My battery is on it way out. If left for a few days without use, I will not start the car. However, if the car is used daily it will always start but the swing is generally slower. I am also now getting slight breakup on high rpms.

Could the bad battery be causing this? The data logs shows over 13 volts up to about 6500rpm, then it will fall to about 12.2 volts by 7500rpms. This is the point where I will be getting the break up. The alternator seems to be charging ok.
Could the battery be the cause?

Has any one had ignition breakup due to a failing battery?

 

Only if it has an internal short and is loading down the alternator too much.
The battery is used only for starting or if the alternator is failing. The rest of the time the car runs on the alternator. If the DC load is so great that the alternator voltage drops down equal to or less than the battery voltage, then the battery will start to discharge.

 

Check your alternator.

 

Its wierd that you posted this, I was just about to. My car has been breaking up in the higher rpms. This past weekend I was installing my LC-1 and had the radio on in the car while I was doing it. After about an hour my amp shuts off and Im pondering whats going on, an hour at low volume shouldnt kill my brand new battery. I put it on charge and finish my install. About 3 hours later I go for a ride and its not breaking up anymore. Volts show 13.5-14.

Today on my way home from work I get on it and it breaks up again. Volts are 12 at idle and go upto 13.5 upon acceleration.

Brand new battery and brand new (stock S4) alternator.

 

get alternator upgrade,, S5.
it puts out 14.4 or higher, works great with the elecs. in the whole car. max around 14.8

13.9 or lower,elecs. dont like it!

 

Check the cable going into the Alt. mine came loose and killed my batt.

 

all of the above are on target.... you should also check belt tightness... perhaps high rpm slippage. somewhat improbable but possible and easy to check.

 

Thanks for all the suggestions. The slipping belt theory sounds very plausible. All my recent logs (20+ for the past few months) show a volt drop at high rpms, then the instant I let off the throttle the volts goes back up and stays up even at those rpms during decel. Also my alternator belt is not as broard as the factory belt since I could not find a shorter one with the stock width when I deleted the air pump.

Thanks again

 

Banzai should have the belt you need. They stock an assortment of different length belts in the proper width.