2000 insight with 110K miles. The 12v battery is dead, the main battery is working, though usually only shows 1/2 charge, but fully recharges with my 40-mile interstate commute. Usually experience a recal couple times per week. Is there any reason to buy a new 12v battery? Car is running fine except the occassional jerky ride which probly indicates need to clean EGR. Getting 60mpg with passenger, 70mpg alone. No mods other than cardboard air damn at radiator.
Hi Modelman; Yes, you absolutely need to replace your 12V battery! You say it is dead. Experience has shown that performance of the 144 volt pack and the entire IMA is heavily dependant on an excellent, strong 12 volt. The ground straps are vital, too, and have been an issue. Please search "modifications and technical" as well as "problems & Troubleshoot" for threads concerning these topics. In fact, several have fixed their perceived "problems" with just a 12 volt replacement!...........
Many Insighters have the same misconception. the 12V is required for pulling in the HV contactor else the 144v pack will _never_ be engaged :!:
And there's still a complex and possible interaction between IMA load and the DC-DC converter. It uses some of the 144v generated in the IMA motor and drops it to 12v for the conventional electrics.
One possible scenairo is that a 12v near its demise drops low v enough that the BCM resets (effectively a manual recal) and your in a forced charge on start-up.
Another is if the 12v fails in an unusual fashion. Sometimes the internal resistance of a 12v can drop dangerously low. Plate bridging or heavy sulphation are two of the possible causes. Then the 12v charging system incorrectly "sees" the need for more current, drawing a heavier load in the IMA system. In a car with a conventional charging system the alternator frequently melts down.
But from the many reports in here the 12v is prematurely replaced. Sometimes the BCM can drift into the SoC doldrums for days - weeks at a time. A reset is all that's needed. Disconnect the 12v or
And IMA batteries will eventually exibit a more fragile SoC and more frequent recals. Its just the normal part of their aging process. Their probably still "good" for many tens for thousands of miles. You'll just have to live with the lower MPG due to the more frequent forced charging or _choose_ to replace them prematurely. Warranty will only cover them at their predetermined point of failure as defined by an IMA code (the red IMA light on the dash comes on while driving).