ENGINE or BATTERY?

I was wondering if any of u guys/girls would know wether all the electric devices in a car runs off the engine of battery? my friend said that everythin runs of the engine (i.e. air-con, sound system, lights etc) and that the battery is just used to start the engine, if this is tru then how come my lights/radio and aircon work while i'm on ACC (Accesories). Could anyone please confirm wether this is true or not? or give me a list on what runs off the engine and what runs of the battery cus if i keep using my speakers/air-con etc all the time, i'm afraid that i'll drain the battery, all help appreciated!!!

lol interesting theory. Well anyways, all the electrical stuff is powered by the battery. Howevery, you may think that soon you will need to replace your battery because all that stuff will drain it quickly. But actually the alternator-powered by the engines rotation-is connected to the batter and that recharges the batter everytime you are out cruising around. So have no fear, all electronics are run off the battery, and the battery is run off the engine.

lol interesting theory. Well anyways, all the electrical stuff is powered by the battery. Howevery, you may think that soon you will need to replace your battery because all that stuff will drain it quickly. But actually the alternator-powered by the engines rotation-is connected to the batter and that recharges the batter everytime you are out cruising around. So have no fear, all electronics are run off the battery, and the battery is run off the engine.


Man that reply was quick, thanks for the reply but i was wondering that if the battery runs off the engine and keeps getting recharged by the engine why do we need to replace batteries? Plus u say that all the electrical components runs off the battery, but my friend turned on his bike and while it was on, he took the battery out and said the lights still worked. Do you kno why? are bikes different to cars? just wondering if you or anyone else know's the answers to these questions :)

batteries need to be replaced over long periods of time, for instance ten years. The reason they need to be replaced is because the acids and metal plats inside them, wear away over time and eventually just cannot hold a charge anymore. Its the same as for instance a rechargable double A battery, after awhile it just cant hold a charge. Bikes i am not certain but i believe they run on a generator basis, the battery is not charged like on a car it is just there to start it and the engine runs a generator to keep all the lights etc working. That is why when you see a bycicle coming head on at night, the headlight will get bright/dim randomly.

Man you know ur stuff timberdoodle, thanks for the info!! just found a site which talks about alternators and ur 100% right, i'll trust ur judgement on bikes aswell, again thanks heaps!!!