phb10186 wrote:I normally take a pic on my smartphone now before I take a car in for service. Proof that all the lights are off!
That's an excellent practice. I also put small chalk marks on the sides of the tires when getting wheels balanced, aligned etc. This way one can tell whether tires were moved around the car in the process.
Seems like a lot of the anomalous behaviors reported on the forum end up going away with attention to the 12V battery.
Without exception Lead acid (and most other chemistries) have rising internal resistance with age. Cold cranking amp tests are not a good benchmark for battery health. Basically that test equipment does not care how low the battery voltage sags as long as the amps are delivered. The I miev is sensitive to voltage from the 12v system. There are no "high cranking amps" but there are much shorter capacitor charging amps. To catch the peak would likely require an oscilloscope. If the voltage breaks the low bar during the "start up" then errors will result.
Also it isn't the cranking loads which keep ICE cars batteries better exercised as far as plate deposit cleaning goes. It's the high amp charge rate that the battery sees from the alternator after the cranking loads. So if one wishes to keep a "float" battery in better order one would discharge it to around half and then recharge at high amperage. The I miev DC to DC converter is more than capable of doing this with 60 amp charge rates available for the 12V battery while charging the car, or while in ready mode. The problem is that the high load on the 12V in an I miev is extremely short So the SOC of the 12V battery is not low enough to accept the high rate charge amperage. So it gets precious little vigorous exercise. So internal resistance rises undetected until these intermittent faults show up. In an ICE it would be more apparent because the cranking speed of the engine would slow and sound a bit labored with excessive voltage sag. Such a battery would pass a cranking amp test. But not sound strong staring the car.