Why can't see the battery solar street lamps?

Why can't see the battery solar street lamps? Solar street light is composed of the following several parts, including solar panels, light source, light pole, lamp arm, controller, battery. Among them, the solar street lamps, we can see there are solar

why can't see the battery solar street lamps? Solar street light is composed of the following several parts, including solar panels, light source, light pole, lamp arm, controller, battery. Among them, the solar street lamps, we can see there are solar panels, light pole, light source, lamp arm and controller and the battery is not we can see, if open the electrical appliances, LED lamps, we can also see control, the battery is still can't see, so the controller where go to? Why we can't see the battery? Battery 1 there are two main types of solar street lamps, colloid battery colloidal battery is buried in the ground commonly, so we can't see. Colloid storage battery is through a sealed battery box buried, have the effect of waterproof, warm. There are also some colloidal battery is put above the light pole, an iron battery box fixed on the light pole, colloid storage battery in it. 2 lithium batteries, lithium battery solar street lamp solar street lamp lithium battery is usually on the solar bracket at the bottom of the, because the volume is not large, many people don't know what is it, there is also a part of the lithium battery is installed in the lamps and lanterns, so is not easy to see.