I am sure I read, or was told, that completely removing a battery from a car is bad because it resets things in the car's computer or it dumps some sort of acquired tuning data, or something along those approximate lines. I cannot recall or find the information again though.

My car (Jaguar S-type Petrol 3 litre, 2000) has been sat unused for about 3 weeks, and today I discovered that it will be another 3 weeks before it can go in for some much needed work. I don't want to drive it with work needed (some of it mildly safety related) until the short journey to the mechanics garage, so I am thinking a few days before I will take the battery out and charge it overnight (the battery in my car does not respond well to being left for long periods without being driven)

So I am wondering if there will be any issues with the battery not being in the car.

2 Answers 2


Should be fine. It will reset the ECU after a couple minutes (when the capacitors loose their charge). The shop will likely disconnect the battery while working on the car. Leaving the battery sit for a couple months should be fine as long as it was good to begin with. A weak battery may not last that long.


As the other user stated, the only thing it'll affect is the ECU, stuff like Idle speed, or different settings will be reconfigured, my only word of caution is when you put the battery back in and turn the car on, let it idle for a while so it can reconfigure everything such as idle speed so it doesn't run as rough.

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