Well, that depends on how confident you are in your charger and timer. I use both the Battery Minder and Battery Tender Jr's in my world and have confidence in them both. Failures could be costly however. I would not have the same confidence in my standard chargers, but does that mean that my confidence in the others is misplaced- I dunno. If I were leaving for the winter, I think the best piece of mind would be to leave it unplugged. The battery should be fine anyways. If your battery isn't nurtured to its fullest and it dies a year sooner- you aren't out much.

You are correct, battery chargers convert 115 volt AC to 12 volt DC, typically. If the charger supplies less than 1 amp, it would be called a "trickle charger." Lead/acid storage batteries contain a liquid electrolyte, that contains water and sulfuric acid. If the battery is very old, or has lost its electrolyte for some reason, it cannot be charged. Small amounts of hydrogen gas are released during the charging cycle, therefore this should be done in a ventilated area. I prefer a garage with the door wide open. Since the battery contains sulfuric acid, which is corrosive, it must be handled with extra care if there is any sign of leakage. I would put a leaking battery into a plastic tub, and take it to the recyclers. Small spills can be cleaned up with baking soda and water. The baking soda will react with any acid and neutralize the acid. Batteries do not benefit from overcharging. If the battery feels warm to the touch, it is likely fully charged, and time to stop. You should know the capacity of the battery in ampere-hours or ampere-minutes before you begin to charge. That number will guide you in knowing how long to charge. For instance, a 100 ampere-hour automotive battery being charged at 5 amps would take 20 hours to receive a full charge. That is, 5 amps times 20 hours equals 100 ampere hours.

My Schumaker charger is so old you'd need to do a carbon test to date it. It served honorably as the main charger for 10 years in my motorcycle shop and then went into private practice. I've come across quite a few dead chargers in the last 10 years and upon internal inspection I can tell you that in the case of most brands, including Schumaker, that the circuit boards are a lot thinner and of a much lower quality phenolic and not glass, even the wiring is of lower quality, and the soldering techniques (if I can call contemporary production soldering "technique") are of a poorer execution than in the past. Production QC today guarantees neither quality nor control. We are victims of the market screaming "cheaper" and we're getting exactly what (the majority of us) asked for so grin and bear it. Milacqua's favorite charger has it's share of complaints too. Storied names of the past on a box on the shelf today mean little to nothing cause the name is what is bought and paid for by some pacific rim conglomerate a la Zenith, Crosley, and such. Want a good charger? Cruise the thrift stores and flea markets and find an old, working Schumaker. clean it up and charge away and away and away and away... There is NO contemporary charger or maintainer that I would leave unattended plugged into an AC outlet, in my home or garage, connected to a battery for any period of time... except my old Schumaker. Out of sight... out of mind... out of luck sooner or later.

I was looking at getting one of these for camping. they sell them at local sporting goods stores like dicks and sports authority Clear Blue Hawaii Mana Solar Claw Turns Any Bag into Mobile Power Station if anyone has one I am curious to know how they are before I spend the money. Here is a link that might be useful: solar backpack charger