jumper cables - why plus to plus and minus to ground and not minus?

Question

Hello This is probably a layman question for professionals, but I would like to know, because I have noticed for a long time in the manuals of devices for starting cars, jumpers, a connection diagram in which the red cable connects plus to plus and the black one connects the minus pole of a...

riddyk · Answer

The fact that there is a certain resistance between the ground and the negative and this will limit the current when connecting the batteries.

mrmsim · Answer

This is probably also due to the fact that in many new cars the access to the battery is difficult (Mercedes Sprinter in the cabin under the floor, only the positive pole is located under the hood. Citroen C4 Picasso easy access to the plus, but to the minus without tools, no access) and not everyone must be familiar with it and know everything, which is why the instructions are probably adapted to today's realities. greetings

darkus1212 · Answer

This is stupid to me. After all, the plus and minus cables in a car have such a large cross-section and minimal length that voltage drops are negligible. Logically, when connecting the clamp to the steel element, it will have a worse contact than to the battery clamp. In addition, the clamp is quite large, the clamp needs to be expanded more, which means greater clamp pressure. I do not know why someone came up with it, since there is a greater drop on generally available starter cables with a cross-section of 2mm kw and steel clamps than on this piece of wire, which is about 35mm sq. Regards.

SlawekL · Answer

We assume that the recipient battery is discharged. Then, when connecting a functional donor battery, the recipient battery is rapidly charged, which is associated with gas release. Connecting / disconnecting the negative terminal always causes arcing which may ignite these gases.

Staszek49 · Answer

In my opinion, Sławek is right. Sparking occurs when making connections which may cause gases to explode and be spilled with acid. My brother had 2 such cases, but in a truck. In my opinion, first connect the pluses and then the minus clamp, e.g. to the engine block (recipient), i.e. away from the battery.

darkus1212 · Answer

I have a different opinion, the battery is gassing during the charging process, but not before, after connecting the charging, the gases must leave the battery and reach the terminals, so the sparking occurs before the gases are at the terminals, therefore, this theory is not true or so it seems.

tzok · Answer

Health and safety considerations - only and exclusively. The closing cable should be connected away from the battery. In case the battery is short-circuited or gassed strongly (in the donor car in which the engine is working or the engine has just been running).

przemek580 · Answer

I would also be inclined that it is rather done for security

Anonymous · Answer

And when you disconnect it, it also sparkles, in the meantime, when the battery heats up, it still blows out what's inside ... The gas caught fire, shot out, the housing broke, the electrolyte spilled out, it was not charging at that time, it became disconnected He might as well splash his face. Before you start to refute any theories, take a book and read what the smarter than you have already written. Then debunk ...

gukasar · Answer

Dear All,Unfortunately unaware of the above and through time pressure I grabbed the cables at short notice and connected plus to plus minus to minusRecipient Corolla 1.8H 2019Donor Fiat panda 2003So far all ok - due to the extensive electronics in my hybrid car; do I have anything to fear, what to check?

user64 · Answer

You don't have to worry about anything. However, you should also know that this is an emergency procedure, so get the car in good condition.

jumper cables - why plus to plus and minus to ground and not minus?

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