You do not need to remove the battery from the vehicle to assess it or to clean it. To simply access the battery, pop open the car hood and locate the battery. It’s typically on the front-left side of the engine block. Visually inspect the general condition of your car battery. If the battery is not cracked or leaking battery acid, you can go ahead and start cleaning. If your battery case has cracks, you should replace the entire battery. Visit a local auto-parts store and purchase a battery there. Lift up and to the sides the plastic covers on top of the battery. This will reveal the terminal/clamp interface. Examine the battery cables and clamps for excess wear or corrosion. Corrosion appears as a white, ashy deposit around one or both battery posts. If the cables and clamps are lightly corroded or have just a little buildup, follow the instructions below on how to clean them. If the damage is extensive, you may want to completely replace the cables and clamps to avoid future problems. Before cleaning the battery, you’ll need to disconnect the battery. To do this, loosen the nuts on the clamps using a wrench. Once loosened, remove the negative clamp, marked with a “-” first. Only after the negative clamp is removed, remove the positive clamp, marked with a “+”.  The clamps may prove difficult to remove, especially if there is a lot of corrosion. You may need to use pliers to remove them. If you do need to use pliers be careful not to touch the tool to the car frame (or anything else metal) and the battery while working. Doing so will short out the battery. Combine 2–3 tablespoons (30–44 mL) of baking soda with 1 tablespoon (15 mL) of distilled water in a small bowl. Stir the ingredients together with a spoon to make a thick paste. Keep stirring until all of the bits of baking soda are fully dissolved in the water. Baking soda is alkaline, which means that it’s capable of neutralizing corrosion from battery acid. Dip an old toothbrush or a lightly dampened rag into the baking soda paste. Rub the paste onto...

TL;DR in Indonesian:
Buka kap mobil dan nilai kondisi aki. Telaah tingkat korosi pada aki dan kabel. Lepaskan penjepit negatif dan positif pada kabel aki. Buat agen pembersih dari soda kue dan air. Oleskan pasta soda kue pada sambungan aki. Kikis endapan korosi dengan pisau mentega bekas. Bilas aki dengan air kalau sudah disikat bersih. Lap terminal sampai bersih dengan kain lap kering. Usapkan vaselin pada terminal bersih untuk mencegah korosi. Pasang kembali 2 penjepit ke aki.