why does my battery keep getting drained =(

[Gary DuBois]

when i have my 02 ranger 4.0 v6 sitting for a few weeks my battery drains to 0%.

I have checked fuses and the fuses are good - Is there any fuses i need to check under the hood ?

Could it have something to do with my current alternator ?

I make sure everything is off inside the cab when i have my ranger sitting for a few weeks

Thank You,
Gary DuBois

 

[franklin2]

Get a testlight. Take the negative battery cable off and lay it on a rag. Clip the testlight onto the negative battery terminal and then probe with the testlight the cable on the rag. If the testlight glows bright, you do have a drain. You can then pull fuses to see if you can get the light to go out. Make sure you have the doors closed, the domelight will cause the testlight to light. If you cannot find any fuses to make the light go out, make sure to disconnect any other aftermarket amplifiers and such, and see if that makes the light go out. If you still cannot get the light to go out, then disconnect all the wires on the alternator. If the light goes out with the alternator disconnected, then yes you have a bad diode in the alternator.

 

[gaz]

@Gary DuBois
If you aren't driving a vehicle for weeks at a time, some vehicles or batteries need to be on a trickle charger. Could age of use on the battery but could be a fault in the vehicles electrical system.

I would have check the battery if it is good, then I would use a trickle charger when not in use for weeks.

 

[Lefty]

A test light really helps. People have found parasitic draws from a number of sources: relays, faulty radio clock, loose connectors on the cruise control, etc.

 

[Curious Hound]

Do you leave anything plugged into the cigarette lighter or any other power ports? Phone chargers and other devices often draw current when plugged in even if they aren't being used.

Using a test light as outlined above is a good start. I prefer to use a multimeter so I can measure exactly how much current is flowing. Disconnect the negative battery terminal. Then connect the meter between the negative battery terminal and the negative battery cable. Make sure the meter leads are plugged into the proper ports on the meter for measuring amps. And set the selector switch on amps. Have the meter sitting where you can see it with all the vehicle doors and hood closed. Then close everything and leave the truck for about an hour. When you come back to look at the meter, don't open the hood or doors. You are hoping to see a reading down around 0.070amps or less. That is 70 Milliamps. Closer to 30milliamps is preferred.

The reason for leaving the truck for a while and not disturbing it is that there are timers in newer vehicles that turn things off after a while. Such as the dome light. It will remain on for a while and then the timer turns it off. If you open a door, it turns back on and then you see higher current flow. The dome light is just one example. I believe most things are shut down within a few minutes. But I don't remember the exact times.