N7turbo
2023 CX-5 2.5T ... 2024 MX-5 RF GT
That is seriously useful for when I can't use my Kill-a-Watt.
But note that you really want to use the Kill-a-Watt for accuracy when possible. I wouldn't trust a clamp meter 100%.
Grounding Cylinder Head Test Results (2024 CX-5 Turbo)
- Thread starter AL Cx5
- Start date
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- Tags
- cylinder head ground wire
But note that you really want to use the Kill-a-Watt for accuracy when possible. I wouldn't trust a clamp meter 100%.
I agree about accuracy with the Kill-a Watt but I think it's super useful for tracking usage and computing cost. The line splitter works good enough for my purposes, at least for now. I have however contemplated buying a KaW a few times in the past but couldn't justify it.
*** PSA -- as of now (12:12 am EST) Amazon still has the line splitter marked down to $12.06. I only mention this because of Amazon's habit of suddenly raising prices after a brief markdown. I see this behavior a lot on another forum where someone posts a seriously great price on an expensive tool and the deal is discontinued in minutes. Seems Amazon Warehouse Deals does this a lot. Well, I won't belabor the point and this is getting off topic anyway.
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
Just ordered that spitter...
N7turbo
2023 CX-5 2.5T ... 2024 MX-5 RF GT
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
I have this one too. Works fine. The splitter will be a convenient way to quickly check AC.
N7turbo
2023 CX-5 2.5T ... 2024 MX-5 RF GT
What situations would you use it in where the Kill-a-Watt won't work?
- :
- 2023 CX5 turbo
Got the meter and using the valve cover bolt like @AL Cx5 photo I get barely any amps less than 1amp. that is with head lights on and fan turned to high if that makes a difference. but then I switched to dc and got over 17A so I a guessing it needs to be on dc? or maybe I am in way over my head. 
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. Koko_Bandit
'23 CX-5 CE
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- '23 CX-5 CE
Yes, the electrical systems for cars are DC. You were measuring the fluctuation in current when on the AC setting.
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
Got the meter and using the valve cover bolt like @AL Cx5 photo I get barely any amps less than 1amp. that is with head lights on and fan turned to high if that makes a difference. but then I switched to dc and got over 17A so I a guessing it needs to be on dc? or maybe I am in way over my head.
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Nice going! X2, cars are DC...
Snappy looking meter compared to shop worn one...
Now you landed it in the correct place.
Do the drivers side for bonus points!
BoomerZoomr
'25 CX-5 Signature '19 Mazda6 Signature
Playing Devil's Advocate here… to get full use of installing these additional large gauge ground wires, wouldn’t you need to replace the negative wire on the battery with something larger?
Ok. I have another data point. 2025 CX-5 PP non-turbo with 4 seat heaters, headlights, and AC on.
41 amps current from cylinder head to ground.
25 amps through battery negative ground.
0.06 amps from throttle body to ground.
I will move the throttle body ground to the transmission next. The throttle body ground carries no current!
41 amps current from cylinder head to ground.
25 amps through battery negative ground.
0.06 amps from throttle body to ground.
I will move the throttle body ground to the transmission next. The throttle body ground carries no current!
Attachments
Nope.
The negative battery cable isn't part of the circuit that includes the new ground wire(s). The positive cable is, though (or is it the positive side of the alternator?).
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AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
You have large diameter ground cables and landing it on top of the battery ground is like it's connected to the battery. Excellent install.Nope.
The negative battery cable isn't part of the circuit that includes the new ground wire(s). The positive cable is, though (or is it the positive side of the alternator?).
Pro install, not what I did, lands the ground on the battery connector. To do that we would need to change out the connector to something like a military style connector. I have military style connectors on my diesel pickup. They are heavy duty dudes and have a convenient place to add additional wires. It would be an upgrade. I keep a few of these in my parts bin. Maybe I'll cut that tiny OEM connector off and put a lug fitting in it's place.
