More unusual IMA behavior?

[nemystic]

After driving an Insight for over 6 years, with only the stock IMA system in control, I'd only seen the 100% iSoC (indicated State of Charge) 3 or 4 times, and in each case, the weather wasn't particularly cold. This would be where all of the green bars are illuminated.

Earlier this winter (before I began all-temperature bicycle commuting) there were many mornings with temperatures between 0 and 10 degrees F. On several occasions on those cold mornings, with only the stock IMA system in control, I saw forced charging continue to the "all bars" indication. I could see that the forced charge was in effect by the non-stock instrumentation that I have.
(Because of regen - and sometimes assist limitations at those temperatures, manual control doesn't necessarily enable improvements in fuel efficiency until things get warmed up a bit.)

It's assumed that the Insight battery controller doesn't normally charge or discharge the battery pack to the extremes, so as to increase the life expectancy of the NiMH batteries. I recall seeing some information that the early Insight control systems could allow "overcharge" of the pack. My Insight does fall into that "early" category.

What leads me to believe this "all bars" charging situation is unusual is that I hadn't seen it in previous years, with about 90%+ of the car's total mileage being accumulated at that time.

Perhaps the "all bars" charging condition is normal in cold weather? I trust that observant, fellow cold-weather Insighters will weigh in on this.

It's possible that the reason I hadn't seen this previously was that before the winter of 2006/2007, the car had always started the daily commute from a subterrainean garage that was almost never below 40 deg. F. In the subsequent winters, my Insight has been out in the cold, with the battery pack equilibrating to the overnight temperatures.
Last year was a mild winter in this area, enabling bicycle commuting for all but about 25 days that were bitter cold. I don't recall using the Insight much during that time.

As another reminder; the iSoC doesn't necessarily represent the actual SoC of the battery pack.

In summary; I'm interested in finding out if the "all bars" indicated State of Charge is a typical situation for the Insight in cold winter conditions?

[joecvt]

I leave the Insight outside (I live in New Hampshire) and on very cold mornings (even when not cold enough to use the typical starter) I see a force charge of a couple of bars to warm the battery pack. Nearly 99% of the time, my SOC is only one bar down from the top when I start the car. When this force charge is going on, the last bar will light. Even when the green bars of force charge go away, there is still some background charging going on to warm up the pack further. Mind you, this was starting out in the morning with only one bar down from the top.

How can I tell there is still background charging going on you ask...I still have one of the first designs of Manual IMA installed in my car with pedal activation (serves a dual purpose). If I push down just slightly on the pedal to power up the unit and before any relays engage, the green bars will appear on the gage again whenever background charge is occuring. Kind of a nice unexpected "feature" that I found out during the pedal adjustment process

JoeCVT - Just your average CVT owner

[nemystic]

Thanks Joe,
So it would seem that battery warm-up takes priority up to the "absolute charge limit" (which we can't see on the stock display).

I'm curious to know if the battery warm-up function is primarily to help them operate more efficiently, or otherwise to preclude or minimize possible damage, potentially due to thermal imbalances?

With regard to the background charge, I certainly agree that it's good to be able to see when it's happening, and even better to be able to turn it off temporarily when it's counterproductive to overall fuel efficiency.