low voltage/roast stall

[JamesG]

My modified "euro ninja" profile is working really well, both in terms of following the curve, and the quality of coffee output.

log0011.klog

(69.78 KiB) Downloaded 320 times

As you can see, no longer any issues about following the curve at higher temperatures. Interestingly, both the recent roasts I've done with that profile have had starting voltages of around 215V...

[kaffelogic]

Great work James! This approach is to be commended to all users who have supply voltage issues (below 225V). Essentially you have shown that with a fan speed reduction from 1320 RPM to 1240 RPM for the later part of the roast you can get decent results with supply down to 215V.

[JamesG]

I've added it to the contributed profiles, and will add any others there as I adapt them to my feeble power source...

[domi]

You can keep an eye on the supply voltage by pressing ☰ (info) until you see 'Technical information' then press ▶ until you see the supply voltage displayed. This will help you get an idea of how variable your supply is. From what you are reporting it is potentially all over the place.

FWIW, I did that six times in a row and got all readings between 229 and 232 (our nominal voltage in Finland is 230). When looking at the voltage registered in the log files (10 roasts so far), the average is 229.7498. Highest is 232.709, lowest 225.875 (seems to be an outlier, since second lowest is 228.285).

[JamesG]

I've just looked through my last 10 or so roasts. I think the highest reported voltage was 225V, and the lowest was 215 (and that roast was successful on my modified profile). I mentioned the low voltage issue to my new neighbour the other day, because he seems pretty into electrical stuff (he's an embedded software engineer). And he was pretty flipped out by the low voltage, so is planning to investigate! We're in an area of new houses, so he's been quite careful checking his house's wiring for errors!
Here's the log and successful roast

roast0011.png (40.83 KiB) Viewed 5168 times

[JamesG]

extreme low voltage

Not sure what it is about today, but been trying to roast all day. The best I've had is 214V (won't start), and the lowest I've seen is 200 flat!! How accurate is the voltage measurement, I'm wondering. Will be contacting my supplier of electrons tomorrow!

[kaffelogic]

extreme low voltage

Not sure what it is about today, but been trying to roast all day. The best I've had is 214V (won't start), and the lowest I've seen is 200 flat!! How accurate is the voltage measurement, I'm wondering. Will be contacting my supplier of electrons tomorrow!

We calibrate the voltage measurement to the nearest volt in the factory. We are not intending to be any more accurate than that, but you can be confident of it within +/- 1V.

Below 200V the roaster goes into error state and will not operate. However, at 214V it should still start after giving a warning. However the motor might not be getting enough voltage to tick over. Does it try to start and then stop again? Regardless, I think you do need to follow up with your lines company.

[JamesG]

Our lines company has actually responded very promptly. We'll have a voltage recorder installed on Monday. Apparently because we are in a new subdivision, the whole area is not yet on its permanent supply connection, but they are surprised that it is *so* *low*. At 200V, they'd expect issues with LED lightst & TVs.

And you are correct. At 214V it attempts to start. The motor whirrs for ~1 sec and then shuts down. Below 214, no whirring whatsoever.