Review on 🔋 NOCO GENIUS2: Advanced 2-Amp Smart Charger for 6V and 12V Batteries - Battery Charger, Maintainer, Trickle Charger, Desulfator. Includes Temperature Compensation. by Michael Keitt

I'll get into how this charger works in a moment, but first let me say that I would probably have returned it as faulty if other reviewers hadn't warned me about what to expect as obviously no other people did who are buying it for the first time and it is entirely the fault of the manufacturer who sends it with instructions written by people who know the product inside out but compared to why and how most people use it buy it couldn't be any less helpful, so my rating is only 3 out of 5. Let's start with the basics; Despite all its advanced features, this is only a 2 amp charger. The instructions describe a general formula for calculating the charge time depending on the capacity of the battery and most people who buy it because of its low price have no idea what is under ideal conditions it literally takes a couple of days to get one typical 12V AGM battery. While the battery is being returned during desulphation, the gauge will alternate between charging and failing, meaning you'll have to start and restart it as long as it continues to charge, and it's not mentioned anywhere to the benefit of most people using it for the first time try - so here it is first. The second thing the instructions don't make clear is how to access "Boost Mode". ; The instructions say to hold down the mode button for 5 seconds (the video says 7 but hey why nitpick?) and try as hard as I can I couldn't get it to work which seems very important, when the battery was completely dead, like mine was at the time, until I accidentally tried it before plugging it into the battery, and hell if it didn't work then - note - to use "forced mode". , the charger needs to be plugged into an outlet but NOT plugged into a battery first and judging by other reviews there are a lot of people who never get it right and again you won't find this in the manual so I can't recommend this product not giving it the highest rating for all of the reasons above, although technically it does what it says on the tin - yes it does. So you wanted to know how this thing actually works if I really understand how it works? In short - once you get past the instructions, or lack thereof, this is simply an amazing product for the price! How amazing? My 90 amp 12 volt AGM battery was completely dead and sulphated when I plugged it in Tuesday night and it initially only charged for a couple of hours before giving up due to a bad battery/charge indicator not holding. -- but every time I plugged it back in it could take a little longer, and I was hoping it would finally turn the corner after a 12-hour run, but it still couldn't hold a charge until I went on Wednesday found a way to get it working in "boost mode" (see above) and sometime on friday night it finally passed the first bar of the gauge and on saturday night it passed the orange bar and as of this writing, is on Sunday evening the green flashing gauge - it's been over 100 hours exactly as the formulas show but the battery seems to be on the way to full recovery - YES! If only they could fix the documentation now.