3. Choose the right power output
Depending on the type of device(s), you may want to consider power output - or how fast a device can be charged. For this, you need to know the amps and volts of the charger. In general, the higher the amps, the faster the charge (some phones, like the iPhone, will only draw 1 amp, regardless of how many amps the charger has, but will not be harmed from a higher amp device). For a tablet, with a larger battery, you may want to consider a charger that has a 2 amp output to avoid extended charging times.
Some units may also have multiple outputs so that you can charge more than one device at a time. Most devices have shared circuitry where multiple devices will compete for the power. If you have a 2 amp circuit and are charging two cell phones pulling 1 amp each, this is not a problem. But if you don’t have enough power output, charging multiple devices (like two tablets) at the same time can significantly slow down the charging time for both units. In contrast, some devices have split circuitry, where each port has its own circuitry and can maximize the charging rate for each port.
4. Account for Safety and Longevity
There are two considerations that can help you understand how safe your device is:
With solar chargers or any battery pack, quality goes beyond the device itself. A low-quality product has the potential to harm the devices you are charging. Look for terms like “overcharge” protection that will protect the battery of your phone. “Overcurrent” protection is another important feature that limits the amount of power going in and out of the device to protect the circuitry on both devices. A good quality device will mention its safety features.
There are certifications that can help you assess the safety and performance of a device. CE and FCC certifications should be the bare minimum for any electronics. For solar lights, there is also the Lighting Global standard which is a World Bank initiative that supports sustainable growth of the international off-grid solar market by verifying the performance of solar lighting products.