Like I said above, we land the grounds ON the battery from our coil harness on the race car. But it's demanding 300 mJ x 8 cylinders vs 50 mJ on our Skyactives. We have massive connectors on this 16v lithium battery. We are running enough current, that I changed out the required external power off switch from copper to silver contacts.
Got to say, I'm lusting over these shiny new clamp style multimeters. Maybe mine will quit working one of these days...
Cummins 5.9 Diesel, passenger side battery ground. Pic is an example, not my truck...
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I see. That particular cable is going to move anyway since it's connected to the throttle body.
I was surprised to see 41A on my meter. Those heated seats must be the reason!
With that much current the bigger wires have to be a good upgrade!
BoomerZoomr
'25 CX-5 Signature '19 Mazda6 Signature
You stumped me on that one… I thought to complete the circuit on an automobile DC system, everything had to come back to the battery negative terminal.Nope.
The negative battery cable isn't part of the circuit that includes the new ground wire(s). The positive cable is, though (or is it the positive side of the alternator?).
You may be correct. I'm not entirely sure thats the case when the alternator is running. I'll try a larger battery ground to see if there's a current increase.
AI says:You may be correct. I'm not entirely sure thats the case when the alternator is running. I'll try a larger battery ground to see if there's a current increase.
While the alternator is the source of power when the engine is running, the battery negative terminal is technically the ultimate system ground point, as it serves as the reference 0V baseline for the entire vehicle. However, because high alternator current must return to the battery, a solid engine-to-chassis-to-battery ground path is necessary, often making the alternator mount a "peak" ground point for current flow. [1, 2, 3, 4, 5]
Key Considerations:
- System Grounding: All negative circuits, including the alternator housing, connect to the chassis and engine, which are grounded to the battery negative terminal.
- Running Engine: When running, the engine block (and alternator case) often serves as the most efficient, high-current ground path.
- Battery Negative: The negative battery terminal remains the ultimate, central grounding point for the whole system, even if the alternator bracket is the "most negative point" due to voltage drop.
- Best Practice: Many high-output charging systems benefit from running a ground cable directly from the alternator housing to the battery negative post for superior grounding. [1, 2, 3, 4, 5, 6]
I stand humbly corrected!
AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
Yes 41 amps is impressive amount of energy. I'm surprised the NA TB is even less than the turbo. I decided to leave my TB ground for now.
Did I read that you have are getting ready to ground your trans? I removed the airbox and grounded to the top of the transmission to the chassis. I didn't take any pictures. I did find measurable current flow through the ground. Not as much as the engine but more than the TB.
Report back please, your findings on the transmission ground. It might be a subtle change. Faster up and down shift stuff.
That new toy looks familiar (LOL). Your reading of 17.68 A on that wire confirms the validity of the 15A and 18.9 A readings I got under same conditions as yourself (headlights on and blower on high. It'd be interesting to see what you measure on the wire attached from the battery negative terminal to the "fender". I think I measured around 25A. I don't think that AL Cx5 knew what he was starting when he first introduced this subject. Soon Amazon is going to be sold out of clamp meters and heavy gage wire.got the meter and using the valve cover bolt like @AL Cx5 photo I get barely any amps less than 1amp. that is with head lights on and fan turned to high if that makes a difference. but then I switched to dc and got over 17A so I a guessing it needs to be on dc? or maybe I am in way over my head.
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AL Cx5
2024 CX-5 Prem Turbo Tuned Lowered Forged Wheels
This is ALL great to see others getting similar results.
Now the real proof it better mileage and/or better performance. I used to carry a 10mm socket wrench to remove the grounds from the chassis/fender on trips. My wife is an angle, btw. LOL
Best practices, hand calculated, same pump and don't squeeze more fuel into the tank. Overhead mileage is a good estimate but the Lie-O-Meter is off up to 2 MPG on my ride.
Now the real proof it better mileage and/or better performance. I used to carry a 10mm socket wrench to remove the grounds from the chassis/fender on trips. My wife is an angle, btw. LOL
Best practices, hand calculated, same pump and don't squeeze more fuel into the tank. Overhead mileage is a good estimate but the Lie-O-Meter is off up to 2 MPG on my ride.
