Main Battery positive terminal

[MBoss_F86]

Anyone know what the two red wires are for ? They are connected to main battery positive terminal. Looks like all F85 F86 does not have them. My car is 2016 F86 X6M

[Qsilver7]

The battery safety switch is attached to the positive battery cable (#2 in the diagram below)…as well as the underfloor positive battery cable (#3 in diagram below) that attaches to the alternator, starter, and positive jump terminals in the engine bay.



For more info about the battery safety terminal and its function (how a pyrotechnal charge separates the battery from the engine bay in an accident…yet the battery still supplies power for emergency functions like interior lights and unlocking the vehicle…read info below:

[Blue By You]

Originally Posted by Qsilver7

The battery safety switch is attached to the positive battery cable (#2 in the diagram below)…as well as the underfloor positive battery cable (#3 in diagram below) that attaches to the alternator, starter, and positive jump terminals in the engine bay.



For more info about the battery safety terminal and its function (how a pyrotechnal charge separates the battery from the engine bay in an accident…yet the battery still supplies power for emergency functions like interior lights and unlocking the vehicle…read info below:

So to jump the battery or flash the ECU or something like that, is it pretty self explanatory when I open the engine bay to find the positive terminal and a ground? I've never looked...

[Qsilver7]

Originally Posted by Blue By You

So to jump the battery or flash the ECU or something like that, is it pretty self explanatory when I open the engine bay to find the positive terminal and a ground? I've never looked...

Yes…if you need to jump or charge the battery…or connect a battery tender/maintainer when coding etc…you don’t have to remove all the stuff covering the battery…just pop the hood and connect to the dedicated pos & neg terminals in the engine bay. If you can’t find them, I believe they are indicated in the owners manual (especially the neg terminal). Sometimes things may not be a true ground…so I recommend not taking a chance and use the dedicated grounding terminal in the engine bay, too.

Also, using the engine bay terminals…if charging the battery…it runs it through the IBS (intelligent battery sensor). If you connect directly to the battery, the IBS is left out of the equation and when the vehicle is powered back up…the IBS can misinterpret the change in the battery and cause check control warnings.

[Blue By You]

Originally Posted by Qsilver7

Yes…if you need to jump or charge the battery…or connect a battery tender/maintainer when coding etc…you don’t have to remove all the stuff covering the battery…just pop the hood and connect to the dedicated pos & neg terminals in the engine bay. If you can’t find them, I believe they are indicated in the owners manual (especially the neg terminal). Sometimes things may not be a true ground…so I recommend not taking a chance and use the dedicated grounding terminal in the engine bay, too.

Also, using the engine bay terminals…if charging the battery…it runs it through the IBS (intelligent battery sensor). If you connect directly to the battery, the IBS is left out of the equation and when the vehicle is powered back up…the IBS can misinterpret the change in the battery and cause check control warnings.

So when coding, would you use a jump starter like this https://smile.amazon.com/gp/product/...A1HTANIN6TP0K2 or a maintainer/tender like you mentioned? (something like this? https://smile.amazon.com/dp/B07W8KJH...NsaWNrPXRydWU=)

[Qsilver7]

Originally Posted by Blue By You

So when coding, would you use a jump starter like this

Since the reason for using a power supply is to prevent the battery from discharging while coding…I personally prefer a battery tender/maintainer that plugs into a wall outlet. I don’t trust jumper battery packs.

I use a BMW branded battery charger/maintainer. You can find them all over the internet…as well as the oem equivalent brands which make the BMW branded charger/maintainers.

[Blue By You]

Originally Posted by Qsilver7

Since the reason for using a power supply is to prevent the battery from discharging while coding…I personally prefer a battery tender/maintainer that plugs into a wall outlet. I don’t trust jumper battery packs.

I use a BMW branded battery charger/maintainer. You can find them all over the internet…as well as the oem equivalent brands which make the BMW branded charger/maintainers.

Makes sense. Some of the NOCO models plug in and have a steady supply mode providing a constant 13.6V and supposedly can even be used as power sources even when battery is absent.

[Qsilver7]

[MBoss_F86]

After research realized these two red wires are from aftermarket amplifier previous owner installed. I unplugged them, taped it off and stuck them under the bumper.