Do Car Solar Battery Chargers Work?

Solar chargers can be used to charge a car battery—but how effectively?

car solar battery charger
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Unlike standard battery chargers, which have to be plugged into power outlets, solar chargers work anywhere with a clear view of the sky. But can a solar battery charger really deliver enough juice to charge a car battery?

Do Solar Car Battery Chargers Actually Work?

While solar battery chargers do work, they have some important limitations. They are not nearly as powerful as standard car battery chargers, so you shouldn't expect to charge your battery as quickly as you would with a regular charger.

Unlike standard chargers with multiple amperage settings, solar battery chargers typically put out a very small amount of current. For that reason they are more useful for maintaining a charge than reviving a dead battery. You can use a solar car battery charger as a trickle charger, but you'll be left cooling your heels if the battery is completely dead.

How Solar Battery Chargers Work

Solar battery chargers work by converting energy from the sun into electricity that can be stored in a battery. This is accomplished via a photovoltaic solar panel, which is the same basic technology used in residential and commercial settings to provide on-site power.

However, the solar panels used in solar battery chargers are nothing compared to the ones used in residential or commercial solar systems. While the technology is the same, the panels used in solar car battery chargers are typically only capable of putting out, at most, 1,500 mA. And while you can technically tie multiple chargers together, doing so is dangerous if you aren’t familiar with the technology.

Can Solar Battery Chargers Charge Car Batteries?

The amount of amperage a solar battery charger can produce depends on several factors, including the build quality and how much sunlight is available. On average, they put out between 500 and 1,500 mA. This is why solar chargers are more effective as trickle chargers.

One issue is that most solar chargers don’t include a voltage regulator to modify or shut off the flow of power. That means you cannot "set it and forget it," as you would with a float-monitoring trickle charger.

The best way to use a solar charger is to provide more amperage at the start and then ramp it down as the battery nears a full charge. High-quality chargers are capable of doing this automatically, and other chargers include manual controls that allow you to set a “course” rate to start and a “fine” rate to finish up.

As with any solar charger, sunlight is crucial. If all you can manage is 500 mA on a cloudy day in a northern latitude, then that's all you'll get. They may be handy in a pinch, but temperamental availability means you probably can't depend on them.