Member Since: 06 Mar 2006
Location: Lancashire
Posts: 259
Fuel/Elec. Load/17" wheels (was interest to TDV6'ers)
Just to clear something up: Having lights/stereo,etc switched on does NOT affect fuel economy! The alternator is connected to the engine at all times, not JUST when you're using electrical power. Does the engine pitch rise when you turn on the lights? NO!2005 Disco 3 TDV6 7 seater. Leather, DVD, fully colour-coded.
1970 Triumph Spitfire Mk3
1981 Triumph TR7 FHC (16V Sprint)
2001 Porsche Boxster 2.7
MTD 12.5 hp Ride-on mower!!!
5th Jun 2006 6:46 pm
Ken
Member Since: 20 Feb 2006
Location: Here
Posts: 10865
No it Dips (Increased load on engine)
5th Jun 2006 6:54 pm
bkehoe
Member Since: 24 Feb 2006
Location: Wexford
Posts: 1481
Any electrical load does result in lower fuel economy. It becomes harder for the engine to rotate the alternator as more and more current is being drawn.IE - 05 D3 TDV6 HSE - Zambezi Silver
SA - 07 VW Golf TDI - White - Sold!
5th Jun 2006 7:05 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
der... schoolboy error there Mr. Bling - conservation of energy and all that
5th Jun 2006 8:08 pm
Mr Bling
Member Since: 06 Mar 2006
Location: Lancashire
Posts: 259
But the friction produced by the alternator remains constant regardless of the load being drawn, and it is only this friction which affects fuel economy!
I stand my ground on this. There is no increase in friction just because more current is being drawn...2005 Disco 3 TDV6 7 seater. Leather, DVD, fully colour-coded.
1970 Triumph Spitfire Mk3
1981 Triumph TR7 FHC (16V Sprint)
2001 Porsche Boxster 2.7
MTD 12.5 hp Ride-on mower!!!
5th Jun 2006 8:23 pm
Ken
Member Since: 20 Feb 2006
Location: Here
Posts: 10865
Its nowt to do with friction Its increased load on the engine. Thus it works harder (engine) thus lower mpg.TFC will cover the oily bits I'm sure
Last edited by Ken on 5th Jun 2006 8:59 pm. Edited 1 time in total
5th Jun 2006 8:27 pm
DG Site Moderator
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50979
Let Dr.DG explain......by the magic of pictogram
Air conditioning, power steering, windshield wipers, and other accessories use 2.2 % of fuel passing through the engine. Fuel economy improvements of up to 1% may be achievable with more efficient alternator systems and power steering pumps21 year LR veteran > D2 GS 2003 > D3 S 2006 > D3 HSE 2009 > D4 HSE 2013 > D4 HSE 2015 > D5 HSE 2018 > DS HSE R-Dynamic P300e 2021
5th Jun 2006 8:39 pm
SimonH
Member Since: 29 Apr 2006
Location: North Yorkshire
Posts: 161
Have to go with Mr Bling on this one. Greater draw of electricity does not make it harder for the alternator to go around. It does put more drain on the battery, not the engine.
Have we all been getting 2mpg less when we drive at night?? I havent noticed this in the past 23 years of driving.NOW SOLD: 2006 TDV6 SE Auto Zermatt silver with Alpaca Leather
Tow Pack, PTI, Full Size Spare
5th Jun 2006 8:45 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
nope, sorry, more electrical load = less mpg remember Heisenberg's theorem?
don't make me give you the full physics lesson
5th Jun 2006 8:49 pm
simon
Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
10forcash wrote:
nope, sorry, more electrical load = less mpg remember Heisenberg's theorem?
don't make me give you the full physics lesson
Iain my boy... tut tut, you never listened at school and you have obviously forgotten my correction last time you brought Heisenberg up.
I therefore correct you again my boy :
Heisenberg discovered (and proved without doubt) the compensation factor during involuntary tests he did that included accelerating down a huge white vortex tunnel following one very large Brownian motion.
Not eating the local lamb curry was indeed the best way to compensate against future incidents.
So in essence, the very fact of putting your lights on will make all difference to your MPG. Unless that is, your name is Slimer. He has enough lights to frighten all the rabbits in Woking.
5th Jun 2006 9:20 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
OK, you asked for it
Conservation of energy states that the total amount of energy (including potential energy) in a closed system remains constant. In other words, energy can be converted from one form to another, but it cannot be created or destroyed.
