I have a 2000 lexus es 300, last winter I put a new battery in it because it had been going dead. During the summer and fall it was fine but now this winter it’s dying again. I don’t drive it too often (once every week or two) but every time I go to drive it it’s dead again. It doesn’t seem to just be a cold thing (it will start within hours and typically days of last being jumped). It has also been known to die from idle, the most recent time I was waiting for my girlfriend at the airport and I was idling in the queue, I eventually got out to see if I could see her waiting somewhere else, so I turned the car off. When I got back in my car it was dead. Is energy leaking somewhere?
Has anyone bothered to check the alternator output?
They didn’t mention anything when I got the battery. Probably the issue?
“They didn’t mention anything when I got the battery”
Did “they” check the condition of the alternator?
A battery that dies w/in one year can only be attributed to one of the following factors:
A defective battery
A failing alternator
A short-trip driving pattern that does not allow the battery to be fully recharged
A parasitic current draw when the vehicle is shut off
In winter you are likely running your fan and have the headlights on along with driving at low speeds and idling a lot. Under these conditions an alternator might not be able to keep up with the load on the battery and the battery will discharge.
You may have an alternator that is marginal, that is that possibly a diode has opened up so it cannot supply the same current as a new alternator or the voltage regulator is not allowing enough field current to flow or maybe even the field current connection is corroded enough to restrict the alternator output.
Before you shut down, turn off the heater fan and the headlights and let the engine run for a minute or two. You might step up the engine speed to around 1500-2000 rpms while doing this.
+1 for @keith.