I have some 18650s that are genuinely 2800mAh and believe there are 3.4Ah (panasonic) ones available. Beware of ebay claims - "real" 18650s should way around 45g each. The 9000mAh ones are about 600mAh!!
Mike.
Thanks, Mike.
The Panasonic ones on amazon are about $13 each. Add to that a good charger and I'm up to
roughly $80 to get started. Add in another spare set of batteries and the total is $130.
Another way I might increase the available power is to use a phone power pack.
They have a built in charger. If they perform as advertised a 16000mAh setup is about $33
and a 26000mAh setup is about $52.
For the time being, I have elected to try a third way of using 4 alkaline D Cells (13000mAh each) at about $1 each.
Not the ideal answer for size or for batteries out in the cold but I only get days here and there below 0 degrees F.
Also, may only get about 3 months between battery changes where I would like 6 to 12 months.
So this still remains to be worked on in months to come.
Not sure I can reduce power consumption much more than I have with the equipment I am using.