Imperf3kt wrote: ↑
Thu Dec 07, 2017 8:11 pm
Yeah but is that caused by the cable being unable to handle the voltage or the cable being unable to handle the current, resulting in voltage sag.
The problem detected by the Pi is undervoltage, not undercurrent.
Undervoltage can have two (common) causes:
- The PSU itself cannot generate enough voltage, sometimes it will be OK when not loaded (Pi shut down) but low voltage at the running load (current).
This is common with supplies designed as chargers. They may be marked 5V 2A but cannot supply 5V and 2A at the same time.
- The PSU generates enough voltage, but there is a voltage loss in the cable between PSU and Pi at the running current, due to thin and/or long conductors and Ohm's Law.
Both may be related to current draw but the problem in each case is the low voltage at the Pi. The solution may be to improve the current capacity of the PSU and/or cable.
If you must call it "undercurrent", it is "inadequate current capacity". From the PSU/cable POV, it is actually an overcurrent
condition -- the Pi is drawing more
than the PSU/cable can supply without excessive voltage loss.
Your water supply pressure is low. You need either a taller water tower, or a thicker and/or shorter pipe, or just use less water.