99 mazda protege battery light on
 

Hi all,
First post...Just got back from auto repair shop. Repair man claims battery light on because not all the alternator current is getting back to battery. System was checked with micro-vat ( I'm not sure I know what that means...) The results are as follows ( test says alternator failed....)
idle results
voltage 11.95 V
Ripple P-P 57 mV
current -14A
high Rpm results
voltage 11.54 V
Ripple P-P 41mV
current -10A

But I just had an alternator replaced about a year ago. Repair man says that may not be alternator...may be a computer component. what component is he talking about? He claims that the current may be held back from the batteryby this faulty component. Can anyone out there help? Thanks in advance.

RE: 99 mazda protege battery light on
 

Certainly does look like an alternator fault gdefig. Voltage is way low in the mid to upper 11 volt area. Should be 14-14.5 volts. Ripple voltage is ok. This is the amount of A/C voltage that is leaking past the diodes but those numbers look ok. Amperage is also very low. The component he is talking about is actually the engine controlcomputer. This computer directly control the amount of output from the alternator not like in the old days when a voltage regulator would do this job. Only real way to determine that one is to try a new alternator. If the one replaced a year ago was a remanufactured alternator it would be even more suspect.

RE: 99 mazda protege battery light on
 

Thanks for the reply. I'll try the alternator although I was trying to avoid the costs. More on this later.