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Author Topic: Why Does Putting A New car battery Dramatically Enhance The Cars Performance ?  (Read 68161 times)

Offline neilep

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Dearest Battery-ologists !


As a sheepy I of course just luff batteries. Batteries are my all time favourite thing ever that is portable and has magic power inside them. As ewe know they also grow on trees..like lemons !..This is true !






A Bona Fide Piccy Of Me Next To A Battery Tree !..so There !!

So, this is what I want to know...I recently picked myself a fresh new battery  from the Halford Orchard and put it in my car all by myself !.....The man from Halfords offered to do it for me but I declined because he wanted £10 ...sheesh !!

Anyway, when i put the new battery in...the change of performance in the car was extraordinary !!...it runs smoother and faster !...I did not expect such a contrast....all I thunk I was doing was replacing the battery !.....

Why's that then ? Why  Did Changing The Battery Increase and Enhance My Cars Performance ?



As a firm believer of empirical study I snuk into my neighbours house at 3am this morning....he  has a hearing aid which I am sure requires new power...he gladly  co-operated being sedated because there was no protestation after the struggling and passing out....I removed his hearing aid and plugged it into the national grid......Whilst he slept like a baby he did not object to my going through his wallet and visiting my 24 hour local TESCOS * where he allowed me to reach his credit limit buying a lot of electrical goods and groceries for myself !....anyway...upon returning to his abode he came to and with the aid of the brass band and death growls performed by the Slipknot tribute orchestra I turned his hearing aid up to maximum........Well.....how rude !!...after only three hours of musical luff he just went all limp and fell asleep !...lol..someone said he had actually passed out  and attempted to prove it by slapping him and prodding his toes with needles !..but I happen to know he's a member of the amateur dramatics and therefore he can act !..I am sure he was just ignoring me !!..so..no luck there  !!

Can ewe help ?

Thanks

hugs and shmishes


Neil
Are Ewe Ever-Ready To Offer Dura-Help ?
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Oh battery, thou art so fine in form and splendour in nature
Like a bee in flight ewe are renewed in your vigour
Energetic in motion ewe offer power humming
In wifeys presence ewe also do buzzing !



lol

*Other well know supermarket traders are also available through out the night !!
« Last Edit: 07/02/2011 21:52:07 by neilep »


 

Offline Geezer

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Er, well, assuming your jam has one of them infernal combustion engines in it, I don't think changing the battery should make any difference to the way it runs. I think what we might have here is a bit of coinkydink. It's possible that while you were rummaging about trying to find where to put the new battery, removing unwanted pieces of pedestrians, bicycles and the like from the engine compartment, you may have temporarily improved a dodgy electrical connection by jiggling it.

However, you might also consider submitting your question to these geezers -

http://www.cartalk.com/content/showpodcast/index.html
 

Offline neilep

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Er, well, assuming your jam has one of them infernal combustion engines in it, I don't think changing the battery should make any difference to the way it runs. I think what we might have here is a bit of coinkydink. It's possible that while you were rummaging about trying to find where to put the new battery, removing unwanted pieces of pedestrians, bicycles and the like from the engine compartment, you may have temporarily improved a dodgy electrical connection by jiggling it.

However, you might also consider submitting your question to these geezers -

http://www.cartalk.com/content/showpodcast/index.html


Thanks ewe Geezer me old chummy McMate !

I thought this too that changing the battery should not really affect the cars' performance....but it was mentioned to me twice by two different passengers..and so.... I had to believe that it was not a placebo effect kind of thing !. I'll hang the question out to dry hear for a while and then offer it to the fine chums at the other end of that link ewe supplied if no categorical answer comes along !


I did wonder if the new battery may have had an effect on the engine management system ?..I just do not know !
 

Offline Geezer

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I did wonder if the new battery may have had an effect on the engine management system ?..I just do not know !

(Thinks - that's a good point.)

Ah! You could be right.

When you disconnected the old battery, the engine management system "forgot" everything. When you installed the new battery, the EMS reverted to it's default settings. It will now be learning new settings and will probably get back to the same settings that it had before you disconnected the battery.

The default settings are not optimized for fuel economy, so the fuel/air mixture is probably a bit "rich" at the moment, which would explain improved performance. However, your MPG is probably not as good as it was before.
 

