grounding points

[djrlittleton]

what are the best places to ground amps in a 93 318is

[carstereopro]

Couple questiosn first.

What are you running for amps, and where are they?

Your battery is under the hood, right? (I may be wrong on this one)

[djrlittleton]

2 mtx amps in the boot battrey under hood right 0 gauge cable in. stinger rcas

pioneer 7900 usb headunit
mtx 4.1 components
mtx preboxed twin 10"

[carstereopro]

If you're running 1/0 ga to the trunk, you need to upgrade all of the factory ground leads to 1/0 ga as well. Battery to chassis, engine to chassis, alternator (errr.....generator in Europe I think) case to chassis .

Then you want to find a clean location in the trunk (boot) near the frame where the metal is thickest and there is nothing you can accidentaly puncture, damage or drill into. Scrape all the paint away and clean all paint dust and residues away.

If you can, use a nut and bolt with two fender washers and a lock nut. Bolt it up tight (may require the help of a friend), and use rubberized or asphalt undercoating to protect the bolt and the grounding location. If you cannot bolt through, I like using a grounding block like Streetwires "GT0" or "GT4" depending on the gauge wire I require to ground my amps. YOu still need to clear off the paint, but three self tapping screws will bold it securely. (don't forget to use the undercoating.)

If your battery was in the trunk, I'd ground it to the same location the battery was grounded, and upgrade all the factory ground wires as well.

[djrlittleton]

thanks man still altenator over this side off the ocean i will try why do have to upgrade the grounds on engine?

[carstereopro]

Originally Posted by djrlittleton

thanks man still altenator over this side off the ocean i will try why do have to upgrade the grounds on engine?

Well, a chain is only as strong as its weakest link.

Here is the not so simplified explanation:

Electricity basically follows a cycle (called a closed circuit), a break in the cycle stops the flow of electricity (called an open circuit).

If you could imaging a hose of uniform width with water flowing in a circle. Imagine a pump placed in-line with the hose where all the water flows through the pump and back out into the hose. This creates a cycle which represents the electron flow in an ideal circuit.

The hose represents the flow path (wire, chassis, terminals, etc), the pump represents the Battery, the power source running the pump would represent the alternator, and the water represents the flow of electrons (electricity)

Now if you were to pinch the hose to restrict the flow, you would create turbulence (resistance in electricity), where the water flow is slowed. This represents a "weak link in the chain that is electricity".

The flow of electricity in a circuit has to be equal in feed and return, or else the limit of the flow is limited to the most restricted point of flow.

Hows this for simple again.....

If you can fill a pool with a garden hose, but drain it at the same time with a fire hose, it'll eventually go empty. If the feed and drain are the same size hose, you'll have a constant level in the pool.

So if you're using 1/0 to "feed" current, but only "return" the current flow to the battery through a 4ga, you might as well be running a 4ga feed as well, since that is the limiting factor in the circuit (the weakest link).

If you can feed with 1/0, and return with 1/0, the demands of the amps should be more easily met by the battery. (in a perfect world)

So to answer your question, because in a vehicle with many different grounding paths to the battery and alternator, it is better to upgrade all grounding devices and be safe, rather than be sorry.

Hope that explains it.