OK, this is the best solutions I have found to date, based on the hint by Ampster. I used a standard 50ft extension cord and shorted the live and neutral pins at one end, then tested the ohms from the now 100ft wire, It was between 1 & 2 ohms. Perfect.
I then shorted the battery between the 2 pins at the ST60 in the picture below, and the battery voltage dropped much quicker than any of the previous methods, most notably using a single cell At 3.3v.
Just do short 1-2 second connection times to start, the voltage drops quickly and heat will be generated with large cells. You could use a standard household light switch to turn the connection on and off. Use a multimeter to check the voltage change as you do this.
Make up a strong connection between the wires and you will have a reliable solution. The photo below shows just what I did for testing.
Hope this helps ...
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