If there's no negative terminal on your car battery (meaning it's missing or broken), you can't start the car conventionally because a complete circuit is needed; however, you can often jump-start it by connecting the negative jumper cable to any unpainted, solid metal part of the engine block or chassis, away from the battery itself, as the entire car body acts as the ground. Always connect the positive first, then ground the negative to the car's frame, never the battery itself, to avoid sparks near potentially flammable battery gases.
A: No, you cannot successfully jump-start a car using only the positive terminal. A complete circuit is required, which means you need both the positive and negative (ground) connections.
Always remember if you work with a battery that doesn't have any markings, the larger terminal is always the positive.
To check if your alternator or battery is bad, use a multimeter: a good battery reads ~12.6V (car off), while a running car with a good alternator reads ~14.2-14.7V; if it reads low or doesn't rise, the alternator is likely bad. Alternatively, try a jump-start: if the car runs briefly then dies, it's the alternator; if it starts and stays running, the battery might be weak but the alternator is okay.
Obvious Signs Your Car Battery Is Dying
The average cost to replace an alternator is typically $400 to $900, including parts and labor, but can range from $350 for easier jobs to over $1,500 for luxury vehicles or difficult-to-access alternators, with parts often costing $100-$900 and labor $200-$700 depending on your car's make, model, and alternator location.
Idling can charge a car battery, but it's slow and not nearly as effective as driving. The alternator produces more power at higher RPM, so you only get a partial and gradual recharge at idle.
Disconnect Battery Cables (Negative First!)
However, DO NOT disconnect the positive terminal before the negative one. Doing so can cause an electrical short.
Signs of a Dead Battery
When connecting a car battery or jumper cables, always connect the red (positive) cable first, then the black (negative) cable to a ground point away from the battery to prevent dangerous sparks from flammable battery gases. When disconnecting, do the reverse: black (negative) first, then red (positive).
You might need to recharge a battery after leaving the lights on and jump-starting it. It's a common occurrence, especially on vehicles that don't have protective systems that go to 'sleep' after a set time of inactivity. But a jump-start doesn't recharge the battery, so you'll need to run the engine to charge it up.
10 Wrong Ways to Jump Start a Dead Battery
Yes, you can often charge a dead car battery using a proper battery charger or by jump-starting it, but success depends on the battery's age and condition; if it's old, damaged, or suffers from sulfation, it might not hold a charge and need replacement, but a mild drain from lights left on can often be revived. A battery charger is ideal for a slow, safe charge, while jump-starting provides immediate power to get the engine running, allowing the alternator to recharge it.
Symptoms of a Bad Battery
Driving your vehicle is one way to recharge your car battery. The automotive experts at CAA Auto Advice say that driving your car for 20-30 minutes will help. Short distance trips may not be enough to get a full charge so be sure to check your driving time.
A car battery can drain when the car is off due to parasitic draws (interior lights, radio, faulty relays, aftermarket accessories like dash cams), a failing alternator preventing recharge, loose/corroded connections, or simply an old battery reaching the end of its life, with normal drains from the clock and alarm systems becoming problematic when combined with other issues.
When disconnecting the cables from the old battery, disconnect the negative first, then the positive. Connect the new battery in the reverse order, positive then negative.”
Can a dead car battery recharge itself? If your battery has run down completely, your car will fail to turn over, meaning it won't start. If you can't start your car, the alternator can't work, and it won't put any additional energy back into the battery, so it's impossible for a dead battery to charge itself.
Most alternators will last between 80,000 and 150,000 miles — or about seven years. However, your driving habits and the area where you live could wear it out prematurely.
While replacing an alternator yourself is possible, it is a complicated job requiring specialist tools. You might save money on labour costs, but the risks don't outweigh the benefits.
Symptoms of a bad alternator include a dashboard battery warning light, dim or flickering headlights, slow or malfunctioning electrical accessories (windows, radio), weird noises (growling/whining), a burning smell, and a frequently dead battery or difficulty starting the car, as the alternator isn't charging the battery or powering the vehicle's electrical system.
Most car insurance won't cover the cost of an alternator replacement, with a few exceptions. For example, if you have a full-coverage policy, an insurer will likely cover your alternator in a covered loss — though this excludes age and wear and tear losses.