"y_p_w" <y_p_w@hotmail.com> wrote in message
news:33f33c40-0b42-4ed5-a909-ace5e9cfac6d@d7g2000prl.googlegroups.com...
> 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.

If it's a manual charger then you have to watch it. If it's a sealed
battery then you can't check the specific gravity so it's more difficult to
determine when the battery is fully charged. Personally I like to use a
Smart Charger and periodically use the Desulfate and Equalize features,
especially if one or two cells are a bit lower than the others. If the
Smart Charger shuts off and I don't think it's quite done yet (all cells not
equal) then I'll use a 1/2-1 amp charger for an extended period of time,
checking it regularly. But I don't think, under most circumstances, that
you can properly recharge a car battery with that low of a charge rate if
it's considerably discharged.