[wall_nut]

Anyone have a TIS guide for this or is it as straightforward as disconnecting the negative terminal? Where is the 12v battery?

[wall_nut]

Well I've found two 12v batteries under the rear trunks accessory tray. Is disconnecting the larger battery enough or do both need to be disconnected when working on things?

I'll be disconnecting some connections inside of the center console / gear shifter and want to remove power before doing so.


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[wall_nut]

Figured it out through trial and error. All you need to do is disconnect the negative lead for the large primary 12v battery and then wait for the car to go to sleep (maybe 5 minutes?). Disconnecting the lead does not immediately defeat power to the car as the high voltage battery powers the vehicle through an inverter. Once the car goes to sleep...it does not wake up or respond to anything. Maybe there's a way to force it off but I didn't want to lock the vehicle as I needed it fully open to work on it.

[SmartSaves]

Keep the hood open to turn off the 48v system (if 45e has this tech). Then disconnect the negative terminal. Never manually close the tailgate when the negative terminal is disconnected 😀

[wall_nut]

The 45e doesn't have the mild hybrid tech. I did figure out you just have to hold down the radio power button for a few seconds to shut everything down after disconnecting the 12v battery. Only the primary 12v battery needs to be disconnected.

[SmartSaves]

Good to know. Interesting that 45e has two 12V batteries (92 and 50 Ah) at the back. Is there another battery inside the engine bay?

My 21 X5 40i with mild hybrid and DHP has threes batteries:

1. Engine bay (lithium).
2. Inside trunk (same as yours).
3. Inside the rear fuse cubby, at the bottom (this is probably for active stabilization), can't read the battery label because it is inside a housing.

[wall_nut]

Originally Posted by SmartSaves

Good to know. Interesting that 45e has two 12V batteries (92 and 50 Ah) at the back. Is there another battery inside the engine bay?

My 21 X5 40i with mild hybrid and DHP has threes batteries:

1. Engine bay (lithium).
2. Inside trunk (same as yours).
3. Inside the rear fuse cubby, at the bottom (this is probably for active stabilization), can't read the battery label because it is inside a housing.

I don't believe there's any batteries up front. There's lots of hefty wiring connections up there that are running to and from the 12v and HV batteries. EME I believe it's called. Electrical Machine Electronics. The brain of the system connecting the charging port, batteries, and electric motor together. at first I found it odd that there are two 12v batteries for a PHEV. Now I assume the small 12v is necessary since driving in hybrid mode can cause frequent ICE starting.

[wbeemer]

Originally Posted by wall_nut

Figured it out through trial and error. All you need to do is disconnect the negative lead for the large primary 12v battery and then wait for the car to go to sleep (maybe 5 minutes?). Disconnecting the lead does not immediately defeat power to the car as the high voltage battery powers the vehicle through an inverter. Once the car goes to sleep...it does not wake up or respond to anything. Maybe there's a way to force it off but I didn't want to lock the vehicle as I needed it fully open to work on it.

Thank you for the post. Could you give some instructions on how to open the accessory tray? I have some difficulty opening it. I also have the 45e.

[igorlipov]

Is it safe to disconnect both batteries in 45e without computer complications?

[Sh0ty]

Originally Posted by wbeemer

Thank you for the post. Could you give some instructions on how to open the accessory tray? I have some difficulty opening it. I also have the 45e.

Super easy, just remove the 6 plastic fasteners, then lift the leading edge and slide to the right to clear the gas strut.

To remove the fasteners, use a trim removal tool (or flathead screw driver, if you’re into that kind of thing) to lift the center portions, then simply pull with your fingers.

[E91toG05]

Originally Posted by igorlipov

Is it safe to disconnect both batteries in 45e without computer complications?

Never saw an answer to this. Wanted to confirm that to do work on a 45e, you can disconnect the larger 12v battery negative terminal, wait 5 minutes and then good to go. Any concerns when powering her back up? Going to install a powered sub and want to disconnect 12v power first. Thanks.