TenthYear

iTrader: (1)

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.

Enthu

iTrader: (1)

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.

My5ABaby

iTrader: (7)

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.

TenthYear

iTrader: (1)

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

RE TurboII

iTrader: (2)

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

TenthYear

iTrader: (1)

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.