2004 12v aux battery part number

28800-21170 is the correct battery, MSRP of $174.
ToyoDIY.com

Considering freight cost for this very heavy item, you may do better calling the various dealers within a reasonable driving distance to see if you can get a better price locally.

 

Pls let us know your final price on the battery, shipped from San Diego.

 

12.3V is not bad, BTW, since the battery is under some load when the car is ACC-ON. My plan is to replace the battery on my 2004 as a preventive move after it is six years old, or at the end of 2009.

When you've successfully ordered the battery and have the final price pls let us know. Shipping a hazardous item might cost more.

 

Actually according to Toyota, 12.3 Volts is considered to be discharged. I just checked my owners manual too! But it does mention it should be checked in 20 degrees celcius temperature. So a slight drop like that in cold weather could be fine.

 

For ease of reference, I numbered your points. I would say that #2 and #3 are likely caused by a bad fob battery, so if you spend $5 at your local drugstore you can take care of those two problems.

#1 is mysterious. Do you have an aftermarket alarm system installed?

 

If you measure 12.3V when the car is IG-OFF and the correct ambient temp is available, then I would agree that the battery is around 50% SOC. However romad measured that voltage when the car was ACC-ON, so that probably corresponds to an IG-OFF voltage of 12.5V or better.

 

To provide another reference point, my 2004 was manufactured in 1/2004 so the battery is ~5 years old now. Ambient temp this morning was 48 degrees F according to the MFD. Using my Fluke DMM, I measured IG-OFF voltage to be 12.3V. ACC-ON voltage was 12.0V. I would say that these results would be typical of a battery of that age, it still works but is certainly not in new condition.

When measuring battery voltage, you should wait at least one hour after turning the car IG-OFF from READY, so that any "surface charge" on the battery can dissipate before your measurement. Then if you want to measure ACC-ON voltage, do so prior to making the car READY.

 

This is OK as long as you keep in mind the MFD reading may be slightly off (compared to using a good digital multimeter), and you do the measurement after the car has been IG-OFF for a while, so that the true battery voltage can be measured.

 

I don't suppose they told you what their over-the-counter price would be?

Usually I buy my Toyota parts via weborder from Champion Toyota in Houston. I eventually will need to buy a battery; Tustin Toyota seems to be the best place locally. However I wouldn't mind driving to San Diego if the price made it worthwhile - could combine some tourist activities with a battery purchase...