As a follow up, I also tried:
Olight 18650 Protected for high drain devices (3600mAh, 12.9w, 3.6v)
Fits DevTerm just fine (easier to insert than Nitecore NL1823). Still need to perform reliability tests, but it seems to be charging just fine for now.
As another follow up, I can also confirm the following:
KeepPower 18650 Sanyo Protected (3500mAh, 10A, 3.7V)
Fits DevTerm just fine (easier to insert than Nitecore NL1823). Still need to perform reliability tests. Still trying to verify if battery will charge, but i see no reason why it wouldn’t.
These fit nicely in the battery holder. They’re easy to remove. The battery door fits over them perfectly.
They provide about four hours of fairly continuous use. They appear to be unprotected. They come with a plastic storage box that snaps closed.
any updates on reliability
I got these too (KeepPower 10A 3500mAh - 18650 Battery (Protected Button Top)) and they fit perfectly, no bulging compartment and they are pretty easy to take in and out. They also charge perfectly well within the DevTerm.
Not had mine long to comment on reliability but they are working very well so far.
Trying to guess the power draw:
I’m not good at battery math, and trying to figure the following DevTerm and uConsole use case out: so the Pi 5 will apparently draw up to 12W, and I heard the average SSD plugged in via USB will also draw around 8-10W peak. I would like to be able to use SSDs under all circumstances. Edit: I forgot the modem which mine will have, which i guess can draw up to 10W too (we’re looking at max. peak which this post suggests the modem can reach, not average), and the screen I guess. Edit 2: found numbers for the screen, apparently slightly above 4W for maximum brightness.
Trying to guess the total power budget:
So what, does this put me at some battery that supports something around like, past 35W discharge, does anybody know? That does feel a little high. Edit 3: this post suggests a 30% safety margin, and with all of this I guess we end up at:
I guess that does match the beefier Raspberry Pi 5 45W power supply, but still feels like a lot, so I’m wondering if that’s true? Even the Steam Deck with SSD will apparently draw less than 20W under full load when not charging, so that’s why I’m wondering.
Trying to guess what batteries might work:
Now most batteries have their Continuous Discharge Rating specified in A, not W. Do I multiply that with 3.6V, or with 2.5V (lowest voltage allowed for most of them), or with 5V to get how much Watt they’re rated for without overheating? And then since it’s two cells, is it enough if that covers around 22.5W plus some headroom, or do both need to support 45W minimum? For now, I’ll assume both cells need to meet the rating and that it’s multiplied with 2.5V.
For my use case if we’re assuming 45W is actually true, that makes me wonder if I’d be looking at 20A batteries like the Samsung INR18650-20S with 2.5V * 20A = 50W, if that makes any sense at all. And not the Samsung INR18650-30Q 15A or 35E 10A then, but what do I know. Any input appreciated.
Call for help:
Sorry if this is a silly question, I’m not used to doing this math myself. Can anybody more knowledgeable tell if the ballpark looks correct for my uninformed napkin math? Since the DevTerm and uConsole have both a BMS, I might consider unprotected cells, but I assume they still need to be rated correctly to avoid a fire hazard. And I’d rather be on the safe side.