Battery Cable Upgrade
 

I performed what is known as the big three electrical upgrade. I replaced the block to ground cable, the alternator to battery cable, the battery to starter cable, and the battery to ground cable (yes that's more than three). I am not sure of the exact mechanisms behind the upgrade, but I have noticed an increase in my FE. In previous winters I would average an abysmal 15-16 mpg in my Jeep. The last two fill ups I got ~18.5 and 17.2 mpg. That is a definite improvement, especially when factoring in the less favorable driving conditions I face this winter. I would recommend this upgrade to anyone who still has their flimsy OE battery cables.

I doubt very much that the cable mod produced those results, there is just not enough power lost in the OEM-cables.

If for example you go from 16 to 18.5mpg at 100Km/h you are saving about 2l per hour. that's 19kW from the fuel, with 21% engine and 70% alternator efficiencies that would mean you had at least 2.8kW electrical losses in the wires.

The entire electrical load of a typical car is maybe a tenth of that.

The OE cables are pretty low quality in my Jeep. They were also about 22 years old, so they probably should have been replaced anyway. I don't know how important the grounding connections are but in my Jeep they were just flimsy wires. They were upgraded with the cables. And I suppose that I neglected to say that other mods I have done during the last 12 months include roof rack delete, synthetic oil in the front differential, and maybe my CAI. However, I believe that is negated by me doing significantly less highway driving. I see the mpg I am getting as quite an improvement and I attribute it to having new heavy duty battery cables. Even in the weeks preceding my project I was not getting very good mpg.

I attribute very little to your Big 3.

Jeeps are terrible on the highway, so that might actually be benefiting the fuel economy.

CAI won't help fuel economy in the least.

roof rack delete and synthetic oil should help a decent amount.

There's way too many variables going on here to make any proclamations of fuel efficiency improvements.

I know that how I am presenting this is not very scientific, however my fuel economy is definitely higher than the 6 weeks preceding my upgrade. I had all the mods I noted and the weather was just as cold. Others also report an improvement in mpg after doing the big three upgrade.
It makes sense to me as why this could be, because the spark plugs require electricity to ignite the air/fuel mixture in the combustion chamber. Something important that I should have noted in the first post is that I do not have the OE cap and wires. I have a mild performance set with my plugs gapped larger than stock.

I once had a pinched nerve due to a pulverized L5-S1. The chiropractor said he believed I could be rehabilitated if I saw him for "adjustments" 40 times over the course of 2 months.

Instead of doing that, I did nothing and my back got better over the course of 2 months. Had I completed the 40 adjustments, I would have attributed my healing to the so-called doctor.

My point is that there's too many variables at play to even suggest a result was achieved by a particular action.

It's possible it did improve fuel economy, and it was probably a worthwhile upgrade if the wiring was as poor as you say.

That said, it didn't give you a 12% fuel economy increase. It's not mathematically possible as Jakob alludes to.

If ignition performance were really poor, it would trigger a CEL.

Roof racks can make a huge difference though.

They weren't necessarily falling apart, but they weren't great either. There are lots of variables in play which are hard to measure. It is kind of hard to do ABA testing most of the time, so I try to deduct what I can from my fill ups. I suppose I should pay attention to confirmation bias. That being said, I think they did make a difference.

The roof racks did make a nice difference when I took them off. I think it was about ~1mpg.

That's fair to say it probably wasn't 12%. I think I do remember reading that larger spark plug gaps require more electricity to maintain. I did gap them larger because I've seen sources saying that a larger gap will cause better combustion, but it isn't very clear if I've seen an improvement in FE because of it.

He doesn't gain MPG from freeing up wasted electricity; he restores it from having better signals from his sensors, better spark and the like. Just cleaning the ground connections is usually enough, but replacing things would freshen them up as well.

Cleaning grounds is a normal practice in the geo metro community. It made one heck of a difference to my Miata, and my Ranger was doing all sorts of weird things before I cleaned it's grounds, like trying to die when I turned on the turn signals. Restoring power and MPG is just one reason to do it.

What model years were those vehicles Stubby? I'd expect a CEL on anything newer than 1996.

'95 metro, '91 miata, 2000 ranger.

Oddly, the ranger didn't throw a CEL. The older ones don't know any better.

Not sure you need to clean your grounds? check for a voltage difference between the alt case and the negative battery terminal, between either and the chassis, with the engine running. You want it as close to zero as reasonably possible.

Having a weak ground will affect the reference voltage going to your sensors. If it's bad enough, you start getting things grounding through each other, like my turn signals in the ranger, at which point weird things start happening when you turn on a load.

It will affect injectors and spark plugs on relatively newer engines.

The spark is stronger and more andvanced and the injection pulse is shorter.

So that could be a bit like chip tuning in cars that do not have later model ECU’s that can adjust to that.

Redpoint5, it's common in Honda Insights for the IMA system to function weirdly if the engine bay grounds are poor. It won't necessarily throw a CEL either; sometimes you'll just see the battery level do a "recalibration" or the IMA light come on instead. Sometimes lean burn functions poorly, with a rough or stumbling engine. I agree with you 100% that the cables themselves were not the source of the energy loss, but bad grounds can have a wide variety of symptoms which computers may not recognize.

Any sensors will be insulated from the block and have their own ground wire from the ECU. They will not be affected by the potential of the block swinging.

Better spark would be hardly measurable in FE unless he had 12% misfires.

I've seen the Big 3 get lots of recommendation in the big stereo circles, where amperage is a lot more of a thing just for keeping the sound system happy, and I think I recall seeing it get some coverage in these pages about, errrrrrr five years ago? Not sure.

