EFI Wiring Basics: The Difference in Clean and Dirty Power & Grounds: Tech Tip Tuesday

[@adamelwood7768]

I actually had the chance to help Brad for a couple days when he came to wire up my brothers Nova! Heck of a dude and i definitely learned a lot from him. Glad to see he is still at it. Heard he is pretty good at building an engine too!

[@cullen3]

Brad, it is ok to smile.

[@mrmatt2525able]

Very interesting stuff. Good tips! in my race car I have a remote battery in the trunk, I ran a big wire up to the starter, then all the dirty power right to the starter, and I ran the alternator back directly to the battery so you don’t have a back feeding when you kill the car with the bumper switch, and I ran a clean power wire from the battery to a lug under the dash for all the clean power needs, and have a relay in the back the disconnects the clean power when the bumper switch is open so you still have it directly to the battery and nice and clean voltage

[@ton73z28]

It is hard to explain the differences between battery ground, frame ground and (especially with electronics) system ground to non electronics car people (Well with the old guys I work with). 😀 Good work guys.

[@windward2818]

Dirty power, in the contexed of this install, refers to power circuit (+12V Battery +) common circuit impedance or ground (Battery GND) common circuit impedance, which can be though of as different circuits sharing a common wire, either a power feed or a power return. When a load demand (switched on or off) changes current through a shared wire impedance (resistance and reactance), the wire voltage drop and reactive effects with be superimposed (shared) with the other circuit because they both use a common wire. In other words, to keep things electrically quiet (meaning clean power) do not mix currents. Keep the power feeds and returns separate so the circuits cannot influence each other in unforeseen ways when loads are activated. Also, in keeping the system quiet you would like to run the power feed and the power return directly next to each other (ideally twisted) to minimize any coupling or EMI effects.

[@darwinmcreynolds3278]

I i didn't now that it was called dirt power but now i do i new not to run sit together but thanks for the refresh be safe and have fun

[@tillman40]

So Brad...have any time slots next week?

[@dewizle5026]

Nothing against Brad I'm sure he's good at what he does. But once the car starts the ECU is being powered by the Altenator/ Generator unless the ECU has it's own isolated Battery and is in constant discharge the ECU is getting dirty power from the Alt. A well-designed ECU will have a circuit build into the ECU to clean up and smooth out the current before it is delivered to the CPU and delicate electronics. As he said in his home power analogy an older tube-type tv would show when a load added to the circuit it was but new TVs don't because they have current smoothing and filtering circuits built into them. And saying you have wire the ECU directly to the battery is setting someone up to burn their car down because if the ECU doesn't have switching circuits connected to the ignition switch the car would never shut off after you started it. The better advice is to make sure your ECU and delicate electronic circuits don't have and large draw items or motors on them and for added safety add a current/Voltage filtering circuit between the ECU and where ever it gets power Also make sure you have Solid Grounds as close to zero ohms between your grounding point and the negative terminal at the battery no matter how far it is from the battery.

[@1000travisz]

Yes but the battery is still acting as a filter, it will level out any voltage spikes or drops. That is the idea behind hooking computers directly to the battery.

[@1320wolf]

Any low current voltage spikes (noise) won't make it thru the battery, because the battery will absorb them (capacitance).....that is my understanding at least

[@adriancampos382]

like it says on the instructions on the holley ecu “CONNECT DIRECTLY TO THE BATTERY” And people yet still don’t follow the damn directions

[@dewizle5026]

@@1320wolf A battery is not a capacitor it can only absorb the votage it's rated to your ecu is hooked up the same positive pole your starter and alternator is hooked up to if your battery is rated 12.5 volts 350amps and your starter draws 360 amps your ecu will see a voltage drop when the starter is running if your Alt is defective and puts out 18v your ECU will see 18v volts and your battery wont live long but your ECU will survive because of it built in voltage regulation circuit. In 35yrs of Aviation and Automotive work I have only heard the terms AC/DC Regulated and Unregulated power. drity power is not a term used in any of the professional setting I've worked In.

[@scottsingleton2655]

Awesome video good information

[@Gotboost428]

Thank you

[@tadwiltman4875]

If they all say to run power and ground direct to battery... how the hell do you do a main shutoff?

[@ryanchacon2005]

im having electrical spikes when i turn my key to power on everything. Idk where to start looking for problem

[@ClintonC1991]

maybe this is a dumb question, but if I have the battery in the back and run the main power wire to the front into a (blanking on the word) connector thing. Is that clean power or do I need to actually run everything back to the back directly to the battery?

[@jaredtillman6247]

Is there any benefit to changing a factory harness to provide clean power and grounds? I have a lightning that's modified a good bit and I have improved my power and ground wires but it's all grounded to the firewall with a large gauge wire to the battery. I could send the ECU ground and power direct to my battery or some posts.

[@brianstechtips5721]

What if you don't want a million things going to the batter? How do you fix that?

[@echo71702]

How do you do this nhra legal??? Holley says wire the ecu straight to the battery, nhra says only thing that can be on the battery side my the kill switch is the alternator

[@toddpeck261]

Would a distribution block fed directly from the battery be a dirty power source? or clean?

[@toddpeck261]

Sorry the video just answered my question.

[@tillman40]

Whose the FL guy to go to for wiring

[@jasonjames5153]

KSR Performance and Fabrication

[@yaright1635]

wow i cant fix any of this easy