So here's the deal. The car is a Honda Civic with a group 51 battery
(Kirkland Signature from Costco if that helps). Every once in a while
the battery is heavily drained because a light (map light or headlamp)
was left on. I do find it annoying that there is no headlight-on
warning chime or auto-off. Sometimes it starts and sometimes it needs
a jump; a portable jump starter always does the trick. The car itself
is driven maybe a few times a month for short distances along with the
occasional long trip.

So I got a simple Schumacher Electric 1 amp, 12 V trickle charger -
the kind with thin wires and light-duty clamps coming out of a wall-
wart. It's labeled as a "manual charger" and the box/directions state
that it's suitable for charging motorcycle and other small batteries,
or for keeping auto batteries warm. I wasn't sure if I could justify
getting anything more expensive like a higher output charger or maybe
even a float charger/maintainer with a charge sensing mechanism.

So I'm wondering how safe this is with a group 51 battery, which is on
the small side for auto batteries? I realize that it's not likely to
fully charge up a depleted battery unless it's on for days at a time.
How safe is a 1 amp charge if uncontrolled like a float charger? I've
heard some concerns that it could potentially overcharge - that maybe .
25 amp is about the limit for safe trickle charging. I've heard other
comments that it's effectively a trickle charge that could safely be
left on a fully charged car battery for days if not indefinitely.