The Passport also doesn't play well with normal rechargeable (Li-Ion) cells, since these start at 1.3V and from my testing that's approximately where Passport stops working due to too low voltage.
Did you mean NiMh cells here? Li-ion produces 3.7V. Or am I missing something else?
Oh, you're right; it appears Li-Ions only exist in 3.7V (
according to Wikipedia). Then I will edit my post accordingly.
They explicitly recommend Lithium cells ~ they are very uncommon and expensive. The ones that came with my Passport lasted for probably 4h; while Alkalines last maybe 15 minutes or 30 tops.
I didn't even know Lithium AAA batteries exist. I think a better solution would have been if the device fits 3 batteries. With some voltage regulation, anything between 3.6 and 4.5V can be brought down to 3V, so that standard AAA batteries can be used until they're completely drained. From your pictures it looks like that would mean a slightly wider device.
Myself neither. According to Zach's reply it seems they didn't plan to use (or maybe even know) them themselves from the start either. Apparently, they discovered if they pull whatever currents an STM32 needs (triple digit milliAmps I guess), an Alkaline drains exponentially faster than on lower currents, but since it was discovered very late, they couldn't change the 'electromechanical design'.
Three AAA's with a step-down would fix the issue to some degree (counteracting rather linear discharge curve), but not sure it affects the current issue. Like, that they're apparently not made for higher currents and when used in such scenario, their capacity is crippled.
4x rechargeable constant voltage (builtin charger): 25€
I didn't know these exist! It looks like a great solution, but won't solve the "10-20 years time" problem.
Well, in 10-20 years I can either get new rechargeable ones or also just get available Alkalines. These would be needed if you use the device as a daily driver. To sweep it in the future, a set of Alkaline batteries is enough. They can power it for like 15 minutes easily.