Third day with new car, dead 12V battery, second day in a row :(

My battery tested at dealer and with my equipment showed @350 CCA for a 285 CCA battery. If you don't drive the car for a day or more, the no load voltage drops from parasitic current drain. I have noted that occasiionally at night, the voltage spikes down few a few minutes for reasons I don't know.

 

Well, you can't really measure the CCA using cheap equipment. For one thing, you would have to refrigerate the battery.

 

Toyota dealer uses a fairly sophisticated battery tester. It provides a printout with details regarding battery condition, etc. Not sure what the equipment costs them. I have no concern regarding the condition of my battery. I tested with my electronic tester (Topdon) plus a tester that loads the battery for 130 amps for 10 secs. All good. I feel certain my dead aux battery back in august was due to the condition described in the TSB.

 

In any case, for the CCA measurement, you need to refrigerate the battery to the specified temperature.

 

I wonder if this is the computer phoning home for software updates?

 

Thank You !

 

Are there easily obtained obd scanners that read the battery sensor data?

 

NOTE: Also posted this in the Technical Forum

Yesterday, I charged the 12 volt battery with my Topodon charger in REPAIR mode. I believe this helps to possibly de-sulfate the battery. It took about 8 hours and ended with the battery reading 12.9 volts while on the charger at the end of the repair mode. Removed the charger and checked the battery voltage several hours later with my BT battery monitor. Voltage reading 12.79 volts. This morning I checked the battery voltage and it read 12.71 volts. Typically, I have been seeing a loss of less than 0.1 volt for an overnight. This would be expected from the dark or parasitic current that is constantly there. Toyota states a dark current of 120 milliamps or less is acceptable as part of their fault isolation procedure for a depleted aux battery.

Made multiple trips this morning. The first trip was short (about 10 minutes) and the battery voltage read 14.1 volts for 7 minutes of driving then decreased to 12.8 volts. The next trip was 14 minutes and I noted the battery voltage read 14.1 volts for about a minute then decreased to 12.8 volts. Basically same scenario on return trip. Summarizing, the battery voltage was at 12.8 volts for estimated 85 percent of my driving. After arriving home, let car sit for a few hours and then checked battery voltage to be stabilized at 12.57 volts. My experience has been that the battery voltage, i.e., charging voltage, while driving is predominantly at 12.8 volts from all my multiple observations. 12.8 volts is basically a battery maintain charge and I don't see it ever getting the battery to what would be considered a full charge.

I know from experience that very time you open the power hatch or a door the car wakes up and a drain on the battery for 10 minutes or more. I have confirmed this using an amp clamp on the negative battery terminal. If the headlights come on at car shutdown, the drain on the battery is quite significant. Thus, I no longer use auto mode for the lights. For my car, the last test I did indicated about 80 milliamps draw with the car asleep. This would account for the battery voltage slightly decreasing overnight.

One feature that sold me on the Prime was the ability to make short trips in EV mode. Looks like, from my experience, the aux battery system may not be up to the task. The number of dead aux battery complaints I feel is significant based on the low volume of primes sold to date. Toyota has a lot on their plate these days with multiple recalls across their offerings. Their corporate debt load is significant. The Tundra engine replacement costs are going to be monumental. The TSB for the prime cars regarding the depletion of aux battery if cable left plugged in is a puzzler. The use the term SOME cars. Well how do they know for sure that any car still could be affected ? The procedure in the TSB for the tech to determine the anomaly exists is not very clear as i read it. The warranty labor for the ECU firmware is 0.7 hours. I don't understand why Toyota didn't make it applicable for all Prime vehicles since the number of Prime cars delivered to date is relatively small. Pocket change in my opinion......

Cheers