The 12V battery in my 2002 Prius is dying and when I took off the positive terminal cover to check, I noticed that there was a socket empty in the connector next to the battery (see photo below). Is this normal? If not, could it cause the 12V battery to drain excessively or not charge properly?
The measured 'parasitic' load is about 34-38 ma feeding the control computers and keyless entry receiver. Measure the voltage when the car is running, it should be 13.8-13.9 VDC. Bob Wilson
Thanks, Bob. I am charging the battery overnight and will measure the running voltage tomorrow morning. I am assuming that the empty socket is normal?
I charged the battery overnight. It wouldn't reach 13.8V even after 10 hours of charge so I know that the battery is dying but it was enough to get the car started. I performed the Vehicle Signal Check on the display screen and it showed the battery voltage at 13.3V while I was driving, which is lower than your recommended range of 13.8-13.9V. Is this expected given the dying battery or do I have a problem with my inverter?
I don't trust the display reading (personal preference.) I would recommend just put the car in "P" and read the voltage off the terminals. If it is that low, I would suspect the 12V battery is bad. Bob Wilson
I used a multimeter to measure the running battery voltage and it was between 13.8 and 13.9V. I replaced the battery with an Optima yellow-top and the car is running fine again. Thanks for your help!
