hot earth

Electrical wholesaler

 

i know its a stupid question... what's a hot earth system?

answer to your question... you can source good quality cable through companys like:
- Radio Parts
- Arlec
- HPM, etc

Something you might like to take into consideration though. When buying cables, SOOO many people get 0 guage and other massively thick wire, when they don't require it...

do your homework in finding out what the maximum current you will encounter for this cable and buy one that suits it. if you want to use the jumper leads you have, the reason they are "multistranded" so finely is purely for flexibilty.

Cables which are solid core, will carry just as much current as the same "effective gauge" multistrand core. (ie: its purely for fleixibility)

 

What's a hot earth system? Had to look it up on google myself! Looking at it briefly.......seems like snake oil to me!

Basically its connecting all the vehicle electrics, injector and coil grounds directly to the -ve of the battery, bypassing the main earth connector of the engine block, having possibly five different wires going to the -ve of the battery.

Reason, claims of less voltage loss lower resistance etc.

Cant see it myself! The manufacturers supply a juicy lead going from the engine block to the -ve of the battery(needed for cranking the starter). All the components are grounded to the engine block as they are. Unless the grounding of these components was extremely dodgy cant see how any measurable voltage differences could be achieved.

Whether these differences would create more power, doubt it, the manufacturers could easily counteract if it were a problem by increasing the supply voltage slightly(regulator output).

The sight I visited boasted testimonials etc, so obviously at least some think it works........but Ill need something more concrete.

 

saw i write up on hot earth systems in SC mag a while back, had a car on the dyno before and after hot earth and it ran more rwkw with the hot earth

 

I made my own hot earth set up using some 8 gauge stereo amp wire i had lying around
a $2 pack of yellow ring terminals which i just opened up a bit to fit on wire works fine
made my headlights brighter not sure if any power was gained

 

More RWKW with a hot earth??

Sounds like absolute BOLLOCKS to me!!! I can think of absolutely NO scientific basis for such a claim - can anyone enlighten me???? Maybe the air was cooler (more dense) after they screwed around for hours doing the hot earth - that might have given them a couple of KWs....

Vnrockit - I can see how grounding your headlights direct to the battery might get your headlights a little brighter (thin-ish standard ground wires combined with a not-so-great connection to the chassis) - but more power from the donk?? Smells very much of bull**** to me....

 

I dont support it. As guys above have suggested, as long as your factory wiring is in good nick there is no need for it. If you are having a problem, fix it.

Multiple earths can cause earth loops, so yes, you can cause problems by doing it.

If your not happy with your money and really want to spend it on your car, upgrade the existing wiring to some thicker stuff - but unless there was a problem to begin with your not going to have any improvment.

 

I seen somthing ages ago about this and im trying to think back and im sure it was all to do with earth loops and eddy currents i think. Given that a commodore does not have any sensitive electronics, i would be sceptical that there would ever be a single kw gained. Brighter headlights...maybe. Easier starting....maybe too, but hp gained in the commo by this definatly not. The only reason for brighter lights and better starting would be all to do with bad earthing from the start and by running it direct to the batt- simply takes a few joins out of line, plus steel is not a great conductor compared to copper, thats why anyone with a battery in the back will always run a + & - wire to the starter motor instead of earthing out to the chasis.

 

Possibly one of the most incorrect theories and greatest waster of time and money and problems in the auto electric caper. Whilst copper is a better conductor than steel, a half inch cable of copper just doesnt compare to a couple of hundred kg of steel(the body of the car) for use as a conductor. There will be considerable voltage drop when starting the car through an extra 2-3m of cable, the voltage drop through the body(using well chosen earths at the rear and front) is near unmeasurable.

 

commsirac, Ive wondered about this before but havent been able to find an article discussing it in a bit more detail. Did you know of any sites that I can read a bit more about it?

I have found this site interesting:

Copper and electricity. Resistance and resisitivty.

It works out that copper is about 6 to 60 times (depending on the steel) a better conductor:




Using the formula:

resistance = resistivity × length / area

If you assume a length of copper and the length of the steel chassis to be the same, you get:

resistance = resistivity / area

Lets say the copper is 10x better than the steel. Im not sure about the cross-sectional area though.

If you used 1 gauge wire, it has a CSA of 46mm^2

I dont know a CSA for a chassis though???

Lets say it was 4mm thick steel. 1/2m high. Thats a CSA of about 2000mm^2. Or about 43 times bigger.


My rough maths tells me that

resistance of the steel = 10 / 43 = 0.2 or 1/5th of the resistance of the copper. So it does look like the steel is better.


BUT

If you assume that the steel has a lower conductivity, and instead of being 10x worse, its 43x worse (to make the maths easy):

43/43 = 1

Both are exactly the same.

If you went a bit further and said that the steel is a full 60x worse than the copper, the copper would work out better.

60/43 = 1.4 (The resistance of the steel is 1.4 times the copper).

Thats rough, but I reakon that the resistance of the cars chassis may not be a heap better, but probably about the same as a piece of copper wire. Maybe my CSA of the chassis in my maths above is out, but:

Copper is 6-60 times a better conductor than steel
The steel has a bigger CSA by about the same amount, so the two really cancel each other. Thats what I can work out anyway, unless I can read somewhere that can make it a bit clearer for me.

 

I think estimating the total amount of metal between the starter of the car and whereever in the rear the batt sits to a sheet of metal 4mm by 2m? by 0.5m is a bit understated! That would be about only 32kg!

At least multiple that number by 10.
My reckoning would also be the rest of the metal in the car(north and south of the starter and battery) would also act as parallel carrying conductors and also reduce the resistance more.

I have actually tried this out on real holdens, I could only just measure a voltage difference between the rear and front earth connections(chassis rails) when cranking the starter motor on a 6cyl holden. (cant remember but in the order of hundreths of a volt)

However, as has been alluded to by Immortality, it is the quality of the earth connection that can have the biggest effect. Just how well the cable is crimped/soldered connected to the terminal used for the earth can create a large voltage drop. so in some ways reducing the number of earth connections between the starter and the battery is desirable.

I dont subscribe to the theory that the modern car is only held together with a couple of spot welds that could glow red hot if the starter current passes through the body.

 

Seems even in the modern car that the body/chassis still provides good enough electrical return....good enough for the Holden engineers anyway.

The VE commodore's rear mounted battery is earthed at the rear, and a body to engine earth under the bonnet.

 

upgrading your earth's can very often make a difference.

as to why? I'm not going to waste my time explaining it to a bunch of commodore drivers

however, your best bet is just to upgrade the battery to chassis, and chassis to engine cables.

most cars will only have like 8ga cables for these, upgrade them to 4ga or bigger.

 

Why not give it a go, Ill tell everyone if you are talking nonsense or not!

 

Also interested. You should have no problem explaining if you have good reasons.

 

you've already said its pointless, so you've already proven that you dont know what you're talking about