Connecting PC directly to battery in X3

Hi,

I have an 2010 X3 and want to power a small industrial PC situated in the trunk. It pulls less than 5 amps and I have a www.mini-box.com M2 ATX PSU in front so it will shut down on key-off and is protected by a fuse. I want the cables hidden and therefore don't want to plug it directly into an accessory outlet. Also, I expect to add additional devices in the future and plan on installing 12 ga cables with a 20 amp fuse which should take everything I plan to throw at it plus some.

My question is can I power it directly from the battery under the trunk (boot) panel? I have read that many modern vehicles have a battery (or power) management system so I shouldn't connect directly to the battery as it will bypass this module and prevent it from controlling the charging correctly. I understand that I should not connect directly to negative terminal of the battery so I'm only concerned about the positive battery terminal. I can't find any information as to whether there is a battery management module on the '10 X3 and if so if it is on the positive terminal.

I have heard that jump points are the dealer and manufacturer recommended way to power 3rd-party devices but as far as I know they are only available in the engine compartment and I don't want to route cables that far if I don't have to. 3rd party suppliers such as those on etrailer.com still mention connecting accessories such as trailer lights directly to the battery.

Thanks in advance for any information

Ian

Ian,

Will it keep working when the engine is off or not?

Originally Posted by kenza

Ian,

Will it keep working when the engine is off or not?

No it is switched by the ignition. The M2 ATX power supply http://www.mini-box.com/M2-ATX-160w-...=8&category=13 senses the ignition key. When ignition turns on the PC is powered and a signal is sent to the front panel switch thus booting the PC. After the ignition is sensed to be off it keeps the 5V standby rail on the PC powered for a period of time to let the PC completely shutdown. In case you are interested I tapped the ignition line going into the BMW navigation system (purple/white) to use as ignition sense.

Originally Posted by imilstea

I have an 2010 X3 and want to power a small industrial PC situated in the trunk. ....

My question is can I power it directly from the battery under the trunk (boot) panel?

Have you considering just using the 12V outlet in the trunk by attaching your feed wire to the back of it so that it is concealed?

Not sure about your 2010, but earlier models had constant power (not ignition-switched) to all 3 outlets.
That could have changed in later years.

Originally Posted by Supercourse

Have you considering just using the 12V outlet in the trunk by attaching your feed wire to the back of it so that it is concealed?

Not sure about your 2010, but earlier models had constant power (not ignition-switched) to all 3 outlets.
That could have changed in later years.

That's a possible backup as it is not switched on the 2010 and is on a 20 amp circuit. From time to time (on a temporary basis) I will be running an inverter from a 12V outlet from so I'm concerned about overloading that circuit when used in conjunction with the permanently installed hardware.

If you connect it directly to the battery, and it will be off when the ignition is off, there should be no problems with the power monitoring system.... Try it and let us know

Originally Posted by kenza

If you connect it directly to the battery, and it will be off when the ignition is off, there should be no problems with the power monitoring system.... Try it and let us know

there are 2 main main junctions of the battery, one on the exsplosive removal side and one that powers important subsystems that are needed post roll over. there are junction blocks that you can attach bar fuses to if you want to add a circuit on the explosive side of the circuit.