Can you take the battery out of a car and leave it overnight

[supercommuter]

My friends Mini Countryman Cooper SD (2013/63) wont start after being left for 4/5 hours, but once jump started it runs with no issues. So assuming there is a drain somewhere or the battery is faulty.

Wanted to get the car running and charge the battery, switch it off and then disconnect the battery to see if it is holding charge without being connected but cautious about removing a battery for any period of time as there are 'lots of electronics' on newer cars.

Any immediate concerns with doing this?

He hopes it is just the battery and not a drain somewhere!

[lufbramatt]

No it will be fine.

Some cars can be funny about disconnecting the battery while the car is still "awake", won't do sat navs etc any good if they are turned off while reading the disc, so might have to open the bonnet then leave the car for 20 mins for everything to turn off before disconnecting the battery.

[Johnnytheboy]

Weirdly you might find it confuses the electric windows, if it's anything like a couple of cars I've had.

[Mike1990]

Johnnytheboy said:

Weirdly you might find it confuses the electric windows, if it's anything like a couple of cars I've had.

Yeah this happened on my Corsa a while back after I changed the Battery, the one touch electric windows didn’t work :S it needed a few days for it the work again. Strangely though i didn’t loose my radio stations or have to put my code in.

Suppose every car is different.

[996TT02]

Indeed, while certainly possible, it would be best to look into the specifics for any particular vehicle. With one of mine, self-dropping windows for easy door opening and closing, and the car's alarm, both separately need to be taken into consideration when disconnecting. And, not forgetting the battery location, which is opened electrically (!!). Stuff like electric windows and fuel calibration also affected but these (in mine) eventually sort themselves out with no action needed. So, just be well informed.

[Ninja59]

Windows are the least of your issues if it has an IBS (like all current BMW's and F series cars).

I don't know if BMW fitted an IBS to the minis of this generation, but I highly suspect it will have an IBS.

If it does then it will use (or should be using!) an AGM battery and it would need programming to the car to make sure the charge is correct. I do wonder if an incorrect battery (if it has been replaced) or a new battery that has not being programmed is part of the problem.

[MatthewH5]

Electric windows can usually be recalibrated by rolling each window fully down/up while holding the button for an extra 3 seconds.

[supercommuter]

Ninja59 said:

Windows are the least of your issues if it has an IBS (like all current BMW's and F series cars).

I don't know if BMW fitted an IBS to the minis of this generation, but I highly suspect it will have an IBS.

If it does then it will use (or should be using!) an AGM battery and it would need programming to the car to make sure the charge is correct. I do wonder if an incorrect battery (if it has been replaced) or a new battery that has not being programmed is part of the problem.

It still has the original battery. I may call mini and ask them, but i was told this was not the case :| so not sure now!

[cbmotorsport]

A 2013 car with the original battery? I'd wager that this is the problem. Its just not holding charge. With Winter coming, I'd change it anyway.. It will let you down at some point anyway.

[hornmeister]

Might be the battery or a drain somewhere. Really need to sort out which. Maybe the battery is no longer holding a charge? Woul certainly change it as above.

Hhow about one of those solar powered trickle charger things. They can be bought from £30 or so.

Edited by hornmeister on Monday 24th September 11:41

[t400ble]

Mike1990 said:

Yeah this happened on my Corsa a while back after I changed the Battery, the one touch electric windows didn’t work :S it needed a few days for it the work again. Strangely though i didn’t loose my radio stations or have to put my code in.

Suppose every car is different.

You just program the soft close function back in on the switch, takes seconds to do.

[Ardennes92]

Some vehicles throw a wobbly if you don't follow set order to disconnect the battery, usually earth terminal (negative) first

[98elise]

Johnnytheboy said:

Weirdly you might find it confuses the electric windows, if it's anything like a couple of cars I've had.

Yup. When we changed the battery on our focus convertible the windows took a few days to get over the "shock"

[cobra kid]

cbmotorsport said:

A 2013 car with the original battery? I'd wager that this is the problem. Its just not holding charge. With Winter coming, I'd change it anyway.. It will let you down at some point anyway.

Mine's a 2007 with the original! Just showing the signs now though.

[996TT02]

In the 996, all it takes is fully operating the windows to the limits so that one-shot opening and closing is re-learned. This is memorised when the ignition is turned off (I guess) as they only work normally on next start up.

[chris4652009]

Ardennes92 said:

Some vehicles throw a wobbly if you don't follow set order to disconnect the battery, usually earth terminal (negative) first

this^^^^

[cbmotorsport]

cobra kid said:

cbmotorsport said:

A 2013 car with the original battery? I'd wager that this is the problem. Its just not holding charge. With Winter coming, I'd change it anyway.. It will let you down at some point anyway.

Mine's a 2007 with the original! Just showing the signs now though.

Sure, not saying that they have a lifespan, but as a modern car it's more likely to be a borked battery than a drain imho. :-)

[paintman]

supercommuter said:

My friends Mini Countryman Cooper SD (2013/63) wont start after being left for 4/5 hours, but once jump started it runs with no issues. So assuming there is a drain somewhere or the battery is faulty.

Wanted to get the car running and charge the battery, switch it off and then disconnect the battery to see if it is holding charge without being connected but cautious about removing a battery for any period of time as there are 'lots of electronics' on newer cars.

Any immediate concerns with doing this?

He hopes it is just the battery and not a drain somewhere!

This will not fully recharge the battery. it needs to be fully recharged using a battery charger.
Asking the alternator to keep charging a flat battery is also likely to damage the alternator. Not just my opinion: https://www.optimabatteries.com/en-us/experience/2...

[E-bmw]

paintman said:

This will not fully recharge the battery. it needs to be fully recharged using a battery charger.

^^^^This.

[supercommuter]

We charged it using a trickle charger, took it down to halfords, they did a battery test and then recommended a replacement, which they did. They have left the car 24 hours and will try to start it later.