Routing a power cable from battery to boot

[Shando]

Hi Ive just bought a subwoofer/amplifier combination and Im looking to route a heavy duty cable from the battery to the boot to power the sub, Do I actually need a dedicated run like this or can I tap off anywhere else for the power, the amp is 100w rms


If I do need to route the cable, can someone tell me the best way to route it, as I aint got a clue.


Thanks for all your help

[Shando]

Sorry forgot to mention the car is E34 525i se

[Mr. BILL]

You will need to run a seperate power cable directly to the battery. You forgot to mention what year your car is, so if the battery is under the rear seat, that's easy. Just tie into the + terminal to your amp and you're set. If it's in the trunk that's easy too, pretty much the same.

If the battery is in the engine bay, that's a little more complicated. You will need to remove the felt seal that runs around the doors, pull up on the plastic thresholds on the door sills, remove the kick panel (all this is on the passenger side) and remove the rear seat. Look behind the "black box" on the passenger side.. You should see a rubber plug about the size of a silver dollar.

Take an x-acto knife and pierce the rubber plug in the center. You only need to make a small slit, just big enough to poke the power cable through (it needs to be half the size of the cable to insure a sealed fit). Push the cable through the hole into the car from the engine bay side. Then, reach up from the kick panel area and pull it into the car.You can apply some silicone around the cable to seal it, but it's high enough not to worry about water leaks.

Run the cable behind the kick panel, under the carpet along the doors under the rear seat and out through a hole in the wall seperating the trunk from the cabin.

I hope that made sence.

[Shando]

Hi Mr Bill - The car is a 92 European UK model (RHD) and the battery is in the engine compartment

Is there not a heavy + cable under the seat that I could take a tap out of? I read somewhere that this might be the case

If not then your instructions were great - sounds like a little bit of work - but hopefully I will get there without wrecking something!

Thanks again





You will need to run a seperate power cable directly to the battery. You forgot to mention what year your car is, so if the battery is under the rear seat, that's easy. Just tie into the + terminal to your amp and you're set. If it's in the trunk that's easy too, pretty much the same.

If the battery is in the engine bay, that's a little more complicated. You will need to remove the felt seal that runs around the doors, pull up on the plastic thresholds on the door sills, remove the kick panel (all this is on the passenger side) and remove the rear seat. Look behind the "black box" on the passenger side.. You should see a rubber plug about the size of a silver dollar.

Take an x-acto knife and pierce the rubber plug in the center. You only need to make a small slit, just big enough to poke the power cable through (it needs to be half the size of the cable to insure a sealed fit). Push the cable through the hole into the car from the engine bay side. Then, reach up from the kick panel area and pull it into the car.You can apply some silicone around the cable to seal it, but it's high enough not to worry about water leaks.

Run the cable behind the kick panel, under the carpet along the doors under the rear seat and out through a hole in the wall seperating the trunk from the cabin.

I hope that made sence.

[Julius]

Trust us on this one and run a new cable.

[bjl4776]

Its not too hard, just time consuming. Be carefully when removing trim pieces from the interior, if it feels like your pulling to hard, or it is about to break it probably is. Like Mr. Bill said there is already a grommet from the cabin to the trunk, but im don't know if there is one in the firewall that is big enough. If not you may have to drill a hole, just becareful of wires and hoses and the such. One thing i have found out about running wires through a car, a straightened out coat hanger can be your best friend.

[Shando]

Thanks guys for all your help - Im going to tackle it on Friday - wish me luck

[gvilkelis]

Hi,
I think, that running dedicated cable from the battery is the best and safest option.
And don't forget to put a fuse on this cable somewhere near the battery, for safety too.

I ran power cable from engine compartment to the trunk exactly the same way as Mr. BILL described in his post - he should have posted this a few months ago, it would have saved me from the trouble of discovering this cable path :)))

And you should also consider the cable gauge for your amplifier - the gauge depends on cable length and amplifier power ratings. Here is a nice page about that:
http://www.eatel.net/~amptech/elecdisc/wire.htm

[ktteoh]

folks, does anyone knows here i can get a pictorial guide on this - the url shown is not working anymore.


Hi,
I think, that running dedicated cable from the battery is the best and safest option.
And don't forget to put a fuse on this cable somewhere near the battery, for safety too.

I ran power cable from engine compartment to the trunk exactly the same way as Mr. BILL described in his post - he should have posted this a few months ago, it would have saved me from the trouble of discovering this cable path :)))

And you should also consider the cable gauge for your amplifier - the gauge depends on cable length and amplifier power ratings. Here is a nice page about that:
http://www.eatel.net/~amptech/elecdisc/wire.htm

[Ferret]

No need to run a new line to the battery. There's a 100+amp termination point under the rear seat that I run all my amps off.

This is already fused at the battery end - and wont show any problems with having a high power amp plugged into it.

Why bother tearing up all your carpets?

[ktteoh]

ferret, can you describe to me where this point is?


No need to run a new line to the battery. There's a 100+amp termination point under the rear seat that I run all my amps off.

This is already fused at the battery end - and wont show any problems with having a high power amp plugged into it.

Why bother tearing up all your carpets?

[Ferret]

ferret, can you describe to me where this point is?

It's a little black box with a thick red cable going in each end... will look the same as the one under the hood that the battery cables smaller line terminates inside.

[leicesterboy15]

Does this zap any power when the engine is off? Even if it is remotely controlled by the head unit?

[ktteoh]

ferret, is this the red cable - the fuse inside says 80A on mine - not 100A+.

also if i move my battery to the rear seat and tap my +ve to this cable, would it take the starter motor load during cranking?

http://lh6.google.com/MickeyTeoh/RoPGtra0lzI/AAAAAAAAATM/AkeiqrPKSSE/s400/BMW%20E34%20Back%20Seat%20004.jpg


It's a little black box with a thick red cable going in each end... will look the same as the one under the hood that the battery cables smaller line terminates inside.

[Ferret]

ferret, is this the red cable - the fuse inside says 80A on mine - not 100A+.

also if i move my battery to the rear seat and tap my +ve to this cable, would it take the starter motor load during cranking?

http://lh6.google.com/MickeyTeoh/RoPGtra0lzI/AAAAAAAAATM/AkeiqrPKSSE/s400/BMW%20E34%20Back%20Seat%20004.jpg

I think that's the one - if you take off the plastic cover there should be two bolt points under it...

The cable should be able to cope with 100A+, but is protected by an 80A fuse - your starter can draw anything upto 450Amps on a cold day turning the engine over from stall - I wouldnt plug the starter into that cable, it's just a distribution trunk.

[Ferret]

Does this zap any power when the engine is off? Even if it is remotely controlled by the head unit?

My amp when connected to this point, with the head unit switched off is drawing microAmps - almost nothing.

It'd be a problem if I was storing the car for a few weeks, but I'd expect the vehicles security system to kill the battery first.

If it was being stored I'd leave the battery terminals off...