Quick Answer: Yes, most completely dead batteries can be jump started, but you need to let the donor car run for 5–10 minutes first to push some charge into the dead battery before attempting to crank. If the battery is shorted internally, physically damaged, or fully sulfated from sitting dead for months, it may not accept a charge no matter what. A battery that won’t take a jump needs replacement.
What To Do
- Park the donor car close enough for cables to reach, but don’t let the vehicles touch. Nose to nose usually works. Turn off the donor car before connecting cables.
- Connect jumper cables in this exact order:
- Red cable to the dead battery’s positive (+) terminal
- Red cable’s other end to the donor battery’s positive (+) terminal
- Black cable to the donor battery’s negative (-) terminal
- Black cable’s other end to an unpainted metal surface on the dead car’s engine block (not the dead battery’s negative terminal, this reduces spark risk near the battery)
- Start the donor car and let it run for 5–10 minutes before attempting to start the dead car. This is the step most people skip. A completely discharged battery needs time to accept charge before it can crank an engine. Give it time.
- Try to start the dead car. If it cranks slowly and struggles, wait another 5 minutes and try again. If there’s nothing, no click, no crank, the battery may be too far gone or have an internal fault.
- Once started, drive immediately for at least 20–30 minutes to let the alternator recharge the battery. Short trips right after a jump start often result in coming back to another dead battery.
- Disconnect cables in reverse order: Black from engine block, black from donor negative, red from donor positive, red from your positive. This order prevents sparks near the battery.
- Get the battery tested within 48 hours. A battery that went completely dead may have suffered cell damage. Free testing at any auto parts store. If it won’t hold a charge, replace it.
What It Might Cost
| Situation | Cost |
|---|---|
| Jumper cables (owning them) | $20–$40 one-time |
| Jump start via roadside assistance | Free with membership |
| Jump start out of pocket | $50–$80 service call |
| Battery replacement if needed | $100–$250 |
| Portable jump starter (own one) | $50–$150 one-time |
Portable jump starters are worth owning. A compact lithium jump starter pack fits in your glove box and can jump your car without needing another vehicle. Brands like NOCO Boost or Clore/JNC make reliable units. Removes your dependency on finding a willing stranger.
Stay Safe
- Never jump start a battery that is cracked, leaking fluid, or visibly swollen. Battery acid and hydrogen gas from a damaged battery can cause serious injury.
- Keep your face away from the battery when connecting and disconnecting. Even a small spark near battery gases is a hazard.
- If the dead car’s electrical system starts behaving strangely after a jump (warning lights flickering, modules resetting), disconnect and have a mechanic check for voltage spike damage before driving.
- In cold weather below 10°F, batteries lose significant cranking power. Let the donor run longer, 10–15 minutes, before attempting the start.
Common Questions
Q: How long should I let the donor car run before trying to start my dead car? A: Let the donor car run for at least 5 to 10 minutes before attempting to crank the dead car. In cold weather below 10 degrees Fahrenheit, extend that to 10 to 15 minutes since batteries lose significant power in the cold.
Q: Why won’t my car start even after jumping it for a while? A: If there is no click and no crank at all, the battery may have an internal short, physical damage, or severe sulfation from sitting dead too long, and it will not accept a charge no matter how long you wait. At that point the battery needs to be replaced, which you can confirm with a free test at any auto parts store.
Q: Do I need to drive somewhere after a jump start, or can I just park it again? A: You should drive for at least 20 to 30 minutes immediately after a jump start so the alternator can recharge the battery. Parking it again right away or taking only a short trip often means you will come back to another dead battery.
Need roadside help? Visit Tow With The Flow for real answers when your car breaks down.