I am working on a little project at the moment:
I want to supply a old mobile phone (Nokia 3510) with an battery for up to 2 months without charging.
The mobil phone and the battery will be located in the woods, so there are variations in temperature.
The mobil phone is only used to receive a phone call, but there will be no phone conversation (that means the mobile needs low performance).
The supply voltage of the mobile phone is 3.7 V.
My first concept was to take some 18650 Lion batteries and to connect them in parallel (total capacity: 20 Ah).
1. question: do I need PCB or are the batteries protected against deep discharge through the mobil phone (protected or non protected batteries)???
My second concept is a big 30 Ah, 12 V lead accumulator which is regulated down to 3.7 V with an DC DC converter.
But I am not sure if a lead accumulator is appropriate for this task (because of long-term discharge and variations in temperatur)???
2. question: which accumulator (also typ of accumulator) is suitable for this task?
I hope my question is understandable, if there are any quetsions: please ask.