[shorod]

I'm not all that familiar with the electronics in an '89 Corolla, but they probably don't go fully in to standby until after several minutes (might take as long as 45 minutes). The 150 mA draw doesn't seem all that high if the measurement is before the car is completely in standby. Also, there is no way the 150 mA draw should drain a healthy battery after just a day.

It sounds to me like your battery has very low capacity. How old is it? If it's more than 3 years old, there's a good chance it's tired, especially if you don't desulfate it regularly and generally make short trips.

You could either take the battery to a parts store or automotive battery store to have them perform a load test, or you can perform the load test yourself. Since you have a meter to measure the current draw, I'm guessing you also have a meter to measure the battery voltage. Charge the battery using the charger, then disconnect the charger, install a volt meter to measure the battery voltage, then start the engine with the meter still applied. Monitor for the minimum voltage while the start is engaged. If it drops below 10.5 volts when cranking, that battery has low capacity. Continue to monitor the voltage once the engine starts. If the alternator is working, you should read a voltage of somewhere between 13.5 and 14.4 volts with the engine running.

Voltage potential and capacity are different with a battery. Just because it will take a charge and measure over 12 volts does not mean it can maintain that voltage when there is a significant current drawing (from the starter motor) on it.

My bet is on a weak battery and I think you'd be wasting your time pulling fuses to locate the 150 mA draw at this point.

-Rod