[Charleseasy]

Can you help. I have replaced batteries and alternator one after the other. One test at autozone says it is the voltage regulator .
Well no mechanic seems to find out. I had to recharge batteries daly!!
Some times I turn the light off and the car dies.
Thank you

[ma0641]

If you need to charge the battery each day, you have a short somewhere, causing the battery to ground and discharge.

[TxGreaseMonkey]

. Fully charge the battery. Static voltage should be around 12.8 volts.

. With the engine running, the regulated battery voltage should be 14 to 15 volts. If it's low, the voltage regulator is likely bad.

. Look for parasitic drain, if the problem persists.

[TxGreaseMonkey]

Battery Drain

Parasitic battery drain is the cumulative load produced by electrical devices(e.g., ECMs, clocks, security alarms, and radio presets), when the ignition isturned off. These items continue to operate, when the ignition has beenswitched off, and are becoming an ever increasing problem. Normal parasiticloads are below 75 milliamps (.075 amps). When parasitic load is greater than75 milliamps, batteries will drain even faster. Glove box, trunk, and underhood lights that do not automatically turn off when the door is closed, orshorted alternator diodes, are common offenders. Cooling fans, power seat beltretractors, radios and dome lights left on, alarm systems, and electric carantennas can also cause batteries to drain overnight. Leaving headlights onwill usually discharge a fully charged car battery, with 90 minutes of reservecapacity (36 amp hours), in a couple of hours.

Two methods are used to test for parasitic load (engine off, under hood lightdisconnected, accessories off, and vehicle doors closed):

1. The basic approach is to connect a 12-volt bulb across the positive andnegative battery terminals to test the bulb and battery. If it glows brightly,remove the negative battery cable and connect the bulb in series between the negativebattery cable connector and the negative battery terminal. If the bulbcontinues to glow brightly, start removing fuses or connections to the positivebattery, one-at-a-time, until the offending electrical component is identifiedby the bulb dimming.

2. The best approach is to use a DC ammeter, connected in series between thenegative battery cable connector and the negative battery terminal, or a clampmeter (set to DC amps), clamped around the negative battery cable. Startingwith the highest scale (or set multi-meter to auto range), determine currentload. If load is above 75 milliamps, after the initial surge, start removingfuses or connections to the positive battery post, one-at-a-time, until theoffending electrical component is identified by the parasitic load dropping to75 milliamps.