This week, Linux Out Loud chats about when closed-source services fail you.
Welcome to episode 34 of Linux Out Loud. We fired up our mics, connected those headphones as we searched the community for themes to expound upon. We kept the banter friendly, the conversation somewhat on topic, and had fun doing it.
00:00:00 Introduction
00:01:13 Sense Hat
00:09:57 Game Sphere
00:13:33 Plasma Emojies
00:17:22 Failed Closed Source
00:44:14 BlockCAD
00:51:16 Game of the Week
00:55:02 Gaming Rack
00:58:09 Close
@CubicleNate i’d strongly recommend a low voltage cut-off between your battery and the boost controller.
You probably already know this so this is for everybody else…
Boosting voltage means even if the battery falls below nominal voltage (the point damage will occur with further discharge) the boost converter will keep pushing that dying voltage up to a steady level until the battery can no longer provide enough watts to support the minimum amperage demands of what the boost controller is wired into. That means the device will happily run the battery into the ground.
Ideally you always want your own low volt cut-off but a lot of devices cut off automatically if voltage drops below the minimum for their chips to operate (assuming the designers had the nominal of your battery chemistry in mind). Sadly boost controllers prevent this soft protection from working.
So, a little digging, it looks like I should have my low-voltage cutoff to be 15v to stay in the safe range. I am going to check and see what DeWalt uses in the tools to cut off the batteries to verify. Thanks again. I am looking at possible solutions for the cutoff circuit now.
Nominal for a Li-ion pack is usually a multiple of 3.7v and max charge a multiple of 4.2v. I’m also seeing 15 cells in the pictures.
That’d make it a 3 in parallel, 5 in series pack and…
nominal (empty): 3.7v * 5s = 18.5v (where you’d want cut off)
Max charge: 4.2v * 5s = 21v
I don’t know if their “18v” uses a special chemistry though, i’m reading the individual cells in their “20v” are 3.6v nominal and might be 4.1v full? but they’re also different cells.
They also seem to be doing 20v as a marketing gimmick because it’s describing max charge instead of nominal like their “18v” and this is just my guess but they could be advertising a 3.6v nominal when it’s really 3.7v in order to boost the battery life at the expense of premature wear.
If it was me, i’d open the battery and get the spec sheet for the the serial number on one of the cells or i’d just assume empty is 3.7v and fully charged is whatever my official charger brings it to.
