Hi there! Many thanks for stepping in with your experience here. It is greatly valued as I am relatively new to this.
The multimeter shows 1 but its not amps, just milliamps
Okay! I wondered what that small 'm' meant. Got it. The thing I don't get about this is that the CR2032 3V battery I removed from the small light normally gives an output of 20mA, as indicated by this article. So how is it that the light was equally bright with the earth battery as it was with the standard battery? I imagined the brightness would be dimmer with just 1 milliamp.
you set the multimeter in the 20 mA range while expecting 1A
Very much appreciate this tip. I won't forget now that I know.
If you hold the multimeter terminals in your hand you will see that you provide that much yourself
Can't get any reading from my body. Tried all the settings.
but if its dry enough it acts as an insulator. At that point you only have a fancy antenna which picks up electric noise in the house. That solves the mistery of fluctuating power.
The earth has been kept moist throughout so I don't see how the fluctuating power could relate to this. Weirdly the power output went down to 2.5V yesterday morning and spent the day rising back up to 4V where it sits this morning. So, the output is fluctuating even more now. Which seems odd to me.
Anyway, thanks again.
I have bought more copper and will prepare a set-up in parallel to increase the amperage.
The battery can provide 20mA, that's right. But that is just one side of the equation. The current flow depends on the load, the LED in this case, which only needs about that 1mA (these candle LEDs have a built-in resistor).
The battery output depends on the anode,cathode material and the electrolite between them. You use some uncontrolled composition soil so the results are uncontrolled too.
Your soil has a neutral PH, which won't do much work. You need a bit more agressive stuff, maybe add a little acidic solution (vinegar for start)
And use longer screws, so they go deeper into the body. The larger contact area means larger currents (and larger current will deplete the battery faster).
And I forgot the flux stuff yesterday. Solve zinc in muriatic acid for a diy flux. I usually peel off tha casing of a used non-alkaline AA battery. You will need as many zinc as the acid can solve.
AND DON'T INHALE THE GASES WHEN YOU SOLDER!