Originally posted by dbird:
or check to see what the voltage is to the battery when cranking, should be at least 9 volts, if you get a jump then you add 12 volts from the other car and your 3 or 4 volts and get 16 volts, then devide that by
two and you get 8 volts and that is why it is not starting or is starting it you have 6 volts and you put 12 plus volts on the jumper car that gives you 6 + 12 = 18 /2 =
9 volts and you can start the car.....





Sorry but this is not how it works.

Battery voltages do not sum or average when jumping. The voltage available is that of the higher battery, minus any current drop in the wiring.

"Those who cannot remember the past are condemned to repeat it" -George Santayana