M5POST
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read

Go Back   M5POST - BMW M5 Forum > F10 M5 Forum > Navigation, iDrive, Audio, Video, Bluetooth, Phone, Coding

Post Reply
 
Thread Tools Search this Thread
      10-24-2018, 04:14 PM   #1
msq123
Private
United Kingdom
22
Rep
79
Posts

Drives: BMW M5 F10 2014
Join Date: Dec 2017
Location: London

iTrader: (1)

Audio upgrade - sufficient power?

Straight of the bat, apologies for the long postÖ

I have some noob questions about the capability of OEM battery and alternator to support my audio set up. I will try and break down what I have and how much I think every part consumes and my calculation for experts here to review.

I have BMW M5 F10 running 676 hi fi system with following changes:

a) stock amp driving rear 2 speakers only so I believe it is only drawing 25x2w (am I right in thinking if I am not using any other channel there is no more power usage?)

b) Audison Bit 10 connecting the above amp with my 2 aftermarket amps. I am not sure about power usage of this processor?

c) JLAudio XD400/4 v2 amp (75w x4 @4 ohms) driving door speakers (Focal K2 10cm) and Focal iFBMW v2 sub

d) Hertz HCP-1D monk amp (700w @2 ohm and 380w @4 ohm driving Hertz HX250 sub (400 watts). I was thinking of running this at 2 ohm, dialed down for lower power sub but I am concerned if 700w is too much for the carís electrical system to handle. I will use 380w below in my calcs

Stock amp - 25 x 2 = 50w
Multi channnel amp - 75 x 4 = 300w
Mono sub amp - 380w

Total = 730 watts

Account for 30% inefficiency gives me power draw of 1043 watts (730/0.7)

Using 13 voltage to get to amp hour - 1043/13 = 80Ah (this is peak volume draw)

or worst case scenario of 12v = 1043/12 = 87Ah

So, my question is regarding the combined output of carís alternator and battery. I am not entirely sure but from what I found on the internet alternator is 210Ah and battery is 95Ah.

When the car is up and running I understand that up to 60% of alternator output could be used by the car so I am left with 40%, i.e., 84Ah plus batteryís powe, therefore, I think I should be fine with the set up.

1. Could anyone familiar with carís power management system have a look and check if my calculations are right and I can proceed with this set up without any risk to any component due to insufficient power?

2. Am I right in running my mono amp at 4ohm instead of 2ohm thereby saving about 320w (or 450w accounting for inefficiency). I donít think I have enough power to run at 2 ohms and I should not be using battery when the car is running. Alternator should suffice my needs in most cases without drawing power from the battery.

Thanks
Appreciate 0
      10-28-2018, 02:22 AM   #2
boots
Curve Thrasher
boots's Avatar
506
Rep
3,717
Posts

Drives: 2013 Bmw m5..White/Blk.
Join Date: Nov 2012
Location: Cypress Tx

iTrader: (0)

wish I had the answer for you but I don't. hopefully someone here has done a upgrade.
__________________
2013 Bmw M5-Alpine White/Black-Oem gloss blk powder coated wheels-Expel clear bra-35% tint-Rpi Gtm Exhaust-Rpi Downpipes-Rpi Scoops-Halim Cazimi Performance Tune-KwV3 coilovers

Country run
Appreciate 0
      10-30-2018, 01:23 PM   #3
msq123
Private
United Kingdom
22
Rep
79
Posts

Drives: BMW M5 F10 2014
Join Date: Dec 2017
Location: London

iTrader: (1)

Found some answers on another forum that I would like to share in case anyone looking for something similar.

Basically, I should be able to run my amp @ 2ohms which is 700w without adding new battery or capacitor or any change to power delivery system.

In reality it's more like 550w at 1% THD and 700w at 10% THD. no one wants to hear musics at high distortion levels of 10% for long. This is all marketing bullshit to quote unusable power or with high distortion.

The numbers I used were with the assumption that I will be running the amps at 100% capacity which I am told will never happen for mids and tweeters. They will hardly draw 15% or the rated 75w power.

Subs use the most power but again, 550w or 750w only happens at 20hz frequency which is rare and at full volume. I plan to use crossovers to define ranges for various speakers so I will probably looking at 50% power capacity usage for the sub at most. And lower for underseat subs which I am running through JLAudio at 75w per channel.

Initially, the whole calc and frequency was very daunting but the article in the link below helped me understand how much power speakers will require from the amp at various frequencies.

https://www.audiofrog.com/community/...get-150-watts/


I hope someone finds this useful. Cheers
Appreciate 0
      05-13-2019, 12:05 PM   #4
VinylFrontier
New Member
18
Rep
25
Posts

Drives: BMW M5
Join Date: Mar 2019
Location: Nebraska

iTrader: (0)

I'm looking to add an aftermarket amp for my subwoofer as well. Where did you tie in power at? Did you do it directly at the battery? Or at the fuse box? Any issues with error codes after doing the upgrade?
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 08:41 AM.




m5post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST