Which Car Battery Charger Brand Wins?

powered up, on standby, not charging, 0W energy use

powered on, idle draw ~0.5W, not charging at 1V starting point

idle draw ~0.5W when plugged in unconnected; once connected does not recognize the battery, even in pulse repair mode

idle, still 0W once connected, did not detect the battery initially

idle draw ~0.72W; no override or force-charge option, so it could not begin charging the fully dead battery

display draws about 0.5W but no indicator lights show power-on; not charging

powered on with about 0.5W draw; battery was too dead for it to begin charging initially

idle draw about 1.18W; not able to charge the fully dead battery from a cold start

idle draw about 1.3W; not able to charge the fully dead battery

set up like the Genius 1, able to charge the fully dead battery using force-charge mode

powered up but unable to detect or charge the fully dead battery

unable to detect or charge the fully dead battery, same limitation as Battery Tender

began charging around 10V, peaked at around 27W (just over 2A, matches its 2A rating)

began charging around 8.46V, peaked at just under 26W (just over 2A versus its claimed 1.5A rating)

began charging at 1V, peaked around 91W (about 7.6A, better than its 6A rating)

came to life around 2.5V (about 10W, under 1A) early on; stopped charging at just over 7V because it had defaulted to 6V mode; required a manual switch to 12V, after which it rose to about 22.6W

started charging around 3V; the charger's own amp display appeared inaccurate versus measured energy use; peaked at about 86W (about 6A, matching its claimed 6A rating even though its own display read closer to 3.5A)

slow to start, began charging around 9V, peaked at almost 18W (about 1.5A, matches its rated 1.5A)

began charging just over 3V as advertised; stopped unexpectedly around 9V and needed a disconnect/reconnect to resume; peaked just over 60W (about 5A versus its claimed 4A rating)

began near 1V, stayed under 10W until 11V then jumped to about 78W peak (about 6.5A versus its rated 5A)

began near 1V, single digits until 7V then rose to about 79W peak (about 6.6A versus its rated 5A)

active indicator near 1V, single digits until 7V, peaked at about 72W (about 6A versus its rated 5A)

slower to start than Hulkman, Eco-Worthy, and NOCO, kicked in around 3V, under 10W until 10V, peaked about 63W (about 5.25A versus its rated 4A)

most ambitious at low voltage of all chargers tested, over 20W at 3V, over 50W at 10V, peaked about 65W (about 5.4A versus its rated 4.3A)

hottest of all 13 chargers tested

running warm

kept cool by an internal fan

kept cool by an internal fan

warm

coolest of all 13 chargers, credited to its internal fan

warm

overcharging above 15V (15.1V per closing summary), continues supplying current past full, no true float mode

shows full at 14.1V but still supplying about 2.4W, ramps up output when voltage drops

shows full at 13.9V but still delivering about 7W, adds more current when voltage drops

shows full at 14.8V, still supplying charge; narrator calls 14.8V clearly overcharged

showed full with less than 1W draw, reacted properly to a forced voltage drop

shows full at 13.9V, still supplying about 6W, reacted properly to voltage drop

showed full at 13.3V, cycled back on properly once the voltage drop began

should be finished around 13.6 to 13.8V but kept supplying current; still reacted properly to a forced voltage drop

supplying about 2W at 13.6V, reacted properly to voltage drop

finished around 13.3V, topped off, reacted properly to voltage drop

completed at 13.1V, on target, reacted well to voltage drop

finished at 13V with about 0.5W draw, increased output properly on voltage drop

created a lot of sparks, one of 4 brands that sparked

did a great job avoiding sparks

generated a lot of sparks, one of 4 brands that sparked

did a great job suppressing sparks

did a great job, spark-free

did a great job suppressing sparks

produces sparks, one of 4 brands that sparked

performed just as well as Genius 1, no sparks

performed well, no sparks

delivered on its spark-free claim, no sparks