type: Industrial
• Height (net): 65.3 mm
• Diameter (net): 18.2 mm
• Net Weight: 50 g
• Max. Charging Current: 2 A
• Max. Discharging Current: 10 A
• Internal Resistance: 28 mOhm
• Manufacturer: Samsung
• Manufacturer Part No.: 27260