Most portable solar chargers have smaller panels of around two watts or less, so the panel serves as a slow, emergency-charging system and the battery does the lion’s share of the work. If you know you’ll be away from an electric outlet for a while and need to rely more heavily on the solar aspect of the unit, you’ll. .
Consider how many devices you’ll be toting along with you that will need a recharge, and how often you’ll be away from an outlet for a. .
Many chargers have convenient features like wireless charging, flashlights, and carry handles. If you plan on hiking, going kayaking or rafting, mountain biking, or other active adventures consider a charger that’s also waterproof or shockproof.
[pdf] Notice that at 100% capacity, 12V lithium batteries can have 2 different voltages; depending if the battery is still charging (14.4V) or if it is resting or not-charging (13.6V). What is interesting to see is that a 12V lithium battery has an actual 12V voltage at only 9% capacity. Here is the 12V lithium battery. .
As you can see from this 24V lithium battery state of charge chart, the relative relationship between voltage and battery capacity is the same. .
You can see that 48V lithium battery voltage ranges quite a lot; from 57.6V at 100% charge to 40.9V charge. The 48V voltage is measured. .
3.2V lithium batteries are those regular batteries you put in older TV remote controls. Here are the voltage discharges: As you can see, 3.2V LiFePO4 battery can output anywhere.
[pdf] 
