can trickle charge car battery with another car

[DeVera]

Yes, you can absolutely charge a car battery with another car, a process commonly known as a jump-start. The key is to do it correctly to avoid damaging either vehicle's electrical system. You'll need a set of jumper cables and a functional car with a charged battery. The core principle is creating a temporary series circuit to transfer power from the good battery to the dead one.

Here’s the safe, step-by-step method:

1. Position the Cars: Park the working car close to the one with the dead battery, but ensure they do not touch. Turn off both engines and engage the parking brakes.
2. Identify Terminals: Locate the positive (+) and negative (-) terminals on both batteries. They are usually marked clearly in red (positive) and black (negative).
3. Connect the Cables:
   • Red to Dead: Connect one end of the red (positive) cable to the positive terminal of the dead battery.
   • Red to Donor: Connect the other end of the red cable to the positive terminal of the good battery.
   • Black to Donor: Connect one end of the black (negative) cable to the negative terminal of the good battery.
   • Black to Ground: This is a critical safety step. Instead of connecting the final black clamp to the dead battery's negative terminal, attach it to an unpainted metal surface on the car's engine block or chassis. This provides a solid ground and helps prevent sparks near the battery, which can emit flammable hydrogen gas.
4. Start the Donor Car: Start the engine of the working car and let it run for a few minutes. This allows the donor car's alternator to begin feeding power into the dead battery.
5. Start the Dead Car: Attempt to start the car with the previously dead battery. If it starts, let both cars run connected for a few more minutes.
6. Disconnect in Reverse Order: Carefully disconnect the cables in the exact reverse order you connected them: black ground clamp, black donor clamp, red donor clamp, and finally, red dead battery clamp.

To ensure a successful jump-start, it's helpful to understand the fundamentals. The following table outlines key electrical specifications and considerations for a typical 12-volt automotive system.

Specification / Consideration	Typical Value / Detail	Note
Battery Voltage	12.6 Volts (fully charged)	A reading below 12.0V often indicates a battery needing a charge.
Alternator Output	13.5 - 14.5 Volts	The alternator's job is to charge the battery while the engine runs.
Jumper Cable Gauge	4 or 6 Gauge (AWG)	Thicker cables (lower gauge number) allow for better current flow.
Critical Safety Step	Connect negative cable to chassis ground	Prevents sparks near the battery, reducing explosion risk.
Charging Time	5-10 minutes before attempting start	Allows the dead battery to accept a minimal surface charge.

After a successful jump-start, you should drive the vehicle for at least 20-30 minutes to allow the alternator to fully recharge the battery. If the battery dies again soon after, it may be old, damaged, or there could be an issue with the vehicle's charging system, like a faulty alternator. In that case, a professional diagnostic check is recommended.

[McEsther]

Yep, it's totally doable. Just grab some jumper cables. Hook up the red clips to the positive terminals on both batteries. Then, connect one black clip to the good battery's negative terminal. For the last black clip, don't put it on the dead battery. Clip it to a clean, unpainted metal part of the engine. Start the good car, wait a minute, then try starting the dead one. It usually fires right up. Just be careful not to let the clamps touch.

[MacQuinn]

Think of it as a temporary power transfer. The goal is to use the healthy car's electrical system to provide just enough energy to crank the starter motor on the disabled vehicle. The most common error I see is incorrectly connecting the negative cable directly to the dead battery's negative post. Connecting it to a metal ground on the engine block is safer because it minimizes the risk of a spark igniting hydrogen gas that batteries can emit. This method is a reliable fix for a simple discharged battery, but it won't help if the battery itself has a internal fault or is completely dead from age.

[VincentLynn]

Alright, so my dad taught me this years ago and it's saved me more than once. You gotta get the cables right. Red on the positive of both batteries, easy. Black on the good battery's negative. The trick is the last black clamp—find a solid bolt or bracket on the engine of the car that won't start. That's your ground. Once everything's secure, fire up the running car, give it a second, and then turn the key on the other one. If it doesn't crank right away, wiggle the clamps to make sure they're biting in. A jump-start is a quick fix, not a permanent solution, so you'll want to drive it for a good while afterward.

[DeSara]

This is a standard roadside recovery technique. The process effectively uses the donor vehicle's alternator as a high-amperage booster to supply the necessary current. It's crucial to confirm that the battery is simply discharged and not physically damaged. If the battery case is cracked, swollen, or leaking fluid, do not attempt a jump-start, as it presents a significant safety hazard. Furthermore, many modern vehicles with complex electronics can be sensitive to voltage spikes. Using a modern portable jump starter pack, which often includes surge protection, can be a safer alternative to using another car, especially if you are unsure about the procedure.