Modern cars are made to be low maintenance which means you rarely have to go under the bonnet to see if everything is okay with the engine. Its fine to be able to relax, or at least it is until the day you turn the key in the ignition and nothing happens. One of the most common reasons for this is corrosion collecting around the battery terminals. The funny thing is the less you drive the car, the more likely this is to happen.
Car cleaning of this kind does not fall within the scope of normal home cleaning that is done by a professional agency. And calling a mechanic when this happens is a needless expense. Cleaning your battery terminals is something you can easily do yourself. Do it once a month as a preventive measure so that you don't get stuck unexpectedly.
Put on rubber gloves and a pair of protective goggles. Open the bonnet and loosen the nuts on the clamps holding the battery cables to the terminals. Make sure you always disconnect the negative (-) terminal first and then the positive (+) one. They will be clearly marked. If the cable does not come off easily you may have the shake and wiggle it free. If need be use a pair of pliers to move the clamps till they are loose.
Check the cables and clamps for excessive wear or corrosion damage. If the damage is great replace them. Place the cables securely away from the battery so they cannot come into accidental contact with it. Now pour some baking soda onto the battery terminals and scrub with a wet toothbrush until the terminals are clean and shiny. Now take each of the cable clamps and do the same thing with them.
Dry off the terminals and the clamps with a clean dry cloth. Refit the terminals to the battery but this time fit the positive one first and them the negative. Tighten the clamps to the terminal. Spread petroleum jelly over the exposed terminals and clamps to slow down any future development of corrosive deposits. Do not use grease as it is a bad conductor of electricity and can damage the battery.
The positive terminal should have a rubber or plastic boot to cover it. Make sure that this is replaced and if the boot is missing, buy one from an auto supply store.
Now you're ready to drive.