Battery maintainer and sensitive electronics

[f355spider]

Someone posted in another thread that this inexpensive maintainer on Amazon floats at a nice 13.6vt consistently. I believe the person posted he owned three of them?
https://www.amazon.com/dp/B07TDWJ9V...olid=1HQINTSOFSKRQ&psc=1&ref_=lv_ov_lig_dp_it