[JamesCook16]

I've got a 2017 440i with to my knowledge an OEM BMW lead battery and the factory 180a (if I'm not mistaken) alternator. I'm going to add a sub and amp with the technic harness. Anyone know how many watts the stock electrical system can handle? I'm trying to do this as clean as possible and don't want to have to play with a bass knob and constantly monitor voltage, I just want a nice clean hands off install. TIA

[NealfromNZ]

I’ve had warning once from the BMS system. ( pull over as BMS may disconnect on cluster )



Half flat battery under charge, music pumping amp likely to be drawing 60- 80 amps. But also running lithium 69a/h battery which pulls the current under charge.

On a 90 a/h amg battery I don’t think it charges at the same rate so likely more current available from alternator for system.

I wouldn’t go class a/b with high current requirements with the F3x due to battery management system.

Otherwise, stock door & parcel shelf is .75mm2 cable so 200 - 250 watts peak at 4 ohms.

Underseat has 2.5mm2 cable so no worries with any aftermarket underseat woofer.

Anything more than 80 amps on the ve+ go direct to battery for amp feeds.

[JamesCook16]

My buddy who knows more about systems than me is recommend a 2000w amp wired at 2 ohms for 1450w rms powering 2 750w 10inch subs. We would be pulling the power direct from battery. He recommended I check the forums because he isn't familiar with some of the oddities of BMW. Based of running voltage and amp output he thinks that will be ok, that sound right? I just wanna double check before I dive in

[JamesCook16]

The amp is the Sundown SAE-2000 class D monoblock with 2 750w SA-10 classic dvc 2ohm for refrence

[NealfromNZ]

Class D is the key on sub bass at those power levels.I think you’d be fine.

I’m running a 1.2k RMS system on class D/G. Has about a 90% efficiency ratio on the PSU so easier on electrical system.

Other than that one off where I’d done some in garage tuning of the dsp and ran battery down to 30% so had that BMS warning once as per my first post.

[NealfromNZ]

Worth a read, background on electrical system.

https://www.bimmerpost.com/goodiesfo...ectronics1.pdf

[JamesCook16]

Thanks I'll give it a read