You can charge a car battery without a dedicated charger using several improvised methods, especially in emergencies:

Using Another Car and Jumper Cables

• Connect the red positive (+) jumper cable to the positive terminal on both the dead battery and the good battery.
• Connect the black negative (-) jumper cable to the negative terminal on both batteries.
• Let the dead battery charge for 5-10 minutes while the other car is running.
• Then try starting the car with the dead battery.
• Remove the cables in reverse order once done

Using a Portable Jump Starter

• Connect the jump starter’s positive and negative clamps to the corresponding terminals on the car battery.
• Let it charge for a few minutes, then start the engine.
• Disconnect and recharge the jump starter after use

Using the Car’s Alternator by Jump Starting

• Jump start the car using jumper cables or a jump starter.
• Once the engine is running, the alternator will charge the battery.
• Keep the engine running for a while to allow charging.
• Note this is not an ideal charger and may not fully charge the battery efficiently

Using a Solar Panel

• Connect a solar panel designed for 12V batteries to the battery terminals.
• Place the panel in direct sunlight for slow, trickle charging.
• This method is slow but useful if no other power source is available

Using Another Battery as a Power Source (for small batteries)

• Connect a fully charged battery with matching voltage to the dead battery terminals using insulated wires.
• This can slowly transfer charge but requires careful monitoring to avoid damage

Important Safety Notes

• Always connect positive to positive and negative to negative terminals.
• Avoid fast charging without proper equipment to prevent battery damage or hazards.
• Improvised charging methods are temporary solutions until you can use a proper charger

These methods can help you get your car battery charged enough to start your vehicle or maintain charge until you can access a proper charger.