Red goes on the positive (+) terminal on both cars; black goes on the donor’s negative (−) post and a clean metal ground on the dead car.
Quick answer and why polarity matters
Short version: red means positive. The red jumper cable attaches to the battery post marked with a plus sign and often protected by a red cap. Black means negative. That clamp goes to the negative post on the helper car, and for the dead car it should land on a clean, unpainted metal point away from the battery. This prevents sparks close to venting gas and protects you and the car.
Polarity is not a style choice. Reversing the red and black clamps can blow fuses, damage control modules, and send a shower of sparks you do not want. Most cars label battery posts clearly, and many place a red protective cap over the positive side. If the posts sit on opposite sides or the battery hides under a seat or trim, follow the symbols, not the side.
Battery terminals at a glance
The table below gives you a fast map of what each post, color, and symbol means, plus where to attach each clamp during a jump-start.
| Item | Markings or color | What to do |
|---|---|---|
| Positive battery post | “+” symbol, red cap, thicker cable | Attach the red clamp here on both cars |
| Negative battery post | “−” symbol, black cap or bare lead | Attach the black clamp here on the helper car only |
| Engine or chassis ground | Unpainted metal, bracket, or ground stud | Attach the last black clamp here on the dead car |
| Remote positive terminal | Red cap with “+” under the hood | Use this point for the red clamp if battery is buried |
| Remote ground point | Metal stud marked “−” or ground icon | Use this point for the last black clamp |
| Top-post battery | Two round posts on top | Clamp straight onto the posts as labeled |
| Side-post battery | Studs on the side of the case | Use side-post adapters or the remote posts |
| Start-stop system | AGM battery, extra cables | Use the under-hood posts; avoid direct battery access |
| Hybrid or EV | 12-volt battery plus high-voltage system | Jump only the 12-volt system; never touch orange cables |
| Portable jump pack | Red and black leads | Connect just like cables, following the same order |
You can also double-check the positive post by tracing the cable: it feeds the fuse box and starter. The negative cable bolts to the body or engine. If corrosion hides the markings, clean just enough to see the symbols with a dry rag or a dedicated brush, then connect.
For a clear walk-through with diagrams, see this AAA guide to jump-starting. It shows the exact posts to use, plus the remote jump points many modern cars include.
Step-by-step: connecting jumper cables safely
Set both cars in park or neutral, set the parking brakes, and switch off accessories. Position the cars so the cables reach without stretching, and keep the vehicles from touching. Open the hoods and open the battery post caps or remote terminals.
- Red to dead: place the red clamp on the dead car’s positive (+) post.
- Red to donor: place the other red clamp on the helper car’s positive (+) post.
- Black to donor: place a black clamp on the helper car’s negative (−) post.
- Black to ground: place the last black clamp on a solid, unpainted metal point on the dead car, away from the battery and moving parts.
- Start the helper car and let it idle for a few minutes; a gentle throttle blip can add charging current.
- Try starting the dead car. If it does not start, wait two minutes and try again.
- Once the engine runs, leave both engines idling for five to ten minutes to build charge.
- Remove the cables in reverse order: black from ground, black from donor negative, red from dead positive, red from donor positive.
That order matters because the last clamp to connect and the first to remove is the one most likely to spark. Placing that one on a grounded metal point keeps any spark away from the battery. This practice is backed by workplace rules that call for the ground lead to connect away from the battery itself, reducing the chance of igniting gas vented during charging. For a plain-language refresher, see the federal text here: OSHA 1917.157, which specifies connecting the ground lead away from the battery.
Which side gets the red clamp when jump-starting?
The red clamp always goes to positive, whether that post sits on the left, right, front, or rear of the battery. Batteries are not laid out the same in every car. Some place the positive post toward the windshield, others toward the bumper, and some tuck the battery out of sight. Go by the “+” mark and the red cap, not by the side. If you find only a red cap and a separate ground stud under the hood, those are remote jump points that replace direct battery access.
Where the red jumper cable goes on a car battery
When you see a battery with two exposed posts, clamp the red lead straight to the post with the plus sign. When the battery uses side posts, use an adapter or the remote posts under the hood to get a firm bite. On vehicles with start-stop systems or tight compartments, the safest place for the red clamp is the marked positive post near the fuse box. Many owner manuals show that exact spot. The black lead still goes on the donor negative post first, then a ground on the disabled car.
If you want a second reference, this Consumer Reports step list matches the sequence above and adds photos that match most late-model layouts.
Special setups: remote posts, side-post batteries, and tight bays
Remote posts exist for a reason. Carmakers place them to keep you away from tight battery wells, sensors, and delicate modules. If you see a red cap with a plus and a nearby ground stud, those are your connection points. If the battery uses threaded side studs, wide clamps can slip. Use clamps made for side posts or the remote posts. If an engine bay is crowded, take an extra moment to route cables around belts and fans so nothing touches moving parts when the engine starts.
