Mine has 3 settings, cant remember the voltage on each. When set to low I thought that's going to kill the battery before it kicks in but i didnt think about actual voltage drop when the compressor kicks in vrs the standing voltage. Might edge and go medium settingI’ve changed the euro lead for a UK one I had knocking about, on 240 volts it took about 15 minutes to go from 22 to 5, nice and cold. Need to do some 12 volt tests. Haven’t set the battery protection yet, as you say the instructions aren’t great