Lightning Icon has just appeared on screen

I have a Pi 4 which has been running continuously for a few years with no problems.

I have very recently seen the “low voltage” icon appear on the screen. The PSU has an inline voltage display between the official PSU nand the Pi which used to show 5.25 volts. It now shows 5.15 volts with same current (about 1amp).

There have been no hardware changes for well over a year, so does anybody have any ideas what is wrong? Do the official Raspberry Pi PSUs fail like this and is this advance warning of a more serious failure on the way.

A bit of additional info is that the Pi 4 has a Geekworm Cooling fan (with power control) and a geekworm mSATA drive. Both unchanged for years.

I haven’t had any of the official PSUs fail, but I’ve had several 3rd party ones for earlier Pi’s go in exactly the way you describe. There have been no further issues after replacing the PSUs.

I’ve previously reported the quality of the official Pi PSU’s to the Pi foundation after several failures and recall doing a lot of probe testing for them to evidence the voltage droop when the CPU ramps up load. That was back in the Pi1 days though, so I would hope it’s been resolved since.

The PSU’s can run close to their current limit on a loaded Pi, so it wouldn’t suprise me to see a higher rate of failure than you might expect. I’ve since switched to iPad charger PSU’s as they provide 2A+ and are two a penny.

I’ve come across several power supplies that would no longer give their rated current, though none of them was anything to do with a Pi. Components age. A current limit is often determined by a low value resistor; if it goes high, or one of the solder joints is a bit dry, the current limit can fall. The reservoir capacitors have a finite life; the power supply then can often have ripple on the output, so it dips below specification 100 times a second.

Power supplies are, in general, relatively highly stressed, so it’s not surprising that they fail – and sometimes the failure mode is not total.

I can’t recommend using a charger as a power supply, as a charger isn’t intended for continuous use.

Just out of interest, and out of fear of blowing up a Pi, would a BBC Micro power supply (with BBC Micro still attached) be suitable, or not?

All interesting comments. Thank You.

I can’t recommend using a charger as a power supply, as a charger isn’t intended for continuous use.

Seems a good point to me.

Components age

Just like me. It seems my Pi PSU is on its way out and has been replaced,

If anyone wants official Pi 4 PSUs at less-then-retail prices, I have a box full left over from first gen 4tes. The Mk2 machines come with their own beefier supplies, so I have no use for these official ones, so they’re sat in a box looking lonely. Drop me an email if you’re interested.