can you charge a car battery with a power supply

[DeLiam]

Yes, you can charge a car battery with a power supply, but it is not as simple as just connecting the wires. You must use a power supply that is specifically designed for the task, often called a bench power supply or a manual battery charger. A standard laptop-style power supply will not work and can be dangerous. The critical factor is that the power supply must provide a constant voltage, typically between 13.8V and 14.4V, and allow you to limit the maximum current, usually to around 10 amps or less for a standard car battery. This mimics the voltage output of a car's alternator.

Connecting a battery directly to an unregulated power supply can cause it to overheat, release toxic gases, and potentially explode due to excessive current. The process requires careful monitoring. You connect the positive clip to the battery's positive terminal and the negative clip to the negative terminal, ensuring a secure connection. You then set the voltage and current limits correctly before turning on the power supply. It's a slower charging method best suited for maintenance or recovering a deeply discharged battery, not for a quick jump-start. For most people, using a modern, automatic smart charger is a much safer and more convenient option.

Key Parameter	Recommended Setting	Why It Matters
Voltage Output	13.8V - 14.4V	Matches an alternator's output; higher can overcharge, lower won't charge fully.
Current Limit	2-10 Amps	Prevents damage from excessive heat; slower charging is safer for the battery.
Battery Type	Lead-Acid (Wet, AGM, Gel)	Using the wrong charging profile can damage AGM or Gel batteries.
Charging Time	4-24 hours	A 50Ah battery discharged to 50% at a 5A charge rate takes ~5 hours.
Safety Feature	Spark Proof, Reverse Polarity Protection	Essential to prevent accidents during connection.

[LaJames]

As a mechanic, I've used a bench power supply for this. It works, but you have to know what you're doing. Set it to constant voltage mode at about 14.2 volts and limit the current to 5 or 10 amps. You can't just walk away from it like a smart charger. You have to watch it and check the battery's temperature. It's a useful trick in the shop for testing or reviving a dead battery, but I'd tell any customer to just buy an automatic charger. It's safer and you don't risk ruining a good battery.

[VanAdaline]

I tried this once in my garage with an old PC power supply I modified. It was a bit of a project. You have to make sure it can handle the load and wire it correctly. It charged the battery, but very slowly, and I was nervous the whole time. Honestly, it's not worth the hassle unless you're really into electronics and understand the risks. A basic charger isn't that expensive and does all the thinking for you.

[DiJulian]

The main thing is safety. A car battery can produce explosive hydrogen gas when charging. A proper battery charger is built to manage this risk. A random power supply is not. You also risk damaging your vehicle's sensitive electronics if the voltage isn't perfectly stable. If you value your car and your safety, the right tool for the job is a dedicated car battery charger. It's a small investment for peace of mind.

[McBrielle]

Technically, yes, but it's all about control. You need a regulated DC power supply where you can precisely set the voltage and current. Think of it like a slow, manual trickle charge. It's not for giving you a quick start; it's for carefully bringing a battery back to life over many hours. You must monitor the amperage as it drops; when it holds a steady voltage and the current tapers off, it's likely full. This method is for enthusiasts who understand the principles, not for someone who just needs their car to run tomorrow.