If you havenít been monitoring the 12v battery voltage or its age (like I wasnít), this describes what to expect. Iím sure most of you already know this, but just in case some might not, it might be entertaining. It turns out this 12v battery from Walmart lasted 8 yearsÖnot bad. All below was during daylight so no extreme loads like lights, AC, etc.
Day one: First clue was that the Insight started on the 12v battery instead of the IMA battery (not enough 12v juice for the IMA contactors and other functions) and the 12v battery light remained lit after it started. Turning off and restarting caused it to start with the IMA battery and all functions were normal and it ran normally on yard sale stops and starts all day.
Day two: Plugged in a simple voltmeter into the accessory socket since I suspected an incoming 12v batt problem. Pre-start voltage was about 10.4v and it started with the IMA batt and got us to our first destination. After sitting in hot sun for a couple of hours, it would only start with 12v starter. The pre-start accessory voltage was now < 10v. 12v batt light was on. Drove it this way for what was to be a quick 20 min run to get home. The voltmeter indicated the DC/DC converter never charges the 12v batt as long at the batt light is on and it started with the backup starter. Well, donít try this at home
because this is what happens next:
As the 12v batt voltage starts dropping from about 9.8v to 9.4v, the ABS light turns on. About five minutes later, the EPS light turns on and no more power steering. Soon the dashboard lights dim; The Insight is dying after about 15 minutes. Pulled into a parking lot. Fortunately, since I already suspected the 12v batt was going soon, I was carrying a PEAK (or equal, of course) jump starter portable battery so I could get it to start on the IMA battery if needed. It was enough to start on the IMA batt and from here, all was good enough to keep going; dc/dc converter was running and time proportionally charging the 12v batt to keep all alive for the rest of the drive. Whew.
My lessons learned was 1. donít expect to go very far with the 12v batt light on even though you have an functional IMA batt. 2. Get it to start using the IMA batt any way you can if you need to go anywhere under this condition.
Oh, and day three. 12v batt replaced; all is good.