Earth Energy Batteries

[FreeEnergy]

http://www.nuenergy.org/alt/nu_energy_sodium_chloride_valve.htm

[Kysmett]

Okay then.  Lets decide what the low end for useful voltage is.  What would be the smallest valid load application?  Garden LED's?  Full lamps for the walk-way?  Any ideas?

[hartiberlin]

all sorts of LED lightning.
Depends on how much power you can draw.
Build the cells bigger and you can draw more power and use high power LEDs.

[betajim]

Okay then.  Lets decide what the low end for useful voltage is.  What would be the smallest valid load application?  Garden LED's?  Full lamps for the walk-way?  Any ideas?

Well, 0.4 volts would make a good cut-off. Most of the transister boost circuits that operate
LED's will stop working below 0.4-0.35 volts. I don't know what the voltage per earth battery
cell is, but build enough cells in series to give a reasonable starting voltage, say 5-6 volts.

For the load resistor, something in the range of 30-100 Ohms and rated at 5 watts would be
reasonable. Then you need to periodically measure the voltage across the load resistor. Use
the voltage measurement to calculate the current and you then have one current, time point
to plot on a graph.

At the end of the test, integrate to get the area that is below the data points on the graph. The
area will be equal to the batteries Amp hour rating. If you supply the data I'll write the program
to do the integration of the data. 

[Kysmett]

Okay, sounds fair.  There is only one other variable.  Soil quality.  I don't have the resources to conduct periodic soil quality and moisture content tests throughout the experiment.  If we are willing to forego that, I will start gathering materials.