I'm a fan of posts # 3, 4, 6, & 9. I guess that makes me " x 5 "
However, In weak moments I bought a Schumacher 1562 (6-12V, 1.5A, charge/maintain),
A CTEK 3300 (12V, 0.8A/3.3A)
A BatteryMINDer Plus 12117 (12V, 1.3A)
and have used a neighbors BatteryTender.
I was experimenting. Experiments yielded nothing of value to me.
I have no opinion on any of them, and would never consider leaving any of them on, un-attended. I'm especially leary of leaving the Schumacher unattended, because one of the fellows on the 'barn' once posted that his failed, causing sparks within the 'box', and had the potential for a fire???
I'm also one of those that has had good life from seldom-used collector-car batteries, I've had two that have lasted 14 and 16 years, with almost NO maintenance.
Over the winter, when I think of it, I put a trickle charge on, never for more than an 8-hour period, maybe once at the end of winter. When I retire for the night, the charger(s) are unplugged. Just opinion.
Forgot... I don't leave batteries hooked up. One battery post is disconnected, except when I'm using the car. For the 'wife's car', or any modern car that sucks the battery down (due to alternators, security systems, radios, etc), I have the battery disconnected when it is left unattended for any length of time, like vacation, over winter, etc. IMO, it's better for the battery, and removes the possibility of something going 'wrong' while I'm away.