Battery protection
Regards,
paul...
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The underhood battery is (as you face the opened hood with your knees touching the bumper) on your left side all the way in the back near the firewall. It is covered with a black blastic box. It is small & cube like in size.
The battery in the trunk is the one that starts the cars and runs everything else. The small battery in the engine compartment is a standby battery to keep the SBC electromechanical braking system powered in the event the main battery's voltage drops below a certain level.
You need to know what the current draw is for both amps (output wattage into speakers doesn't help), and then find a vacant position in the fusebox that has a rating higher than your amps total input current. Then you can use that to power your system.
The bottomline is that there's a battery control unit (BCU) that controls the draining and charging of both batteries and you cannot bypass this.
I suggest you post on the audio forum for help to see what otehr people have done (successfully).
Regards,
paul...

Mine did the same thing while driving on the highway. I dont have an electrical mods done to my car except for lowering it via star diag done by the dealership. This is not becoming a coincidence....
Edit: Note that this is f/an '04 E320, see paulv post below....your's may be there.
Last edited by starbrite; Jan 18, 2007 at 11:23 AM.
You have to do all that on your 04 E320? On my 03 E320, I just remove the screw on the front of the combo filter cover (on the wheel well) and pull up on the cover as it's hinged -- I've already replaced my combo filters a couple of times and also replaced the aux battery ($125 at the MB parts counter).
Regards,
paul...
Regards,
paul...
Go to http://www.mercedestechstore.com and look at the training files. Under the W211 stuff, there's a pdf file about the dual battery setup. This will provide you info so that you can either forget the whole idea or find some way of hooking up your amps. The file is too big to post here. You should really solicit advice from the Audio section on this forum -- maybe someone has [successfully] done this before.
Keep in mind that the electronics in these cars are very expensive.
Regards,
paul...
Turned off the ignition and measured the battery CCV (closed circuit voltage) and read 11.93 volts,
which indicates the battery was 75% discharged. As soon as I started it, the message went away.
It had been about 10 days since I last drove it, but that still seemed a bit extreme to me.
Edit: BTW, if any of you aren't aware of the reference voltages for a battery's charge state, here they are :
12.00 volts 25% charged
12.35 volts 50% charged
12.50 volts 75% charged
12.75 volts 100% charged
Note that these are Open Circuit Voltages, that is battery ground disconnected.
CCV's (cables connected) will be slightly lower but are still a valid reference for a battery's charge state.
Last edited by starbrite; Jan 22, 2007 at 01:45 PM.



