Quote:

What should be the maximum voltage draw be between the negative cable and negative post?



Voltage is a measurement of potential work to be done , there is no draw associated with it.

think voltage as water pressure

think of current(amps) as the volume of water

think of the size of a pipe as the resistance in a circuit

if you have a steady water pressure (volts) and a 1/2" pipe(resistance) there will be a certain flow (amps) rate.

if you increase the pressure (voltage) but keep the pipe (resistance) the same size you will have more flow (amps)

if you keep the pressure(voltage) the same but increase the pipe size (resistance) you will also get more flow (amps)

I think you were asking how many volts should you read between the cable and the post when disconnected. and that question can only be answered by having a resistance reading from the positive cable to the negative cable.