Review on Smart Battery Charger/Maintainer with Engine Start - 2/10/25A, 12V | Fully Automatic | Cable Clamps by Bob Walters

Reviewers who think this charger won't work in recovery mode on a truly dead battery should take note. In order for this charger to initiate a charge sequence, whether normal charge or recovery, it must detect a minimum voltage level. If the voltage is too low, it will not light up. It's most likely in recovery mode if you have a really deep battery. The trick to getting it to fire is to connect a known good battery in parallel, connect the charger (I connected the charging terminals to the terminals on the jumper wires) and start the normal 2 amp charging sequence. The charger sees enough voltage from a healthy battery to begin charging; and it charges both batteries. Leave it like that for a few hours until the empty battery is recharged. Now disconnect the good battery with the jumper, attach the charging clamps to the dead battery and start the recovery charge. The charger must have sufficient voltage to function. If not, charge the jumper for a few hours and try again. Not all dead batteries can be recovered, you just have to try. Old school chargers didn't have that kind of voltage sensor, you plugged them in and they output current. If you have an old charger, you can use it to charge a dead battery for a while, get some voltage (if it's charging) and then try to restore the charge on that charger. Unfortunately I needed this charger three times. in the first two weeks of its existence. A friend had his car battery burn out and I was able to restore it as above. My own battery died leaving the door open. I was in a hurry to get to work, the car wouldn't start! I used the jump starter, started the car and got to work. I installed a new battery in the car and found at the auto parts store that it was not fully charged. I fully charged overnight. I got my money's worth and in two weeks some more!