I gave this five stars because it has basically been my power supply / charger for my (usually) 23’ off grid camper. That’s hard use and it’s been doing it over a month now and doing it well.Once fall arrived with shortening sun hours and many cloudy days in a row my solar and batteries started struggling to keep up. I needed just enough extra power to keep the furnace running 24/7 without dragging down the batteries.It consumes very little power. I measured 1.94A at 120V (232W) while it was charging 14.9V at 9.4A (132W) for about 60% efficiency.Both the amps and the volts are adjustable with rotary knobs. This is convenient for many applications. If you were just holding a battery over winter, for example, you probably wouldn’t want to charge it to 13.8 volts, you’d just want to maintain the 12.8V full charge at say, 1A. This unit can do that!In my case, with the furnace or other items are consuming power, I want to charge at 13.2 or 13.4. If it’s cloudy I could charge at/to 14.4 to 14.6 and get some absorption charge (granted I get great solar charging on sunny days, so I don’t need a big battery charger. However, FYI 10A is too small to charge 300Ah or 600Ah of batteries. That’s not what this is made to do.)Right now it is set to 13.2V and 10A. As the battery reaches the set voltage the amps automatically reduce. The unit is displaying 13.2V and 1.2A and the fan speed is reduced.And yes, the fan is variable speed. If the unit is inactive because the battery has reached the set voltage the fan is stopped and the amps are zero. As the battery voltage declines, due to load or self discharge, the amps begin to rise and the fan begins to run. Turn the volts all the way up and the fan will go to max speed.The charger never has gotten hot, and the fan output has never felt warm. While the alligator clips and their wires also stay cool, I do have a complaint with the wire size- very thin and likely to be damaged. A 10ga wire would be a great improvement. Or at least something thicker and more flexible.Yes I’m using it for an unintended purpose but it’s been great. It’s living up to its price point.Great little charger!PS: all the poor reviews because people don’t know how to charge a battery? Pretty foolish to leave a bad review when the product is fine and the reviewers don’t know what they are doing. I’d buy again and recommend to others as well.Its not an automatic or smart charger as they claim. It's a fully manual charger and it works for what I needed it for. But to charge a large battery, i just dont see how you could get a quality charge with the chincy thin charging wire and clamps. The charger plug cord is very thin and too short. Have an extension cord ready.The charger cables are very thin and the clamps as cheap as they come. You can definitely find a better charger for the money from a reputable company for the money. I feel like this came from wish!I purchased this to use for rust removal using electrolysis. I read the ad and concluded the unit would be able to be used for this purpose. Tried hooking it up -- NO AMPERAGE.Instructions were a litle sketchy. Hard to know when it is chargingTripped the safety no matter what I tried. Returning and buying a better one.A review for the trickle battery charger. This little unit works good, simply connect it to a battery and it gives the easy to read numbers of watts and volts and plug it in and adjust the two dials for watts and to the desired amount for charging. There is an easy to read chart on top of the unit for detailed instructions.If this review provides the info you need before buying, please consider marking it "Helpful", as that's very helpful for reviewers!Pros:- charges all types of lead-acid batteries, including AGM, Gel, EFB batteries, regular wet batteries, etc.- can be used as a battery maintainer by just leaving it connected and plugged in at a low amperage.- overheat and overcharge protection appears to work, as I've left a battery connected for several days, both to maintain and to charge a nearly dead battery and there have been no issues. I have NOT cranked up the amps (or gone to a higher than rated voltage) to see if it will stop on its own though, because regardless of any built in precautions, the best way to prevent problems is to use a given device properly.- can also be used simply to test batteries, as the display will tell you the voltage as soon as you connect to a battery.- cords both for power and the jumper end are decently long at around 3 feet each, so gives you some reach to get it hooked up.- works as a booster pack as well obviously.Cons:- the whole thing feels lightweight and cheap, but I haven't had any issues with the actual functionality of it, so this is purely aesthetic so far.- the price (which is currently "unavailable", but when ordered was $99) is too high. You can get units that look similar enough to likely be made by the same manufacturer and all are just rebrands, and many of those other seemingly identical units are $50-$60, so why would I recommend this one? Pass.My battery was dead so i got this to charge my car's battery. First of all the instructions are not very clear. I did a Google of the voltage and amps to use just to make sire. After a free hours, However it was still not charged enough to gety car started. I did notice that even if i turn the job for amps up to 5A it only went up to about 2-3A. Maybe It'll work if I left it on longer? But still...not the most user friendly or efficient. I used another smart charger After for about 1-2 hrs and my car started. This confirmed my thought about this manual charger having a problem.This is a solid, manual charger. It comes in a very basic cardboard package. But the charging unit, itself, feels quite sturdy and well made. This unit has knobs to adjust but the voltage, from 12V-17.5, as well as the current, from 0A-10A. The digital screen shows the precise voltage and current that is selected. This is great for certain manual charging applications.The charger is quite versatile and can handle just about any lead acid, including car, SUV, truck, motorcycle marine, RV, as well as lawnmower-type batteries. The operation is simple and there are clear step-by-step instructions on a sticker affixed to the top of the charger. There are also examples of voltage and amp settings for common-type batteries. On the downside, the charger is a bit pricey compared to others, and it's also a bit more hands-on than automatic ones. However, for those who need a well-built manual charger, this one represents a solid choice.My unit arrived with a loose screw in the box. I later found that it was missing from the cooling fan. Not the end of the world, but it makes me wonder if there is a matching nut loose on the inside of the unit, waiting to short circuit something. I shook the device, and could not feel anything rattling.I think that the device is not packed well enough for transportation. It is sitting in a box with some molded styrofoam inserts. The device is not inside a plastic bag, so it was all covered in styrofoam crumble, and took a while to clear those. Styrofoam crumble clings very well.On the pro side, I like that the device allows adjusting both the voltage, and the current for the charging.The supplied manual is reasonably well written, and is easy to understand. I have a feeling that I know about all the modes of operation after reading it.The cooling fan is quite loud when the unit operates, even when there is no load.Overall, giving it 3 stars because of the issues I detailed above, and because it is not exactly cheap. I feel that, for the price, this device should come in better quality.4 easy steps for how to use this charger.1. Plug in AC power and turn the " ON" switch2. Set the charging voltage. In this step, read the manual carefully to decide what " V "is right for your battery.3. Easy to use, connect the red and black clamps to the car battery.4. set the charging current as needed.When the green light is on, it indicates the charge is charging normally.When the red light is on, it means errors. The errors could be short circuits, reverse polarity, overheating, etc. The charge will stop charging.After fully charged, it will actually use pulse current to maintain the battery and restore lost battery performance.It gives the battery a boost in winter when the battery is easy to run low or dead.Hope this review is helpful for your winter driving.