is this a limitation on rb112 oder on the complete mips paltform ?
or why dont you just support simple ups monitoring
that would at least give 2 signal states “ups on battery” and “low battery”
but only “smart ups” are supported not the old ones wich only had a sort of “sigwatch” output
and there is no need to power a routerboard with at least a 700VA ups wich is the smalles APC product supporting serial smart protokol !!
tha produces only heat and wastes battery energy
i would be much mor usefull to have a small powersupply that has a little ups functionallity implemented (like “Mean Well AD-55A” ) an then monitor the voltage level or even use the error signal output from that device - which is logically up or down …