Deltran Battery Tender 12-Volt 800 milliamp Waterproof Battery ChargerThe Battery Tender Waterproof Tender operates in essentially 3 stages. It first initiates an absorption charge that attempts to charge your battery to 14.5 VDC at up to 0.8A (or 800mA). This bit of information was not readily advertised, so I was concerned when I heard my battery making gurgling noises while the LED was "amber" for the past 8 hours. This battery was only 2 years old with less than 5000 miles and had been maintained since day 1, so I was sure it wasn't a problem with the battery. It turns out that it was nothing to be concerned about since this charger was designed to be used for long-term storage of batteries.My previous charger, a Black & Decker / Vector 2A "smart" automatic maintainer tried to keep my battery voltage at 14.75 VDC at 2A for over 24 hours. Needless to say, I was concerned when I saw this happening with a brand new Battery Tender. I dug around on their website and discovered a PDF that indicated the Tender would try to reach 14.5 VDC for the absorption phase, at which point it would switch to a trickling charge and finally the maintenance charge. I logged all of the readings and confirmed that once the battery reached 14.4-14.5 VDC, it would start to trickle down finally remaining at about 13.12-13.22 VDC @ 20-100 mA. A modern car's parasitic draw is about 10-50 mA, so the maintenance charge is to compensate for the parasitic draw and for self-discharging of the battery. I discovered the Tender does a much better job at a maintenance charge because I have yet to see the Tender go into the Amber-LED mode, whereas my Vector/B&D; occasionally switches back and forth even on a fully charged battery. I logged some data from the Vector/B&D; and discovered that once the LED is green, it provides NO current to the battery. In essence, the Vector/B&D; just shuts off once it reaches 14.5 VDC - which is not as useful as providing an actual maintenance charge. The Battery Tender wins. Quite a few people have commented that their Sears "smart/automatic" maintainer and other brands constantly switch between the Green and Amber modes. I suspect those chargers are doing the same thing as the Vector/B&D.; They just shut off when the battery is "charged", which is not very good for the battery. It needs to hold a maintenance charge to prevent sulfation.The Tender Waterproof is fully encapsulated with a thermally conductive potting material. This makes the unit quite heavy for such a small device. It uses a quick-disconnect 2-terminal fitting that is commonly used for battery chargers/maintainers. It comes with ring terminals or large battery clamps all fused with a 7.5A ATC fuse. I made my own wiring harness with smaller alligator clips since I don't have room under the hood for large clamps, and I do not want to permanently install a set of ring terminals that can short out or cause other problems in the long-run.Pros: Battery Tender has an excellent reputation for making reliable chargers. The Waterproof unit is quite durable and is insulated from shock, water, corrosion, extreme temperatures and other environmental variables.Cons: At 800mA max current capacity, this charger will work rather slowly for 50Ah or larger capacity batteries, so expect 10-12 hours upon hooking it up to a battery before the LED turns green. The benefit of this is that it prevents boiling the battery or generating a lot of heat due to excessive current.Overall: If you're using the charger in an environment subject to cold or hot temperature swings with plenty of moisture, such as in a detached garage for your motorcycle, boat, stored vehicle, or even a daily driver, I highly recommend the Waterproof unit over the Tender Jr or Tender Plus.UPDATE:I decided to purchase an additional Battery Tender Waterproof because I needed another charger for my daily driver and because I experienced no problems with the first unit.