i was wondering if anyone would know why my battery wont seem to hold a charge, i got my alt tested and they said it was doing fine but when a load was put on the battery the reading went way down. its not a bad battery because i just got a new one and still same problems. plus now my oil dummy light just came on today when i went to start my car, but it is right at the full line. but the battery problem is really irritating so if anyone can pass on some knowledge i would appreciate it a lot.

 

Well, I had a similar problem on my brother's 1st gen when the one of the fuses went out. The alternator just wouldn't put any power out. Start your car and then diconnec the (-) battery cable and see if it runs off the alternator. If it dies right away, then obviously the alternator is not supplying power.

 

Your alternator isn't properly charging the battery. The best bet would be that the alternator is crap.

Alternator test (thanks to Sureshot)
Engine running, headlights & heater fan on high:
Alternator post to alternator frame = 14-14.5 volts (verifies the alternator output)
alternator post to battery (+) = 0 volts (verifies the primary + wire)
alternator frame to battery (-) = 0 volts (verifies the primary ground)
Turn off the motor, but leave the lights on.
Battery (+) to battery (-) = ~12.5 volts and holds steady. (verifies battery)

Don't do this. On an S4 the battery is used as a capacitor and if you bypass it then you can fry the ECU.

 

hey thanks for the replies, i'll try it out tomorrow

 

I used to have the same problem, i was thinking it was my battery or alternator but it ended up that my motor was flooding itself out while it was sitting for short periods of time. what i did was hooked up a fuel cut off on the power line going to the fuel pump. instead of turning the car off with the ignition i would flip the switch to off and my car would die. ever since then i havn't had any problems with the car starting. but if you say the battery is low then its obvious it was the battery. i would do the fuel cut off switch regardless because its a good antitheft device and it might just solve your problem

 

wow thats a good idea because im pretty sure my car does flood itself to, and its not my battery i just found out. the battery is a little weak but all my lights and everything work. so i concluded that the starter is just not getting power. so when my driveway has room i'm going to jack up the car and take a looksy. i hope i dont need a new starter though.