Car batteries affecting power output (kw) and performance

[Spyda]

A flat battery shouldnt have much effect on the ignition coil as the car runs off the alternator when it is on. The battery is only used after the current drawn is greater than the current avaliable from the alternator.

[Ben_GTI]

A flat battery shouldnt have much effect on the ignition coil as the car runs off the alternator when it is on. The battery is only used after the current drawn is greater than the current avaliable from the alternator.

Depends on how good your alternator is.

[Spyda]

Depends on how good your alternator is.

what?

By having a good alternator i asume you mean the alternator is in good working order and is capable of producing the correct amount of current.

If you alternator is not working than its just what i said, the current drawn will be more than your alternators output and then your battery will be in used.

[Ben_GTI]

Yea dude, hence I'm just pointing out that buy getting a new battery you could be fixing the symptoms, not the cause of slightly less power.

[Lomo]

I've been trying to diagnose faded power and increased fuel consumption on my Subaru Impreza for the past 2 years. Over that period I've changed the oxygen sensor, cleaned the MAF, replaced the temp sensor and changed the timing gear, always expecting the car to get the power back I remember it had when I bought it from my mate. I was just about to remove the injectors for a clean when the batt started to die and so I replaced it. The car has finally gotten it spirited feel back, sooo much more power, 10% better fuel efficiency and the auto gearbox changes so much more quickly. It's like a new car again

The car has had its ECU reset numerous times and it didn't change a thing. After talking to two mechanics about this amazing recovery they both said that modern cars are very sensitive to voltage drops which messes with sensor outout. The voltage drop occurs as the battery ages and thus increases it's internal resistence meaning that the alternator can't deliver its full potential.

If youre worried about voltage drops you could always do a grounding mod which is very popular in Subarus. Pretty much running a grouding wire form the Neg batt terminal to every place on teh engine where sensors are located thus reducing voltage drop introduced by corroding engine pathways etc.

BTW If you're after a batt, find a Bosch distributor and get yourself one of these, cheaper than other batts and they're maintenance free

[Lomo]

Dyldo, one thing that might help you in diagnosing a batt problem is that the car runs well in open loop and only loses power in closed loop once the car engine comes up to temp. I definatelly had these symptoms which is why I replaced the oxygen and temp sensor thinking that they were to blame.

[gldgti]

if the alternator is dying, the battery is providing the power for the coils and the plugs don't work as well as they should. Hence you get less power because the fuel isn't being ignited as well as it could be.

bingo.

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