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Q: Changed battery twice in 2 weeks, I go to turn on and car is completely dead not even the lights work, what could it be? 2000 Acura TL

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I just got my car back friday after having the transmission fixed and noticed it making weird sounds like its idling weird and last week battery was completely dead not even lights worked and now again today I went to turn on the car and nothing! no lights the locks didn't even work and I didnt drive it all weekend. Why would it keep dying like that?

My car has 200000 miles.
My car has an automatic transmission.

A: Hi there - a repeating "dead battery&q...

Hi there - a repeating "dead battery" scenario has a couple of possibilities. One possibility is a bad alternator that is not charging properly. With the engine running, the system voltage should be close to 14 volts if the alternator is charging correctly. The second possibility is that something is draining the battery when the car is turned off. This problem can be diagnosed by connecting an ammeter to the positive (red) battery cable, observe the current drain (likely less than 1 amp), then, one at a time, remove each fuse, check to see if the current drain has dropped to near 0, then reinsert the fuse. This process should identify the faulty circuit in most cases. A professional mechanic, like YourMechanic, can perform this diagnostic procedure for you, and replace/repair the failing component.

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