Replaced My Car Battery Today... And Wow...

[N35QU!K]

I replaced my old car battery with a fresh, brand new one, and to my complete surprise, I experienced a very noticeable increase in throttle response in comparison to when I had the old battery. My old battery was beginning to show its age over the past three months, and it finally gave out today; luckily I was planning on getting a new battery anyways, as lately, I've experienced sluggish engine startups, slow power windows, as well as dimming headlights and skipping music while braking.

To be honest, I didn't expect anything special to happen, but I can personally say that the car feels a hell of a lot better now. No more slow power-windows, etc, and surprise surprise, the car performs just a little bit better Looks like I was more overdue for a battery change than I thought :P

[mvftw]

I may Not be the new battery, but you also reset the computer...

[bigbird]

ya know, you may be having problems with your alternator. if an alternator is not runnin good then the car will draw more power from the battery and thus ware it out faster. every replace yours?

[Jeeves]

Originally Posted by bigbird

ya know, you may be having problems with your alternator. if an alternator is not runnin good then the car will draw more power from the battery and thus ware it out faster. every replace yours?

Exactly.

The battery is really not quite as important as everyone believes it to be. The battery (in essence) has two main duties:

1) Starting
2) Acting as a large capacitor when momentary/instaneous high demands are put on the system.

Other than that the electrical system is regenerative by means of the alternator. When a high (constant, not instaneous) demand comes in, the battery is first to respond, then the alternator steps up its output to the system (and the battery, so anything lost is recovered). When the power is required without 'waiting' on the alternator, the battery is relied on to have the amps on hand to do the task necessary.

While the car is running, you can remove the positive lines from either the alternator or the battery and the car will keep running. Now, if you pull the line off the battery and the car dies immediately, it means your alternator is dead. Vice-Versa is also true.

So, where you'll see a difference is if the Alternator is pushing out more current (amps) to the system. Things like windows, fans, inverters, and some other devices are continuous high load devices (meaning they'll rely more on the alternator kicking out power than the battery) while other things such as Amplifiers are instantaneous devices, meaning that the battery has to have the amps on hand to drive it, it can't wait on the alternator to respond. Starting relies on the battery simply because the alternator's not runnign yet, and that starter solenoid and motor can pull an amazing amount of current (due to it's gearing).

So, if the battery made a big difference I'd either look at maintenance or replacement (upgrade?) of the alternator.

[Mike Gerber]

I agree with everything Jeeves said except this:

"While the car is running, you can remove the positive lines from either the alternator or the battery and the car will keep running. Now, if you pull the line off the battery and the car dies immediately, it means your alternator is dead. Vice-Versa is also true."

This was a good test of the alternator years ago when there were no sophisticated electronics in cars. I did it myself back then. Today's cars have many sophisticated electronic components. These components can be ruined by the voltage spikes created by removing and reinstalling the battery cables from a running car. A better test of the alternator is to simply take the car to an auto parts store in your area that tests the alternator for free, while still in the car. Call around to a few auto parts stores in your area and ask if they offer this free service. You will probably find out that your alternator is very weak.

Mike