7 replies to this topic

[croc7]

How would one jump start a positive ground car with a dead battery using a negative ground car's battery?

[Clip]

How would one jump start a positive ground car with a dead battery using a negative ground car's battery?

If this is confusing for you just connect both cars directly to their batteries. Negative goes to negative, positive to positive. 

Edited by Clip, 23 June 2020 - 07:02 AM.

[slidehammer]

The only thing you would have to watch out for is to make sure nothing metal on the 2 body shells touch each other as one is negative and one positive. So provided you do as above (just connect the 2 batteries) it will be fine.

[croc7]

 

How would one jump start a positive ground car with a dead battery using a negative ground car's battery?

If this is confusing for you just connect both cars directly to their batteries. Negative goes to negative, positive to positive. 

 

It is confusing to me.  So it would be; Negative terminal on dead battery on the positive ground car, connected to the negative terminal terminal on the negative ground car (power).  And the positive terminal of the dead battery on the positive ground car to a point on the chassis of the negative ground car (ground)?

Edited by croc7, 24 June 2020 - 02:44 AM.

[retired]

It is confusing to me.  So it would be; Negative terminal on dead battery on the positive ground car, connected to the negative terminal terminal on the negative ground car (power).  And the positive terminal of the dead battery on the positive ground car to a point on the chassis of the negative ground car (ground)?

 

No, because the chassis of the negative ground car is negative, not positive, and is not power.....

 

Just ignore the chassis of each/either, just make sure they are not touching each other (as mentioned earlier) and just connect the battery terminals, positive to positive, and negative to negative.

 

Connecting direct to the terminals is better anyway (less voltage drop) and ideally connect to the dead battery last as there will be a small spark and the dead battery is least likely to have any hydrogen around it (unless you have recently been trying to charge it with a normal charger).

[GraemeC]

 

It is confusing to me.  So it would be; Negative terminal on dead battery on the positive ground car, connected to the negative terminal terminal on the negative ground car (power).  And the positive terminal of the dead battery on the positive ground car to a point on the chassis of the negative ground car (ground)?

 

Connecting direct to the terminals is better anyway (less voltage drop) and ideally connect to the dead battery last as there will be a small spark and the dead battery is least likely to have any hydrogen around it (unless you have recently been trying to charge it with a normal charger).

 

 

Technically not true - the weak battery is most likely to give off hydrogen, especially once the leads are connected and/or the car started.  For this reason I would NOT connect to moth terminals of the weak battery as there is an increased chance of explosion.

In this scenario I would connect in the following order:

Black lead to -ve terminal of good car

Black lead to -ve terminal of flat car 

Red lead to +ve terminal of good car (make sure the other end isn't touching anything)

Red lead to chassis or ground point of flat car (personally, if the leads are long enough I would connect it to the engine block where the earth strap is - somewhere away from the battery)

[Cooperman]

Make sure the vehicles are 'socially distanced'  .

[retired]

 

Technically not true - the weak battery is most likely to give off hydrogen, especially once the leads are connected and/or the car started.  For this reason I would NOT connect to moth terminals of the weak battery as there is an increased chance of explosion.

 

Incorrect I'm afraid.

 

The dead battery will give off no hydrogen unless the OP has been trying to charge it.

 

If it is dead/flat there will be no hydrogen.

 

But a live/working battery will always have some around it.

 

Basic physics really.

 

Always make the last connection to the dead battery (unless you have recently been trying to charge it)