Offline RD

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If the battery is poor it will draw more current from the alternator than a new fresh battery.
The increased current increases the force required to rotate alternator shaft: stronger current => stronger magnetic fields in the alternator, (cf magnetic brake). The increased force required to rotate the alternator will increase the load on the engine (a little), which will then reduce car performance (a little): poorer acceleration, increased fuel consumption.
« Last Edit: 08/02/2011 08:17:57 by RD »
 

Offline neilep

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I did wonder if the new battery may have had an effect on the engine management system ?..I just do not know !

(Thinks - that's a good point.)

Ah! You could be right.

When you disconnected the old battery, the engine management system "forgot" everything. When you installed the new battery, the EMS reverted to it's default settings. It will now be learning new settings and will probably get back to the same settings that it had before you disconnected the battery.

The default settings are not optimized for fuel economy, so the fuel/air mixture is probably a bit "rich" at the moment, which would explain improved performance. However, your MPG is probably not as good as it was before.

Gosh !...thanks Geezer .......ewe have explained it far better than I ever could. I did wonder about the EMS. So, I guess that means when ever I need a boost in car performance I just need diconnect and reconnect my battery !....but...at a cost to fuel economy !.....shesh !!...theres always a darn negative !!
 

Offline neilep

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If the battery is poor it will draw more current from the alternator than a new fresh battery.
The increased current increases the force required to rotate alternator shaft: stronger current => stronger magnetic fields in the alternator, (cf magnetic brake). The increased force required to rotate the alternator will increase the load on the engine (a little), which will then reduce car performance (a little): poorer acceleration, increased fuel consumption.

Thank ewe RD. This must be right also...although I had no indication on the panel that the battery was failing there were days (Cold days) that the car just did not start and I had to us wifeys car to start mine !...I guess my battery was on the way out !....
 

Offline Geezer

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I doubt that you would notice the effect of the alternator load on the performance. The maximum power it could take from the engine is probably under one horsepower.

Yes, you could boost your performance by periodically disconnecting the battery, although it may be necessary to leave it disconnected for a few minutes to reset the control system. BTW when you disconnect the battery, always remove the "earthy" side first and reconnect it last. These days this will almost certainly be the negative side.

The reason for this is because it's a lot safer, although it's a little counterintuitive. If you accidentally connect the negative terminal to the vehicle bodywork with your spanner, nothing will happen. If you start with the positive terminal and you accidentally connect it with the vehicle bodywork with your spanner, very bad things will happen.

Once you have disconnected the negative terminal, even if you short the positive terminal to body, there is nowhere for the current to go, so nothing bad happens.
 

Offline RD

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I doubt that you would notice the effect of the alternator load on the performance. The maximum power it could take from the engine is probably under one horsepower.

OK what about a low battery only producing a poor spark leading to incomplete combustion and consequently poor performance ? ...

 

Offline neilep

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IBTW when you disconnect the battery, always remove the "earthy" side first and reconnect it last. These days this will almost certainly be the negative side.



ewe just answered my next kweschun !..I was gonna ask why when i asked which way to disconnect and reconnect my battery did the guy say Nosy People Pick Noses !...ie Negative Positive to disconnect then Positive Negative to reconnect !
 

Offline Geezer

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I was about to post this  :D

OK what about a low battery only producing a poor spark leading to incomplete combustion and consequently poor performance ? ...


That could happen if one or more of the cells in the battery was shorted out. Then everything would be running off about 10, or even 8 volts. But modern cars have very effective solid state high voltage generators - usually one for each cylinder. They don't have mechanical distributor points, or even a distributor. I'm pretty sure these modern systems produce excellent sparks, even when running off a considerably reduced input voltage. That's one of the reasons modern cars start so easily.

The other thing is that it's unusual for batteries to fail that way. When the cells fail, they are more likely to develop a high internal resistance due to sulphation of the lead plates, so the battery can't take current from the alternator to charge it. This means the load on the alternator will actually be reduced.

As long as the alternator is working properly, the electrical supply to the car will be fine. It just won't start well because the battery can't turn the engine over fast enough.

 
 

Offline RD

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It since occurred to me that a weaker spark could also alter timing (a little).

There will be an interval between the spark and the explosive force in the cylinder reaching its peak, (i.e. the two are not simultaneous).

If the spark is weak this tiny interval will increase and alter the timing which could reduce car performance.

[Analogy: if you lit two identical piles of wood, one using one match and the other using two matches, the two-match bonfire will reach its maximum sooner than the one-match bonfire].
« Last Edit: 09/02/2011 06:54:39 by RD »
 

Offline Pumblechook

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Surely once the engine has kicked off the alternator provides the spark and current is flowing into the battery and not out of it.

NOW...put a strong magnet on the negative lead to the battery and your mpg will go up!
 