Some models hide the 12-volt battery in the trunk or under a seat. You will still find a red positive point under the hood. Use that for the red clamp, and a labeled ground or clean metal for the black clamp. The signals never change: red to “+”, black to “−” and to ground on the dead car.
Safety checks that save parts and fingers
Before you clip anything, scan both batteries. Skip the jump if any case looks swollen, cracked, or leaking. Wear eye protection and keep faces and hands out of the line of fire. Remove rings and metal bracelets. Keep sparks away from the battery and fuel lines. Ventilate the area so gas does not build up. If posts are caked with white crust, brush them enough to see the marks, then connect.
Electronics do not like reverse polarity. Crossing clamps or dropping a loose clamp on metal can short the system. That can take out fusible links, alternators, and engine modules in a blink. Slow down, match the symbols, and clamp on squarely. Keep clamps from touching each other at any time.
Hybrids, mild hybrids, and electric vehicles
These vehicles still carry a 12-volt system for computers, locks, and lights. That small battery is the one you jump, not the high-voltage pack. Never touch orange-sheathed cables or service plugs. Many hybrids place a dedicated positive post under the hood for this job. Use that post for the red clamp and a metal ground for the black clamp. If the layout looks unusual, check the owner manual for the pictured jump points before you proceed.
Troubleshooting when the engine will not crank
Lights on but only clicks? Give the donor car a few extra minutes at a fast idle. Headlights dim or no dash at all? The dead battery may be too far gone, or a clamp is not biting clean metal. Wiggle each clamp to confirm a solid grip. If the starter turns slowly and stops, pause to protect the starter and cables from heat. Try another ground point on the dead car if you see any tiny sparks at the last clamp.
Once the car starts, keep the engine running. Drive for at least fifteen minutes to bring charge back. If the next start later in the day feels weak, plan on testing the battery and charging system soon. That weak start hints at a battery near the end of its life or a charging fault.
Second table: cable order and removal cheat sheet
| Step | Action | Clamp |
|---|---|---|
| 1 | Connect to dead battery positive (+) | Red clamp |
| 2 | Connect to donor battery positive (+) | Red clamp |
| 3 | Connect to donor battery negative (−) | Black clamp |
| 4 | Connect to dead car ground point | Black clamp |
| 5 | Start donor, then start dead car | — |
| 6 | Remove from dead car ground | Black clamp |
| 7 | Remove from donor negative (−) | Black clamp |
| 8 | Remove from dead positive (+) | Red clamp |
| 9 | Remove from donor positive (+) | Red clamp |
If you use a portable jump pack
Many drivers carry a compact jump starter. The red lead still goes to positive and the black lead still goes to ground on the car you are starting. Power the pack only after the clamps are set, then switch it off before removing the clamps. Keep the pack charged based on the maker’s schedule and stow it where cabin heat will not bake it.
Care tips for cables and batteries
Quality cables make the job smoother. Thick copper conductors, springy clamps with sharp teeth, and clean jaws deliver current without drama. Store cables coiled, dry, and away from acid. If a clamp gets oily, wipe it off so it can bite. Keep a compact jump pack charged as a backup, and keep it out of extreme heat inside the cabin.
Batteries last longer when they stay clean and strapped down tight. A loose battery can rub through insulation or short a post against metal. Keep vent holes open. If you see white or green crust growing on posts, neutralize it with a dedicated cleaner and a rinse of water, then dry the area before the next drive.
Common mistakes to avoid
- Guessing by side instead of matching the “+” and “−” marks.
- Letting the last clamp spark near the battery instead of using a ground point.
- Clamping onto painted or oily metal that blocks current flow.
- Allowing cable jaws to touch a spinning pulley or fan.
- Revving the donor wildly, which adds noise but little extra charge.
- Pulling clamps off while an engine is revving.
- Skipping eye protection during close-up work around batteries.
When to call for help instead
If the battery case is swollen, posts are melted, or the engine bay smells like rotten eggs, leave the hood open and step back. Those signs point to internal failure. A tow or roadside visit beats a blown battery in your face. If jumper cables are new to you, that same roadside service can handle the jump and test the battery on the spot. AAA, local breakdown services, and many dealers offer that service.
Quick recap
Red to positive on both cars. Black to donor negative, then to a clean ground on the dead car. Start helper, then start the car with the flat battery. Remove in reverse order. Match the symbols every time and you will be back on the road without drama.
Posts unlabeled or hard to reach? Look for a red cap or a molded plus on the cable end. If uncertain, open the manual for your model. Symbols always beat position, and a clean ground makes starts smoother.