With the discovery of special relativity by Albert Einstein, it was found that energy is one component of an energy-momentum 4-vector. Each of the four components (one of energy and three of momentum) of this vector is separately conserved, as well as the vector length (Minkowski norm). The latter is associated with invariant mass and rest mass. The relativistic energy of a single massive particle contains a term related to its rest mass in addition to its kinetic energy of motion. In the limit of zero kinetic energy (or equivalently in the rest frame of the massive particle, or the center-of-momentum frame for objects or systems), the total energy of particle or object (including internal kinetic energy in systems) is related to its rest mass via the famous equation E = mc2. Thus, the rule of conservation of energy was shown to be a special case of a more general rule, alternatively called the conservation of mass and energy, the conservation of mass-energy, the conservation of energy-momentum, the conservation of invariant mass or now usually just referred to as conservation of energy.
The conservation of energy is a common feature in many physical theories. It is understood as a consequence of Noether's theorem which states that any theory whose description is not sensitive to a starting time will have constant energy. In other words, if the theory is invariant under the continuous symmetry of time translation its energy is conserved. Conversely, theories which are not invariant under shifts in time (for example, systems with time dependent potential energy) do not exhibit conservation of energy.
In quantum mechanics energy is defined as a time derivative of wave function. Lack of commuting of time derivative operator with time mathematically results in uncertainty principle for energy definition: the longer the period of time the more precisely energy can be defined (energy and time become conjugate Fourier pair).
How does this relate to a Disco 3? (or any other vehicle)
Well, an engine as a source of energy is a closed system, traditionally measured in BHP, but can also expressed in kW. A charge alternator has a finite output, let’s say 150Amps at 14.5 volts, Power equals volts times amps so 150 x 14.5 = 2175W – the maximum finite output from the alternator. If the Discovery 3 has a maximum engine power of 140kW, then 2175W (2.175kW) is 1.5535714285714285714285714285714% of engine power, hence is also 1.5535714285714285714285714285714% of engine load – excluding friction.
Of course, maximum output is neither desired or possible, in cases where it is not desired, the regulator will reduce demand upon the energy source (engine), thereby reducing the energy transfer from the engine and the subsequent fuel consumption. In cases where demand cannot be met by the alternator, by virtue of low output, which is speed dependent – energy demands are supplemented by the stored energy in the vehicle battery, which is then recharged at an approximate rate of 1.3Amps input for every 1 amp discharged.
Following the Conservation of energy theorem, this energy can only come from the vehicle’s engine – which of course gets it’s energy from the burning of fuel… see the link now?
Of course, you may well get a higher energy consumption due to the number of flies hitting your windscreen – but that’s another debate altogether
5th Jun 2006 9:32 pm
Big Al
Member Since: 20 Jan 2005
Location: Wiltshire UK
Posts: 143
Guys,
What do you think a dynometer is then, this is the part that provides resistance on a rolling road, therefore any generation of an electrical load from the altenator will lead to losses. Magnifiy this through the drive train, which although is extreamely efficient still will lead to minor losses. We are generally taking minor losses but they may just add up to 1% when you consider the airconditioing equipment etc.... lights alone and the radio though won't cause any significant impact as they draw stright off the battery.
5th Jun 2006 9:34 pm
simon
Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
BUT !
What did he know anyway ??? Worlds moved on since all that text was put on a web site somewhere.
Still think if your tank is nearing 1/4 full and you 'forget' to fill up or notice that you need to fill up... its your own fault really and not that you didn't read the theorem.
5th Jun 2006 9:37 pm
simon
Member Since: 11 Jan 2005
Location: Shropshire
Posts: 18296
Big Al wrote:
Guys,
What do you think a dynometer is then, this is the part that provides resistance on a rolling road, therefore any generation of an electrical load from the altenator will lead to losses. Magnifiy this through the drive train, which although is extreamely efficient still will lead to minor losses. We are generally taking minor losses but they may just add up to 1% when you consider the airconditioing equipment etc.... lights alone and the radio though won't cause any significant impact as they draw stright off the battery.
Al !! Thank god your still around to save the day
5th Jun 2006 9:38 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
errrrr. yep - can't blame the rest of the world 'cos you forgot to fill up
AND
This is the first time 'all that text' was put on a website...
AND
as stated above, the electrickery doesn't come from the battery, but the alternator - the battery is there mainly for starting and to supplement the alternator when times are hard bit like an overdraft really
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all difference to your MPG. Unless that is, your name is Slimer. He has enough lights to frighten all the rabbits in Woking.
