@adamaero if you're building pretty much any kind of circuitry, you'll eventually find a 'scope worth it's weight in gold. Two things: make sure whatever you buy is FULLY WORKING, and remember that the ground clip is connected directly to the electrical plug ground pin - meaning scope ground IS Earth ground. (Many have vaporized a circuit on accident...)
4
Hmm, lithium battery question. For an emergency backup role, the typical charger IC would cycle the cell(s) infrequently. Would it be better to add a slight trickle-charge to them, matching their leakage current, so the charger almost never cycled?
@rdtsc I've heard a commandment "Thou shalt never trickle charge Lithium batteries."
I suspect that the rationale for this commandment is that a Lithium battery is sensitive to overvoltage. Lithium batteries also have a relatively slow self-discharge (leakage).
By the way, how big will your battery be? How much current will it need to provide when your circuit needs backup power?
Was thinking 18650 LiFePO4 3.2V x 7 in series = 22.4v/2.2Ah. This is for a battery-backed Raspberry Pi home automation server. It's powered from a 24v/15A supply (for LED lighting) via a buck converter, and consumes about 3W. So those cells should power just the Pi through ~17h of power outage.
