Extreme COLD battery management

[thinair191]

I live in SE Michigan, and for the past couple of weeks the mornings have been very cold, one was as low as -20 not counting wind chill. Only the -20 day made the car start rough, but only sounding sick for about 5 seconds.

I have observed a change in battery management when the ambient temp is about 10 above or less. After accelerating using assist, the system immediately goes into a forced charge indicated by 3-4 bars on the charge indicator. This does not stop until the battery SOC is ALL the way to the top. I seldom ever see the SOC fully charged, it usually stays about one or two bars from the top.

This is not a normal Re-Cal, it doesn't matter how small assist is used, it will force charge back to full each time until about 10 minutes into my trip when things have warmed up a bit more. Even when the SOC is full if I use assist for more than 3-5 seconds in force charges for an equal amount of time.

Has anyone else experienced this? It seems to be programed to do this in extreme cold. Does the cabin temp have anything to do with this, seems to go away when I get things warmed up inside.

[joecvt]

This is perfectly normal in cold weather conditions and while the IMA battery is still cold. I live in NH and experience the same thing. It actually does this even when temps are close to 32 degress but it does not always show the actual charging on the gauge (hidden charge).

It is basically applying a small charge to the battery to warm it up. If you notice, you have limited regen while in this mode as well. These are some of the routines in the firmware not to use the battery too much until it is warmed up.

MPG goes way down because of a cold ICE engine, winter gasoline and a forced charge until warm.

JoeCVT = Just your average CVT owner

[Dougie]

Maybe it is putting a heavier load on the engine to get the catalysts warmed up...

[joecvt]

Originally Posted by Dougie

Maybe it is putting a heavier load on the engine to get the catalysts warmed up...

Just like any other newish car, the high idle in cold conditions helps bring the catalytic converters up to peak operating temps.

Here are some other references that mention the IMA charge on the battery in cold temps:

http://www.insightcentral.net/commun...t=8282&p=73333

http://www.insightcentral.net/commun...t=5790&p=53183

JoeCVT = Just your average CVT owner

[Insightful Trekker]

FYI,

While CATs are part of the modern equation cold fast idle predates them by many decades.

Internal combustion engines, especially liquid hydrocarbon ones perform quite poorly until reaching operating temperature. (180-195F coolant temp)
Power, economy, wear and emissions are all worse than with a fully warm engine.

HTH!

[joecvt]

Originally Posted by Insightful Trekker

FYI, While CATs are part of the modern equation cold fast idle predates them by many decades.

Agreed....I only metnioned that fast idle helps warm up the cats quicker in replying to the previous posting. Kind of like an added benefit. It was not my intention to indicate in my counterpoint that fast idle only exists for catalytic converver warmup.

JoeCVT = Just your average CVT owner

[thinair191]

It was a curious condition, but seemed to be a computer controlled situations. Always happy to know that my car knows more than me