With a caveat to the effect that not all batteries, or indeed, tenders, are the same in terms of quality and function; I ve had bike batteries on tenders for years without issue !
I also use solar 'top-up"panels. I have quite a few batteries that need caring for, especially during the winter months, but also because some vehicles drain the cells, and this is an affordable solution. It is the only option for people without power.... An isolator switch in conjunction with a solar panel throughout the cold, dark winter months is, I believe, probably all you really need for a battery that is in good condition to start with....
I also use solar 'top-up"panels. I have quite a few batteries that need caring for, especially during the winter months, but also because some vehicles drain the cells, and this is an affordable solution. It is the only option for people without power.... An isolator switch in conjunction with a solar panel throughout the cold, dark winter months is, I believe, probably all you really need for a battery that is in good condition to start with....