Can I jump start a 12 volt car battery from a 24 volt lorry battery?
Yes no problem HGV has two 12 volt batteries most are linked in series to give a 24 volt line voltage although some are linked in parallel to give only 12 volt but high current delivery.If its a normal 24 volt system connect black jump lead to one of the battery negatives and the positive to the SAME battery positive this will give you 12 volts which ever battery is used.Do not cross the batteries make sure you use only one.Use this system quite often to start reefer fridge engines which are 12 volt but coupled to a 24 volt rig.Reefers such as thermoking or carrier have very delicate ECUs and have never had a voltage spike problem with one.Always best to turn off the donor truck to protect its own ECUs from spikes as well
