Won't hurt anything. Connecting the jumper box in to your truck with the 6 volt battery still in it will 'throttle back' the 12 volts coming out of the jumper box. Just disconnect it after the jump.

This is how battery chargers work anyway. 12 volt battery chargers put out anywhere from 18-24 volts unloaded, and 6 volt battery chargers can put out up to 12 volts. Connect it to your battery and the voltage is then normalized.


1960 GMC Panel w/ 305 V6, 4 Speed TV Repair Van "The Monitor Lizard"
1961 Chevy Apache 20 283, 4 Speed, Hydrovac
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