Bests & Worsts Reviews from Amazon

Somewhere, someone actually wanted to build a very good battery charger AND maintainer, and they actually did it. First: this is not a "jump start" high current charger. Second: if your battery needs a miracle, take it to church, because this wont fix it. Third: This is the best battery charger I have ever seen, especially for the price. I rarely write reviews. I am also equally rarely impressed with low cost made-in-China consumer goods. When I got this charger, I did not expect to be impressed. For fun I put a voltmeter and a current meter on it expecting to be unimpressed and to hate on it... To my shock and amazement, a pleasant surprise. They got this charger EXACTLY right. in short: In the video's above you can see the charger applying constant current of ~900mA then backing off and measuring voltage, all the way up to 14.5 volts-offo-the-charger, and then switching to 33mA of constant current. (note that if this were used in a car with large capacitors attached to the battery it may go in to the trickle charge mode a bit early, but this is not likely with most farm / atv / classic cars, and would certainly be avoided by pulling the battery terminal when you charge it) A few days ago, after throwing away my 3rd Harbor-Freight "trickle charger", (They last about 1 year then then seem to die, and their internals are is nothing more than a poorly regulated 14.5 volt constant voltage source with very little current) I started asking myself, "why don't you just go ahead and build your own charger... If i had the time, THIS charger would have been what I would have spent hundreds of hours perfecting. This charger is a smart charger that is actually smart. When you attach it to the battery, it measures the voltage on the battery, and if it is below 14.5 volts, this charger then applies about 0.9 Amps ( constant current mode, NOT dependent on battery voltage) for 10 seconds, then dis-connects the charge for 1 second, re-measures the battery voltage, and if it's disconnect-voltage is under 14.5 volts, it starts this cycle over and over again. This is an excellent way of truly top-off charging the battery, (1 Amp is not too shabby if you have more than a few hours). Once the 14.5 volt threshold has been crossed, the charger then goes in to a mode where it switches to constant-current of 35 Mili Amps, and stays in the 35MA mode until the next time that the charger is dis-connected from the battery. I know this is a bit technical for most non-battery nerds, but suffice to say, if you have a car / tractor / ATV that sits a lot more than you use it, this is the charger you want for it. It -WILL- charge a discharged battery fairly quickly (5-20 hours depending on battery size and how dead it is). It charges at a rate of 1-am-hour, so take your battery size and do the math.. It will not kill your battery with over voltage, and it will not kill your battery by completely disconnecting the charge from it, leaving it to slowly die offline. If I were to build a charger, this is what I would have come up with. Update: Left it charging over night, It is still testing the battery ever 10 seconds, and keeping 35mA going in to it. I also unplugged the charger, and measured to see if the charger itself would present a parasitic load on to the battery, which (in the case of the Harbor Freight charger) will kill the battery in the case of a long-term power outage. GOOD NEWS: this charger has ZERO parasitic load if the main power fails, so it will not kill a good battery in the case of long-term power outages. Again, this is an excellent charger.