Red on dead, and the black clamp nobody gets right

Quick answer: Red clamp on the dead battery's positive. Red on the good battery's positive. Black on the good battery's negative. Last black on bare, unpainted metal on the dead car, away from the battery. Take them off in exactly the reverse order.

That's the whole job. Four clamps, about ten minutes. A decent set of cables costs less than one tow.

The parking lot scene

It's 6:40 on a January evening at the grocery store. It's eighteen degrees. You turn the key and get a fast click-click-click and dashboard lights that flicker like they're embarrassed. The ice cream in the back seat is on a clock.

A kind man two spots over has cables in his trunk. He pops both hoods, holds up a black clamp, and pauses. He's about to put it on your dead battery's negative post. Most people do. It usually works, and that's exactly why the habit never dies.

If you know the order, you're the one who says, "Let's put that one on the engine block." And then it's handled. You can thank him properly, and you'll learn something about the guy who stops in the cold and doesn't make you feel small for needing a hand. What a man does when it costs him something tells you plenty.

Why the last clamp goes on metal

A battery that's been charging or straining can give off hydrogen gas. Hydrogen and a spark don't mix. And the final connection in the circuit is the one that sparks.

So you make that final connection somewhere away from the battery. Use a bare bolt, a bracket or an unpainted part of the engine, ideally a foot or more from the battery. Your car's frame is wired to the battery's negative side, so the circuit still closes. The spark just happens where it can't hurt anything.

Clamping the dead battery's negative post directly works most days. Most days isn't the standard you want with your face eighteen inches from a battery.

Before you touch a clamp

Get this part right and the rest is mechanical.

• Look at the dead battery first. Cracked case, leaking fluid, a rotten-egg smell, or sides that bulge out? Stop. Don't jump it. A battery that froze solid can split, and jumping a frozen battery is a bad idea. Call for a tow.
• Park the cars close but not touching. Nose to nose or side by side. Both in park (or in gear for a manual), parking brakes on, both engines off.
• Turn everything off in the dead car. Headlights, heater fan, radio, phone charger. You want every amp going to the starter.
• Find the terminals. Positive is marked +, usually has a red cover, and the post is slightly fatter. Negative is marked −. White or green crust on the terminals? Wipe it off with a rag (gloves on, and keep it away from your eyes). Clamps can't bite through corrosion.
• Tie back your hair and lose the scarf. The cooling fan on some cars can kick on even with the engine off.
• Check the owner's manual if the battery's hiding. Plenty of cars keep the battery in the trunk or under a seat and give you remote jump posts under the hood instead. Use those. And if either car is a hybrid or an electric, check its manual too. Many makers say not to use one as the donor car.

The four connections, in order

1. Red clamp to the positive post on the dead battery. Wiggle it until the teeth actually bite metal.
2. The other red clamp to the positive post on the good battery.
3. Black clamp to the negative post on the good battery.
4. The last black clamp to bare metal on the dead car, away from the battery.

The rhyme that sticks: red on dead, red on donor, black on donor, black on metal.

From the moment the first clamp goes on, keep the loose ends apart. Two clamps touching each other while the other end is attached to a live battery will spark, weld themselves a little, and scare you badly. Hold the free pair in separate hands or lay them on the ground apart.

Starting it

Start the donor car. Let it run for three to five minutes. In bitter cold, give it longer. The good battery's trickling charge into yours, and patience here saves you a second round.

Then try the dead car. Crank for no more than about five to ten seconds. If it doesn't catch, wait a couple of minutes and try again. Cranking nonstop overheats the starter and drains whatever charge you've built.

What the car's telling you:

• Rapid clicking: still not enough charge. Wait longer with the donor running.
• Nothing at all, not even dash lights: usually a bad connection. Recheck all four clamps for real metal-to-metal contact.
• It starts, then dies within a minute or two: the battery may be fine and the alternator may not be charging it. That's a mechanic visit, not another jump.
• Slow, groaning crank that gets there: congratulations. Now go do the next part.

Taking the cables off

Exact reverse order, with both engines running.

1. Black off the bare metal on the formerly dead car.
2. Black off the donor's negative.
3. Red off the donor's positive.
4. Red off your positive.

Don't let the clamps touch each other or anything metal while you're doing it. Then close both hoods, coil the cables, and hand the donor something warm or at least a sincere thank-you. If a friend lent you the cables, bring them back coiled neater than you got them.

After it starts

Drive. Don't idle in the parking lot. Twenty to thirty minutes of real driving gives the alternator a fair shot at recharging the battery. Idling barely does anything.

Then get the battery tested. AutoZone, O'Reilly and Advance Auto Parts will test it for free, and it takes minutes. A battery that died once for no obvious reason (no headlights left on, no dome light) is warning you. Most batteries last somewhere around three to five years. Summer heat does the damage. The first cold morning just reveals it.

The cables, or a pack

The cables in most trunks are a joke: thin wire, short reach, clamps that couldn't bite an apple. When you buy, look at two numbers.

• Gauge. Lower is thicker. Get 4-gauge or 6-gauge. Skip 8 and 10. Thin cables heat up and deliver less.
• Length. At least 16 feet, and 20 is better. You won't always get to park nose to nose, especially in a garage or on a shoulder.

The other option is a portable lithium jump starter, about the size of a hardback book. You clamp it to your own battery and you don't need a second car or a second person. The NOCO Boost line is the one you'll see everywhere, and it's earned that.

The pack wins if you drive alone at night, park in garages, or live somewhere a stranger with cables isn't a sure thing. It has one real downside. It has to be charged to do anything, so put a reminder on your calendar to top it off every few months. A dead jump pack is an expensive paperweight.

What we'd buy: a 4-gauge, 20-foot set of cables for the truck or the family car, plus a lithium pack from a known brand for whichever car does the most solo driving.

What we'd skip: the cheap thin-wire sets sold near the register, and no-name packs bragging about huge "peak amp" numbers. Peak amps are mostly a marketing number. Buy the brand, not the sticker.

Teach it before you need it

Do it once on a Saturday in your own driveway, in daylight, with no ice cream melting. Let your teenager do the clamps while you call out the order. The first real dead battery should feel like the second time, not the first.

And when you're the one parked two spots over and somebody's hood is up, you'll know which clamp goes on the metal.