i wanted to write this in a separate thread as this will be probably googled much.

i was overseas for two months, and as expected found the battery dead flat when i got back.
jump started and charged for 30-40 mins, didnt drive two days and it was again gone..
having noticed the battery is about 3 years old, i said replace it anyways..
well so.. done here are the good parts i noticed

1- car has about 10-15% more power
2- aircon works better
3- auto transmission shifts faster and smoother

but the bad part is..
my fuel consumption increased drastically

average combined was 9.5 - 10.5 now its 11-12
cruising on motorway at 100-110kmh was 5.6-6.5 now its 7.5

one possibility might be that i drove a bit too aggressive after battery replacement and the chip adjusted itself for performance... but how would that effect the motorway stable increment?

its not about the fuel, as tank was half when i had the replacement and noticed the increase almost immediately.
filled another tank after, observed again, km per tank dropped to 480km (worst ever) down from 580-600 average
im on the second tank now, half way down and only did 200 kms on motorway.. seems awful

any suggestions ideas?

cheers

I dont think any of what you stated is anything to do with a new battery. I think its all coincidental.

I had a new battery installed a few weeks ago, and bam driving out of the auto electrics driveway the car felt like it had more power down low, and the power delivery felt much stronger.

Like yourself a week later i noticed my fuel consumption was just under 10.0L per 100 now its in the mid 13's.... Im using the same fuel (shell 95) drive the same route each day to work...

I noticed when I put a new battery in last week in my TJ, I just managed to see off a Ba turbo ute that had had the run on me all month. Thanks to the battery, now feels like a TMR!!

I'm going to put a new and bigger battery in my TJ. If what you guys say is right, an easy extra 50 Kw. lol

Braille Batteries make a battery out of Carbon Fibre that ways only 1.7kg, perfect for your experiment Max lol.

Braille Batteries make a battery out of Carbon Fibre that ways only 1.7kg, perfect for your experiment Max lol.

Perfect! Nothing perks a car up more than fresh electrons!

I'm going to put a new and bigger battery in my TJ. If what you guys say is right, an easy extra 50 Kw. lol

i dont think this is a power increase to an already healthy system, but it does make somewhat sense to me that wiring' plugs and sockets in a 10+ year old car would not be at its best in terms of conductivity and current delivery.
combined with a poor battery IMO this could cause an overall reduction in power in demanding situations like accelerating fast with aircon on etc etc..
so probably what we're observing is a bit support from a fresh battery restoring what was already lost.

i have a lot of car audio parts and wirings, and i often see oxidized power cables, these days it makes me think, seeing the puny power cable from alternator.. god know whats it like inside :P

considering the big 3 upgrade just to see if it does anything to performance.

It sounds like the ECU and auto were previously 'out of whack'. A result of installing a new battery is that you disconnect the old one first, which resets everything. However, the ECU and auto shouldn't be 'out of whack' in the first place!

So I read the title as you swapped around the terminals and was ready to see the aftermath of this, how wrong i was lol.

I've always found a car to run smoother after a battery replacement of a dieing battery, starts easier, idles smoother etc. Not sure if that's because of the "reset" or because spark is now better.

Just a thought...a nice new battery is completely charged at the factory.
Therefore, your alternator is not doing as much work, therefore car feels like it has more HP...

Is that too oversimplified to be the correct answer???

My mum's fuel consumption in her TJ actually went down when I replaced her battery? She didnt say anything about any power increase tho...

"Just a thought...a nice new battery is completely charged at the factory.
Therefore, your alternator is not doing as much work, therefore car feels like it has more HP..."

No - even if your alternator was putting out maximum current (130 amps @ 14 V = 1820 watts) with an engine capable of putting out over 140 kW. You wouldn't even notice if it was working at all. The answer is that you probably had about 13 volts or even less, now you have over 14 volts. Much more powerful spark, better performance. Also there is the placebo factor where you think it is better...

there is the placebo factor where you think it is better...

+1

"I just spent $$ on my car, it had better appreciate it. Does it run better? Goodness, so it does!" lol

no folks.. no placebo here

i reset my counter every time i fill up the tank, and fill up again only when fuel light is lit up, and observe both the digital average meter as well,
been doing this for 1.5 years now at each and every time.

car was just sitting while i was away, and it has always been serviced with best parts

under 500kms per tank readings in a row twice isnt placebo to me..
as it is with the power.. i mostly even turn off my good stereo in the car to focus on the engine and acceleration and occasionally make aggressive take offs or sprints,
i am 100% sure on all aspects i mentioned.
more power yes
smoother and faster tranny yes
more fuel gone yes
aircon is better yes

maybe i gained back what was already lost due to weak battery.. i dont know. but car already had decent power before this.. apart from a "very slight" stall when accelerating between gears
now when i kick the pedal down, car literally jumps forward at gear changes say 1 to 2 and 2 to 3

i have NGK laser iridium spark plugs on "both" banks (maybe these guys benefit from better current?)
NGK blue leads newly installed

i will reset the ecu again if i can be bothered, and drive granny style for 10-15 kms see what happens.

What are you using to determine these power increases? When did you last have your butt-dyno calibrated?

What car did you drive while overseas? After 2 months without driving a car of course its going to feel different, I got back in my 4cyl magna after driving a landcruiser for 2 weeks and thought I'd lost about 50kw.

What are you using to determine these power increases? When did you last have your butt-dyno calibrated?

What car did you drive while overseas? After 2 months without driving a car of course its going to feel different, I got back in my 4cyl magna after driving a landcruiser for 2 weeks and thought I'd lost about 50kw.

butt-dyno :)
i didnt drive much overseas maybe once or twice, but generally brother in law drove me around in his little peugeot.
after i jump started the car, i drove for a bit and did appreciate and was happy to be back on the good v6. after new battery change was significant im positive about the power increase
she definitely burns more fuel, no smoke, no raw fuel coming out of exhaust, so obviously this is turned into power..

i had a mate of mine drive the car yesterday, he had a 3lt manual that he sold a couple weeks ago.
he thinks my 3.5 auto unusually responsive for its kind, as manuals magna's have more power on the wheels and auto trannys are slow

this is probably due to change of ecu settings and healthy electrical system.. still due testing

I have heard that having a good battery in an ECU controlled car can increase the responsiveness of the computer, at least yours isn't like the 8th gen VR4s where the ECU can forget how to 'Car' after the battery gets disconnected and will stall (even autos) whenever you stop for about 200kms of driving.

i have no idea.. i am sure there are magna guru's around to confirm that

I've found my Magnas feel a lot more powerful after driving my wife's Lancer.
Figured out that it is in the right foot, Lancer needs a big prod to get moving nicely, when I get back into the Magna my right foot does the same and it takes a while to recalibrate my foot to adjust to the Magna's superior torque and power at low revs.

So it probably isn't placebo, just the right foot "remembering" how it acted in the last car you drove.