That Black & Decker Charger that Dave linked seems like an interesting one. It does not appear to offer some of the advanced features of the BatteryMinder units, but the 6 Amp model is a couple classes higher in the waterproof rating: Black and Decker unit is rated IP67 = submersion up to 1 meter deep for 1 minute, vs BatteryMinder IP65 = water jet from any direction. (IP 65 is relatively low pressure: more than a splash, but probably could overcome it with a spray nozzle on your garden hose if you were persistent.)
For the B&D units, you have to step up to the 15 Amp rated one before you get "battery reconditioning" (They don't explain it, but this is could be pulse desulfation, like what BatteryMinder has, though it's possible it is the less sophisticated "equalization charge".) However, that unit is no longer rated as waterproof.
That 6A B&D one nicely filled a recent gap in my charger lineup.
I have an original VDC 1.5A desulphating wall-wart like a number have people have posted about. Running as we speak, on a MC battery. Have had
many years of great service from it.
A Ctek 3300 that I have 6+ years of constant service out of. Started acting up... per a few TBN posts, it may be nothing more than the mode selector switch, or a low-spec cap..... Liked the unit, but haven't cracked it open yet.... my old-vehicle MustDo projects keep taking precedence.
I have an olde-school (analog/linear, big TX core) 6A charger, that I paid something like $16 for, new, too many years ago.... Still works fine, and is my goto one for lifting a battery out of the weeds.... it just gets to work charging from the getgo, rather than the
How Am I Feeling Today/Snowflake moods that some modern micro-controller based units get into.... Someone could offer me $200USD for that one, and I wouldn't take the offer.....
On a 1200km trip, I thought I had an alternator acting up, so bought a 15amp Schumacher charger. Multi-chemistry unit, with select-able output limits, % complete info..... good capable charger, but has an annoying-from-new fan noise...... the fan works fine, I just find it annoyingly shrill..... Out of what I have at present, likely my best AGM charger.
I'm fairly careful with my chargers, but "stuff" happens..... I've grown to appreciate simple and rugged case designs, and came to rely on the waterproof aspects of that Ctek. I still shelter an outside charger as best I can, but found that I was more likely to
Get On With Charging Something, even if the weather looked dodgey, when the Ctek was up and running.....
Until you get into more expensive cables (not in lower or mid-tier consumer products usually), modern (post ROHS) cables have more trouble with very low temperatures. Some people had trouble with that 6A B&D, with the cables cracking...... these basic cables are stiff to begin with, if you wrap 'em tightly around the unit at -40..... you get what you get....... a version of the olde joke...... "Doc, it hurts when I do this___________".........
When you begin collecting tools, you might think "
Why would I need more than one hammer ? "........ Chargers are like hammers, you can make do with one, but often it's nice to have a choice to work with....... I'm glad to be back to having a simple/rugged/waterproof "hammer" in my range of entropy-fighting weapons

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Rgds, D.