I thought I would ask around here because there’s a good possibility that other people have been thinking about these issues also, although I didn’t find a thread about it, maybe because we’re all waiting for it to be released…
Can the battery be directly replaced with 3 or 4 Lithium Iron Sulfide batteries in series? Or can a single Lithium Iron Phosphate battery be a direct replacement? I can’t tell from the image whether a 3.3V regulator is used and what the minimum and maximum dropouts are.
Can the Electron and/or GPS unit power down into sleep mode? I would like to power down most of the time to conserve battery life, then send an email or text message once per day, or maybe on command by SMS. Should the GPS unit power input connect to a P-MOSFET switch that is controlled by a pin?
Also, how is the reception? Will the Asset Tracker receive GPS and transmit SMS through the walls of a building?
And do I need to pre-order early to get shipping at end of January 2016?
Answers to any questions would be greatly appreciated.
Yes it’s a little strange to reply to my own post, but I thought of a really important question: what is estimated power consumption of sleep mode for Electron?
There’s a big difference between the Core (3.2μA) and the Photon (160μA), maybe due to the shutdown feature of the voltage regulator used in the Core? I did some rough estimates on battery life based on a paper measuring smart phone power consumption. If a device records GPS and transmits SMS once per day, using 3 Energizer Ultimate Lithium AA’s in series, the difference in battery life is 1 year 9 months at 160μA sleep versus 10 years at 3.2μA sleep. With 160μA sleep, 3 or 4 D-cell Alkalines would be needed to achieve 10 years.
A lithium polymer battery may not work for some applications. The Sparkfun web site listed self discharge rates of up to 8% per month.
On the plus side, I think the Asset Tracker has a major advantage over other commercial products in terms of price and customization. If it only transmits once every hour, it’s difficult for a professional car thief to locate it with a RF detector. If it doesn’t have to connect to the car’s battery during normal driving, a thief could not locate it by following electrical wires throughout the car.