The leads of the voltmeter are labeled that way to get a positive readout when you connect the positive lead to the positive terminal of the battery (and negative to negative). Digital Voltmeters will read negative voltage if connected backwards. Voltmeters with a needle, would have the current flowing in such a way that the needle would try to deflect 'below zero' because the needle windings are designed for the current to flow in one direction, to cause positive deflection of the needle.
Connect positive to positive post (red) on the battery and connect the negative to a place on the engine away from the battery.
When jumping two automotive batteries, connect the positive () cable to the positive terminal of the dead battery and the other end to the positive terminal of the live battery. Then, connect the negative (-) cable to the negative terminal of the live battery and the other end to a metal surface on the car with the dead battery, away from the battery.
If you connect the positive and the negative end of a battery directly with a cable, (1) you'll get dangerously high currents, and (2) the battery will quickly run out of energy. The battery itself might also get damaged, due to the high currents.
To safely jump a car when the positive terminal is red, follow these steps: Connect the red (positive) jumper cable to the positive terminal of the dead battery. Connect the other end of the red jumper cable to the positive terminal of the working battery. Connect the black (negative) jumper cable to the negative terminal of the working battery. Connect the other end of the black jumper cable to an unpainted metal surface on the car with the dead battery. Start the working car and let it run for a few minutes. Try starting the car with the dead battery.
Disconnect the cable from the LeSabre battery. Follow the route of the cable and disconnect the other end. Pull the cable out, then fit the new cable in the same direction. Connect the non battery end, then connect to the battery.
The positive end of a battery goes to the positive end of the terminal. In retro spec, the negative end of a battery goes to the negative end of the terminal.
Find a position for the battery then connect them together in parallel that is negative to negative positive to positive. That way you will still have 12 volts with larger capacity. Don't connect them in series that is positive to negative because you will end up with 24 Volts.
Best way would probably be to use a multimeter or voltmeter. Turn the meter on to volts DC and connect the probes to the battery terminals, if the voltage is shown as a negative, then switch the meter's probes around at the battery end so it shows the voltage as a positive reading on the meter. Mark the positive and negative terminals on the battery after this. Some car batteries have the negative terminal as the small post, but on some as the big post.
Connect the red cable to the dead battery's positive post and then connect the other end of the red cable to the good battery's postive post. Then connect one end of the black cable to the negative post of the good battery and the other end to a piece of unpainted metal in the engine compartment of the dead battery's car. Then wait 2-3 minutes and try to start the car.
To measure the voltage across a circuit component using a voltmeter, you would connect the voltmeter in parallel with the component. This means that you would connect one lead of the voltmeter to one end of the component and the other lead to the other end. This allows the voltmeter to measure the voltage difference between the two points, giving you the voltage across the component.
1. Connect one end of the positive cable to the "dead" or low battery positive post. 2. Connect the opposite end of the positive cable to the positive post of the battery being used for jump starting. 3. Connect one end of the negative cable to the negative post of the battery being used to jump start. 4. Connect the opposite end of the negative cable to a good ground on the "disabled" vehicle. Start the "good" vehicle and allow the "dead" battery to charge for 3-5 minutes. Start the "disabled" vehicle. If it doesn't start, allow to charge longer, then re-try. After the "disabled" vehcile starts, remove the cables in reverse order of connecting.
To jump start a car, first connect the red positive cable to the positive terminal of the dead battery, then connect the other end of the red cable to the positive terminal of the working battery. Next, connect the black negative cable to the negative terminal of the working battery, and finally connect the other end of the black cable to a metal surface on the car with the dead battery, away from the battery. Start the working car and let it run for a few minutes before attempting to start the dead car. The red cable should be connected first.