What causes short circuits?

Question

My battery twice now has been discharged for no apparent reason, however according to my mechanic is due to short circuits.What is this and what causes it? Thanks

Answer 1

Usually power runs from the positive battery terminal, through a "load" (like the headlights or dome light, for example) then to chassis ground, which is connected back to the battery's negative terminal.

A short circuit occurs when the power wire is connected directly to chassis ground without passing through the load first.

Short circuits usually result in blown fuses or melted wire harnesses, not drained batteries.  A diagnosis of "short circuit" is actually pretty useless unless the mechanic knows which circuit is shorted.

It sounds much more likely that you have a parasitic drain.  This could be something as simple as a light in a glove box that's not turning off.  There's a procedure for tracking down and finding parasitic drains.  If your mechanic doesn't know how to do this, you might want to find a different mechanic.

Answer 2

electrical wires are insulated to insure the current reached its target..when the insullation is broken and the bare wires is now touching metal the current is then redirected (to ground) ergo its taken a short cut or simply put a short...however since this can cause a things to melt there are protection devices inline of the electrical crkt (the fuse) well with that said lets figure out how to isolate this problem...first the battery has been discharged because of a draw..to isolate the draw we need a test lite ...first confirm the lite works and do it periodacly to insure proper diagnosis. disconnect the pos term from the battery and clamp the test lite to the battery.

now touch the pointed end to the battery cable if the lite glows energy is being circulated and making the lite work this confirms a draw exist, now secure the battery cable away from touching any thing metal. have someone remove the fuses one at a time and reinstall them till the lite goes out. when it does you isolated the effected circuit. now before doing all this a faulty battery can cause same symptom be sure to have it tested first..prefferably by someone else also common causes of this symptom are underhood,glove box and or trunk lites that dont turn off also if the radio display stays on all the time after a day or two it will drainthe battery....goodluck hunting

  

Answer 3

that,s when a bare hot wire touches bare metal. if your battery discharges, then it,s probably the voltage regulator.

Answer 4

corrosion & moisture are the usual reasons for a short circuit. They allow current to pass through unchecked. Water & corrosion act as electrical pathways & are conductive.  

Answer 5

what he means is that somewhere in the wiring system there is a live wire transmitting electricity directly to the ground system.  This causes the electricity of the battery to be wasted.  it is the same as leaving on a light or a fan on the vehicle, so, it is imperative to find the wire 'short', most often there are on some 'add on' system, like a new stereo, or running lights, or sometimes it is just a worn area of insulation on the live wire-use an ohm meter to find the drain, it takes time, but it is not difficult-you may want a pro to do this, as it can be frustrating...good luck, and be safe.