I cannot measure L5 battery internal resistance (mΩ) but let us call it for a second (this exercise time), or “take it” as it is one NiMH AAA battery, instead to the NiMH AA type one, we should not threat it as the NiMH AA size one, charge/discharge the same, with increased current value of twice. Why? Because usually charging rate of high current AA round cell is allowed to be of double Amps value, 1000mA instead of max. 500mA (or 400mA, as linked here). Let us take a look at NiMH AA/AAA charger Opus BT-C2000, actually take a look at current (Amps) values used for particular NiMH AAA or NiMH AA battery from lygte-info.dk, borrowing just one small part his much broader knowledge for the purpose of what I’m trying to point out here.
I wrote above about NiMH chemistry but same rule applies to Lithium-ion chemistry used in L5 battery, it heats a lot because it is not (not based/manufectured on more adequate/preferable background purpose) or probably (for sure) not produced as higher continuous discharge rate (lower capacity) battery and therefore heats up a lot. Why therefore? Because i.MX8M Quad (including cellular modem card, the other one, etc.) drains its relatively weak battery a lot, with quicker rate as it should actually take place there (with 5.7 inch 30Hz display on at least 900mA (almost 1.0A), passive consumption of 900mA, no usage other than L5 display on). As its increased capacity (we are still pretending it is an over-pumped AAA round cell) tells us that it cannot behave the same way as AA battery with the same capacity, this “L5” AAA heats considerably during usage, discharging phase, of L5 and especially heats above its own health acceptable temperature when L5 charged and used at the same time.
I don’t have much practical experience but still know that recommended value for someones cordless (DECT) phone at home, with two NiMH AAA batteries, would be 600mAh (nowadays usually used capacity is 800mAh) and not 1200mAh, as continuous discharge rate during such cordless call would not keep up for very long, and certainly not extend two AAA 1200mAh battery life expectancy. Same applies to someones cordless mouse, you’d rather avoid usage of high capacity 2×AA batteries like much over of 2000mAh (if the one within 1000mAh range not available at your local store). Just my two cents, anyone like to disagree about my approach focused around L5 battery capability to cope with high discharge rate(s), continuous discharge rate(s)? Is this L5 battery rate already known within this Forum?
Let me kind of translate what I wrote above (trying to achieve) and ask here, is it L5 battery certified for continuous discharge rate of 2.0A or not? Do we need battery that can easily cope with 3.0+ Amps continuous discharge rate and stay that way much cooler (although its capacity would be obviously decreased to where batch Dogwood battery was). Should I guess that L5 battery heats considerably more under heavy app load when under 50% (3.8V) of its capacity?
P.S. Purposely not a single word from my side about L5 original charger, actually supported coding (BC1.2/DCP or PD2.0/PD3.0), supported HUBs or anything else, this post is just about L5 battery thermals (if and when inserted, I mean in use, under load during charging stage, under load during discharging stage, …). Or to reuse this important contribution:
reminding us about “lost as heat” and paraphrase it and question myself if current L5 batch battery can live up well with 1.86A (for example) pumping (charging) without any significant battery only/own thermals issue when L5 used in-house, at common room temperature. Same applies to L5 continuous self-discharging amperage rate that is with or without (might heat up too) significant (like phone call or gaming) load, taken from its battery only. Besides anyone considered usage of 4.5V (DCP coding with max. of 1.4A or perhaps 1.5A) as easier to handle or even better (not software related) option for L5, in order to avoid any significant battery heating issue. This combo, for example, will take someone that might be interested (@fiacco) there (to 4.5V charging output): Ripcord AA923MS (from power full enough QC3.0 or similar port) + Adapter 2.1mm to 2.5mm + SW2305 Converter, A-port version of ZC855 (not quite sure/experimenting at the moment if PD coding goes under 5.0V).
@tomoqv, thanks for your observation!