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From: The Natural Philosopher <tnp@invalid.invalid>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: Backup power supply
Date: Thu, 14 Mar 2024 09:17:21 +0000
Organization: A little, after lunch
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On 14/03/2024 07:57, Andriy D wrote:
> This is exactly my concern - I want this think up&running 24/7/365 and I don't want
> it to burn my house down 🙂
> I guess this is where you'd say 'risk' and 'price' are in a inverse relationship 😉
> 
> 
> -- 
It is entirely possible to trickle charge a lithium cell at uber low 
risk, Essentially you want to current limit the supply at at one tenth 
of the hourly capacity so e,g a 2200mAh celll would need to be charged 
at no more than 220mA, and voltage limit the charge at 4.2V.

That will give you a cell which, off charge in UPS mode will slowly 
decay to an end point of around 3.5V.
You will need a step up converter to deliver a sane 5V to the pi and 
some way to power it all down in case of battery going too low.

That's probably a case for a Pi Pico.
Or buy a unit that's already done it all :-)


-- 
Those who want slavery should have the grace to name it by its proper 
name. They must face the full meaning of that which they are advocating 
or condoning; the full, exact, specific meaning of collectivism, of its 
logical implications, of the principles upon which it is based, and of 
the ultimate consequences to which these principles will lead. They must 
face it, then decide whether this is what they want or not.

Ayn Rand.