posted ago by bluewhiteandred ago by bluewhiteandred +9 / -1

So you connect red cables to the positive on each battery, red to red?

then black on the "alive" battery, to some neutral metal point on the "dead" car?

Do you do this then turn the "alive" car on, wait a minute then turn the "dead" car on?

Tips appreciated, thought this was a common issue to discuss

Comments (12)
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YouNeedVPN 4 points ago +4 / -0

Live car must be running before connection. You want that alternator cranking and producing power before connecting a power draw. If the live car is low on battery, connecting it to the dead car might be enough to mean you now have two dead cars.

I always did the negative connection first. I don't know the science, but ground coming first makes sense to me.

bluewhiteandred [S] 1 point ago +1 / -0

thanks for the input on if the car should be running or not

ok so possible ordering: black on grounding / piece of metal on dead car, then black on live car, then red on dead car, red on live car?

Removmudrace 2 points ago +2 / -0

Yes, and reverse the order when disconnecting, otherwise you get sparks.

YouNeedVPN 2 points ago +2 / -0


And thinking it over, the order of the first 3 don't matter, assuming that the last 2 are positive.

Connect the negative. Either order. You have grounded the cars together. This is 100% safe.

Connect one positive. As soon as you connect the positive, the other end of the cable could potentially arc to either of the cars. Just don't touch the red end to anything, and it's fine. Connecting to the dead car first is slightly safer simply because the battery has less current and therefor less arc on the off chance you were dumb enough to leave the other red clamp somewhere bad.

In short, be super careful with the red. That's the only source of danger, and the risk is essentially zero if you don't touch them to things.

ThurstonHowell3rd 4 points ago +4 / -0

I've watched a guy take a 6'piece of steel barbed wire and hold that to the positive terminals on both batteries with vice grip pliers then touch the two bumpers together and start the vehicle. Sassy!

BringTheCat789 4 points ago +4 / -0

The first thing you need to consider before jumping a car is: will the car benefit from a jump? A jump is only for a dead battery, not a bad battery, or any other issue. If the car is turning over, but not starting, a jump won't do it. If the car had started and then suddenly shut off, a jump won't do it. There are cases where jumping a car that has a problem that a jump won't solve can actually damage the car doing the jump.

Whenever someone asks me for a jump, I always ask them what issue they're experiencing before agreeing so I'm not putting my car at risk, or wasting our time. Essentially, if they say anything besides "I left my headlights on, and now my battery is dead," they probably won't benefit from a jump. Another case would be if their battery is old and has enough life left in it to keep the car running with the help of the alternator, but dies very quickly after the car is shut off. This is a dangerous game to play, though, as jumping bad batteries is risky business. If it's your own car, you may also need a jump if you let your car sit for a long period of time (avoid this by putting your car on a battery maintainer while it is in storage).

The correct way to jump a car is to start the car that's doing the jump, attach the red clamps to the positive terminals of each battery, then one black clamp to the negative terminal of the battery doing the jump (carefully controlling the other black clamp to prevent it from touching metal), then the other black clamp to somewhere with exposed and grounded metal on the car being jumped.

The idea behind that final connection not being on the negative battery terminal is that the final connection will spark as it is being made. Batteries release flammable gas, so you want to avoid these sparks being at the battery. However, finding a suitable ground to clamp the clamp to free of paint and rust is sometimes difficult, so I have always clamped to the negative terminal of both cars and have yet to have issues.

At this point, you want to wait with the car still running for a bit. The longer, the better. Make sure the cables don't get too hot (the thicker the cables, the better). After you waited a sufficient amount of time, try to start the car being jumped while it is still hooked up. If it starts, great. If it tries to start, but doesn't, you need to wait again, but this time for more time. If it doesn't even try to start, you need to reassess; one of your clamps may not be making a good connection. If you didn't see any sparks while making that final connection, this is likely the case. If you did see sparks, all the connections are fine and the car probably has an issue a jump won't solve.

Once both cars are started, remove the clamps in the reverse order you installed them in, taking care to control the removed clamps to prevent them from touching anything metal until they are all disconnected.

BadassRebel 3 points ago +3 / -0

I have never been able to get a dead car to start with the black cable attached to the frame on the dead battery's car.

I have ALWAYS had to connect all of the terminals to each other on both batteries. I always do red (live) to red (dead) and then black (live) to black (dead) while the cars are off. Then I start the live car and let it run, then the dead car always starts.

That said, be very careful NOT to touch any of the cable terminals to each other at any point.

funwithguitars 2 points ago +2 / -0

If attaching the ground to an unpainted piece of metal on the car doesn't work it's a sure sign that the battery terminals are dirty and need cleaning, and sometimes where the negative cable from the battery attaches to the engine block may be corroded and need cleaning. But all in all I attach mine right to the battery also because usually it is the cleanest ground under the hood. I clean all the battery terminals on every vehicle, mower, etc. every fall just b4 winter.

Nomoralcompass89 3 points ago +3 / -0

Yes there's some good comments in here. Also ill suggest, for the roughly 100 dollars, the lithium ion jump pack is good to have. Some of the kits can be used to charge cell phones, have plugs for laptops and such, and also a plug with 12v power that could be used in a dire situation to start a fire if survival was at stake.

bluewhiteandred [S] 1 point ago +1 / -0

interesting comment I had thought of buying one of those because I figured I could use it for other things most of the time and jump start a car if in need - got any specific ones you recommend?

Nomoralcompass89 2 points ago +2 / -0

I have the Matco badged one. Im pretty sure it was called the versa pro or something like that. It was pricier coming off the tool truck, but im sure its re-branded and made by someone else for less.

Its also really convenient for jump starting something you can always get a car to, like a lawn tractor dead in the shed. I keep it in my jeep with regular cables i have as a backup, right next to the back up 12v air compressor in case my on-board air fails. I'm big on redundancy.

Removmudrace 2 points ago +2 / -0

If a jump won’t do it, then try a trickle charger or worst case, de-crustifying the cells (which short circuits the battery). See