Offline neilep

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Surely once the engine has kicked off the alternator provides the spark and current is flowing into the battery and not out of it.

NOW...put a strong magnet on the negative lead to the battery and your mpg will go up!

Really ?...will putting a magnet on the negative really affect the mpg ?
 

Offline peppercorn

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Really ?...will putting a magnet on the negative really affect the mpg ?

Oh dear Neil! You are a sucker for those snake-oil salesmen, ain't ya? :D
 

Offline neilep

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Really ?...will putting a magnet on the negative really affect the mpg ?

Oh dear Neil! You are a sucker for those snake-oil salesmen, ain't ya? :D

I know !!...I'm a naive sheepy !!....someone even sold me a woolly cardigan !
 

Offline SeanB

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Loose connections on the old battery, or a weak cell, can cause spikes and fluctuations on the electrics of the vehicle. If you have an old points and coil system this will give rise to an erratic spark that may lead to a misfire or a late firing on random occasions, probably too brief to notice for most, but they will lead to poor running and poor fuel economy.

With an electronic ignition the same can occur, as the computer works out the energy in the spark from the battery voltage, and a drop will result in a weak spark, as the voltage is sensed every few seconds rather than per spark, as the battery is assumed to be good at keeping a constant voltage. As well low voltages can cause the unit to be unable to do proper operations like control idle and mixture properly, as the actuators and such do not operate below a certain voltage, leading again to poor running.
 

Offline Geezer

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Er, I think some of us might be overlooking something. When the car is starting and the battery is turning the engine over, the voltage appearing at the electronic ignition system can be considerably lower than 12 volts, particularly on a cold day when the engine oil is more viscous. This voltage "sag" is a function of the internal resistance of the battery, the current drawn by the starter motor, and any voltage drops in the supply and return wiring and connections.

Because of this, the ignition system still has to operate over a wide range of input voltages. If it didn't, the car would not even start. Once the car starts and the starter is no longer drawing current, the voltage will be determined by the alternator more than anything else. At that point, the battery is pretty much out of the picture.
 

Offline Pumblechook

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You could take the battery out once the car has started.
 

Offline peppercorn

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This voltage "sag" is a function of the internal resistance of the battery, the current drawn by the starter motor, and any voltage drops in the supply and return wiring and connections.

For this reason my old car - a Vauxhall Viva - had a ballast resistor in series with the coil when running/cut-out of the circuit when starting.  I could see the sense in the idea, but the best thing I ever did was rip that blasted resistor out!   All the cold starting problems went away when I did.
 

Offline Geezer

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This voltage "sag" is a function of the internal resistance of the battery, the current drawn by the starter motor, and any voltage drops in the supply and return wiring and connections.

For this reason my old car - a Vauxhall Viva - had a ballast resistor in series with the coil when running/cut-out of the circuit when starting.  I could see the sense in the idea, but the best thing I ever did was rip that blasted resistor out!   All the cold starting problems went away when I did.

I think the ballast resistor was also intended to prevent you from frying the primary of the ignition coil in the event that you left the ignition turned on while the engine was not running. It was a bit like Russian Roulette though. That would only happen if the points happened to be closed - probably something like a 50/50 chance.
 

Offline peppercorn

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I think the ballast resistor was also intended to prevent you from frying the primary of the ignition coil in the event that you left the ignition turned on while the engine was not running. It was a bit like Russian Roulette though. That would only happen if the points happened to be closed - probably something like a 50/50 chance.
Yes. For that reason I never sat with the ignition on if the engine was off.

You could take the battery out once the car has started.
What you want for that is a nice Magneto!


Does Sheepy want to do an experiment for us & disconnect the battery from the ECU before each trip, to see if the fuel economy is lower than when the ECU has 'learnt' - ?
 

Offline SeanB

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While I have seen a shadetree mechanic jump start a car using the loaner battery idea ( Eh borrow de battery fro mi odder cah and then remov it and plis mi batteri bak agin) it would not be a good idea, as the battery is needed when the engine is running, providing a current sink for the alternator so it can regulate, as well as providing a smooth voltage for the ECU. If the battery has poor connections the alternator can easily supply over 60V to the rest of the system before the regulator switches off, as the battery normally is the load. Not good for the alternator, or anything electronic or of low thermal mass like indication lights and such.
 

Offline Geezer

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Sean, I think alternators regulate their output voltage, so it should be OK to disconnect the battery while the engine is running, although I certainly would not encourage anyone to try it  :D
 

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