Can A Portable Power Station Charge A Car Battery?

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Trying to get your car battery some juice while on a camping trip, or is your car just stranded with a dead battery? If you happen to have a portable power station (PPS) at hand, you could possibly charge your battery enough to start the engine. 

Now, if by "battery" you meant an EV battery, now that's a different story. Most portable power stations don't have the voltage or capacity to handle a fully electric vehicle's battery. That said, if your PPS has a 120V AC outlet and can also deliver at least 1,200W continuously, you could use a standard level 1 EV wall outlet charger to slowly (and inefficiently) get some power into your EV. That could be helpful if you just need a tiny bit of range to get to another location in an emergency.

What we'll focus on here is charging the 12V battery found in gas-powered or hybrid vehicles, and some modern EVs, too. What kind of power station can do it? What specs matter? And how long will it take to get enough charge to turn the key?

Assuming you've got a 12V car battery ready that's worth recharging, the first thing you'll need is a power station with a DC output — typically a cigarette lighter port that delivers more than 12.6V. That's because a healthy lead-acid 12V car battery at rest usually sits around 12.4V to 12.6V, and you need a higher voltage to push current into it.

If your power station's DC output delivers less than that, it likely won't charge the battery effectively, especially if the battery is deeply discharged. While your power station's manual may label the output as "12V," many higher-end units actually regulate it at 13.2V to 13.6V, which is better suited for basic battery charging.

For example, the 12V 30A DC output on the Bluetti AC200MAX is regulated at 13.5V, which means it can supply power until your battery reaches that same voltage. Once the battery approaches 13.5V, the charging current will slow down or stop because the voltage difference between the source and the battery gets too small to keep pushing energy in. if you're not sure what voltage your battery or power station is currently putting out, you can check using a digital multimeter.

Next, you need to look at your portable power station's capacity in watt-hours. Car batteries would need between 400 to 800Wh (depending on the voltage and amp-hour combination) so you should have a power station with around 1,000Wh — accounting for inefficiencies and energy loss.

Once you've confirmed your power station meets the recommended specs, you'll need to get a DC-DC battery charger (like this 50A Renogy), a DC power cable to plug the PPS to the battery charger, and of course battery cables to connect your car battery to the battery charger. These requirements might change depending on your battery, so make sure to look at the fine print. Now, you just leave it to charge, and it should take about six hours to fully charge a 12V 50A battery using a 12V 10A DC outlet on your PPS.

On the other hand, you could just use the 120V AC outlet on most power stations. It works like a car battery wall-charger, converting the power station's AC to DC for battery charging. The reason we don't recommend this is that it's not as efficient, and you can expect to lose up to 20% of power due to converting DC to AC and then to DC again.