I think you might be experiencing a little confirmation bias, then again I can't say yea or nay with any kind of certainty because I'm on the wrong side of the internet from your car. And all of that said, it won't hurt anything to make the upgrade. So hey, congrats on the improved performance.

:rolleyes:

I personally used 2 gauge welding cables in my car.

It’s a badly neglected system (including grounds). The upgrade means ALL ELSE on the vehicle runs well (as designed).

First time I did the B3 was on two XJs we owned.

CustomBatteryCables will the source starting point for my turbocharged diesel pickup. The B3 is possible, and a second alternator is likely (as well as yet more batteries).

The electrical SHOULD be treated as a system, not repair and wait for more problems.

80% of the time a vehicle is in the shop it is electrically related. 1959 or 2019.

Reliability IS economy.

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One of the truest things I've seen. Everything saved from a few mods can be wiped away if something gets neglected.

I just filled up today. I got 17.47 mpg. This was with weather that was a lot colder (highs around 32-35F) and with using 4WD some of the time because of snow. I think its safe to say that something I did gave me an improvement, whether it was the bigger cables or cleaning the grounds.

I just put on a partial grill block. I'm tired of my heater taking forever to warm up. So any tank averages after this would be affected by those, although I only had enough material to cover 2/7 of the grill slots.

I think that the largest source of improvement(s) was registering on Ecomodder. After being part of the forums for 6 months you are subconsciously modifying your behaviour with things like P&G, engine braking, etc.

Ecomodder has been pretty great about that. I think I discovered this forum about a year ago or so.

This is kind of off topic but the grill block worked out great! My heater is noticeably warmer! I think it did help out with mileage too. I got 17.3 mpg this tank, but the driving conditions were pretty terrible. My morning commute took an hour this morning because of snow and traffic. I'm sure using 4wd isn't that great for mpg either. So overall, pretty good!

Ya know, I was thinking about this thread and I though to myself, "Maybe I should upgrade the power wiring on my car." Then I realized neither of our vehicles have an alternator....

It still wouldn't be a bad idea if you don't have an alternator. A lot of people report their windows working a lot better and their headlights are brighter after doing the upgrade. Plus having nice, heavy duty cables are always nicer than the flimsy OE ones.

Is very hard to compare fuel spent, mainly on a several days/weeks timespan. A bit of change in winds, driver mood and self control, air umidity, air temperature and density, traffic, load in the vehicle and mainly your will to proove the concept may influence the MPG. It is prooved that changing only the way that the driver conducts the car can change results up to 30% yes, thirty percent.
I do agree that maybe your wiring could be rusty and providing a bad electrical contact overall. However improvements to electrical (ignition-sorry I don't know, is your car diesel?) can grant more fuel efficiency, in your case comparing the state of new cables against what was in the car. Maybe just cleaning up the endpoints contacts would yeld the same improvements (even if dilluted among other factors of your economy scenario).

I have no experience with those specific vehicles .

But I also was thinking that better electrical connectivity might result in the electronics being " happier " . Thus positively impacting their performance , and the vehicle operated more efficiently ? Better MPG ?

Kind of like , if the Wife is not happy , no one is happy . If the Wife is happy , every one is happy .

Wyr
God bless

I had a 4.0 ZJ that I ecomodded and hypermiled. The mods were not as effective as learning how to drive for economy.

Every little bit helps though.

The Ford yellow top injector swap is a good easy next mod if you haven't done it already. And the 99+ up 4.0 intake manifold is also a cheap and easy upgrade.

After driver training I managed to consistently average 23mpg highway in my Jeep. For a rolling brick that isn't as terrible as it could be.

I currently average around 22-23 mpg highway :)

The 99+ manifold is in the works actually. I already have it; I'm just waiting to be able to afford a Banks header and exhaust wrap before I install it

There's a couple of things I have noticed since having a scangauge. My gas mileage is really terrible when my engine is cold. I really want a block warmer but I live in an apartment right now. I also get terrible mileage while accelerating, so I think that mods like the newer manifold will help a lot.

These are both also true of my Insight. Mods which help it to warm up faster or feed it warmer air help, but don't fully offset these.

A cold engine is unavoidable. Given stock equipment, there is always a penalty which is right at 45-miles at 45-mph or better. All fluids and grease must come to their specified operating temperature BEFORE heat burns off condensation and acids formed. It takes close to 90-minutes on a 70F day before tire temperatures stabilize. Thats where warm-up ends.

A short trip is ANYTHING less than this.

FE is, in one sense, cutting cold starts to a dead minimum.

Coolant temp is only one step. Oil temp is more important for “reading” the warm-up process.

I had several XJs. Great motor architecture in the 4.0L. Literally the reason Chrysler bought Jeep.

Temp control is not the vehicles strong suit. Asking a straight-six to work under a load means airflow. Once all that mass heats up, it isn’t shed easily.

Be glad it’s EFI. That’s 90% of the battle.

Straight axle vehicles are plagued by bad steering & handling. Can’t push it like a rice-burner. So, don’t. New HD shocks & tight front end are important.

Tires & brakes should last 70k given best quality parts.

Tires themselves are where savings occur: closed shoulder highway rib

.

I've thought a lot about fluid temperature management actually, though I'm really limited by not having a garage right now. Apart from a block heater I would like to try one of those magnetic oil pan heaters. A transmission cooler would work nicely too I think.

I have new shocks I need to install. Unibody stiffeners are in this Jeep's future too. I've heard that those really improve handling.

An idea that I've been toying with is getting a tune for fuel economy. I will have to get my Jeep tuned anyway after I rebuild the engine. I think lowering shift points in my automatic would be good. If it is possible I would also like to lower fuel consumption at idle by like 10% or 15%.