Accidently unplugged POSITIVE first (not negative)

derek.megyesi · 04-25-2022, 04:01 PM

Hi all,

I am terribly nervous. I had to do some maintenance on my 430XI (F36) yesterday and in my haste to disconnect the car battery, I removed the POSITIVE (RED +) (not the negative, it stayed connected).

Everything got done, but when I put back on the positive, it sparked a bit. I tightened it up, and everything seem fine (no weird sounds or glitches).

I am terribly worried (and

at myself) now. Did I cause hidden damage, by undoing the POSITIVE first (not the negative)?

freespirit · 04-25-2022, 07:29 PM

Quote:

Originally Posted by derek.megyesi

Hi all,

I am terribly nervous. I had to do some maintenance on my 430XI (F36) yesterday and in my haste to disconnect the car battery, I removed the POSITIVE (RED +) (not the negative, it stayed connected).

Everything got done, but when I put back on the positive, it sparked a bit. I tightened it up, and everything seem fine (no weird sounds or glitches).

I am terribly worried (and

at myself) now. Did I cause hidden damage, by undoing the POSITIVE first (not the negative)?

I don't think that would cause any issues … you should have removed the negative before connecting positive and then connect negative. But a little sparks are common whether you disconnect positive or negative. Don't worry about it 😊

xxfinity · 04-26-2022, 05:07 AM

freespirit is correct. There is always a spark when you connect the battery.

Since the car body is grounded, if you were to loosen the positive terminal with a metal wrench and the wrench touches the car body, it would short and cause quite a spark. Potentially damaging the battery and welding your wrench to the car body, to wherever it touched. Happened to me once lol. But it was on a car without a AGM battery.

Sounds like you that didn't happen to you. So you all good.

Th3Walrus · 04-26-2022, 06:23 AM

Quote:

Originally Posted by xxfinity

Since the car body is grounded, if you were to loosen the positive terminal with a metal wrench and the wrench touches the car body, it would short and cause quite a spark. Potentially damaging the battery and welding your wrench to the car body, to wherever it touched.

Which is why you should always remove rings when disconnecting the battery. If your ring becomes the ground between the wrench and the car body, the ring heats up and burns your finger.

xxfinity · 04-26-2022, 10:23 AM

TRUE. Never actually thought about that before lol.

derek.megyesi · 04-26-2022, 08:04 PM

Thanks, everyone for the advice. I have some more interior work to do, so I will make sure to unplug the NEGATIVE going forward.

04-25-2022, 04:01 PM	#1
derek.megyesi M-Experienced 48 Rep 198 Posts Drives: 2024 BMW X5 xDrive50e AWD SUV Join Date: Jun 2018 Location: Bellevue, Washington iTrader: (1) Garage List 2024 BMW X5 xDrive5 ... [10.00]	Accidently unplugged POSITIVE first (not negative) Hi all, I am terribly nervous. I had to do some maintenance on my 430XI (F36) yesterday and in my haste to disconnect the car battery, I removed the POSITIVE (RED +) (not the negative, it stayed connected). Everything got done, but when I put back on the positive, it sparked a bit. I tightened it up, and everything seem fine (no weird sounds or glitches). I am terribly worried (and at myself) now. Did I cause hidden damage, by undoing the POSITIVE first (not the negative)?
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04-26-2022, 05:07 AM	#3
xxfinity Enlisted Member 4 Rep 46 Posts Drives: 2014 BMW 435xi Join Date: Aug 2018 Location: Toronto, ON iTrader: (1)	freespirit is correct. There is always a spark when you connect the battery. Since the car body is grounded, if you were to loosen the positive terminal with a metal wrench and the wrench touches the car body, it would short and cause quite a spark. Potentially damaging the battery and welding your wrench to the car body, to wherever it touched. Happened to me once lol. But it was on a car without a AGM battery. Sounds like you that didn't happen to you. So you all good.
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04-26-2022, 10:23 AM	#5
xxfinity Enlisted Member 4 Rep 46 Posts Drives: 2014 BMW 435xi Join Date: Aug 2018 Location: Toronto, ON iTrader: (1)	TRUE. Never actually thought about that before lol.
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04-26-2022, 08:04 PM	#6
derek.megyesi M-Experienced 48 Rep 198 Posts Drives: 2024 BMW X5 xDrive50e AWD SUV Join Date: Jun 2018 Location: Bellevue, Washington iTrader: (1) Garage List 2024 BMW X5 xDrive5 ... [10.00]	Thanks, everyone for the advice. I have some more interior work to do, so I will make sure to unplug the NEGATIVE going forward.
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