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I've been meaning to post this for a while and keep forgetting... This past winter, I took the Volt on a trip where it stayed overnight in about -5F temperatures (battery fully discharged), and then I used it the next day to run some errands.

Not "super" cold, but the results were still telling. First, the Volt seemed to do its engine running when battery is too cold behavior, the point beyond "ERDTT" where the engine is essentially coupled to the wheels and bypassing any battery use. Eventually, that went away and the engine would stop when I was stopped. This mode has been fairly well documented here and elsewhere.

However, the other behavior I observed was that, for the majority of my driving during those errands, the battery did not want to take energy from regenerative braking. I could be going down a fairly long hill, after the above "too cold to use the battery" operation ended, in Drive, and the engine would turn off, but putting the Volt in Low would cause the engine to idle quite high and I don't believe any regenerative braking was taking place.

There were other small oddities as well, and because of the presumed lack of regenerative braking and more-than-normal engine idling, the MPG was actually pretty poor, I'd say considerably less than the 32mpg city rating.

I think it's an example where the Volt does not shine, but one that is typically not seen often if people plug in nightly as prescribed, which not only keeps the battery charged, but also keeps it conditioned from a temperature standpoint.

I'll try to remember to elaborate a bit more and also post a screen capture of the energy usage. It's in my camera somewhere...
 

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Interesting, did the Power Flow screen show any regen?
 

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Besides the described behaviors, was the drive-ability impacted? Did it have less power or force you to wait to begin driving, etc?
 

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That's interesting. I've had my Volt parked overnight unplugged in -15F weather on a few ski weekends and not experienced anything besides ERDTT when getting it going again. No problems starting up, no errors or warnings. Regen normal. I can imagine if it was parked in -20 or -25 for a few days it might get into some too-cold scenarios, but overnight wasn't enough for my car to do anything unusual.

Driving my Volt in mid-winter I had one week of commuting where I wasn't able to plug in at all (some work being done blocked my plug at home). I think I averaged 27 MPG that week. Lots of stop and go, temps never got over 10-15 degrees.
 

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Besides the described behaviors, was the drive-ability impacted? Did it have less power or force you to wait to begin driving, etc?
My experience is the feeling is much more like a typical gas car. Everything was fine, but you lose any battery boost. Feels like you are driving an 80 hp car with a CVT. Not exactly pleasant compared to typical Volt (feels more like cheap econo box).
 

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The "deep cold ERDTT" is particularly noticeable if you have ERDTT disabled, as all of a sudden the engine starts and you thought it was disabled :) This makes the difference harsher. If using normal ERDTT you might not even notice the second variant is there, which is based on battery temp instead of cabin temp.
 

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Discussion Starter #7 (Edited)
Interesting, did the Power Flow screen show any regen?
Sadly, this was with my wife's 2012, which lacks the detailed power screen in the driver's console of my 2013 Volt. The center console said regen but that's just a four state screen and I wouldn't trust it in this more unique scenario, as the other alternatives are that power is being supplied by engine and/or battery, or power is off, and none of those are really accurate/applicable either.

That's interesting. I've had my Volt parked overnight unplugged in -15F weather on a few ski weekends and not experienced anything besides ERDTT when getting it going again. No problems starting up, no errors or warnings. Regen normal. I can imagine if it was parked in -20 or -25 for a few days it might get into some too-cold scenarios, but overnight wasn't enough for my car to do anything unusual.

Driving my Volt in mid-winter I had one week of commuting where I wasn't able to plug in at all (some work being done blocked my plug at home). I think I averaged 27 MPG that week. Lots of stop and go, temps never got over 10-15 degrees.
If you experienced ERDTT, that implied you had some battery charge left, unlike me. I'm not sure if that would change the behavior, I wouldn't expect it to but our different experiences suggest otherwise. I was admittedly surprised that what I experienced happened at a seemingly "warmer" temperature, but again, the uniqueness may be the combination of a drained battery and not being plugged in. I'm not really sure. I suppose it's also possible that it was colder than I thought. It may have been windy, and that could be relevant as well?

Besides the described behaviors, was the drive-ability impacted? Did it have less power or force you to wait to begin driving, etc?
No, it wasn't cold enough to force me to wait or anything like that. The drive quality was initially impacted slightly by the engine being "directly" coupled to the wheels through the electric motor, and in that case you basically have the horsepower of the engine, there is no battery to buffer the power and the engine RPM follows the demand curve instead of lagging it. But other than what was described in my OP above, there were no other differences.
 

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That's normal for the deep cold running due to battery temp mode. See thread in my sig.

The battery is too cold to give or receive more than a handful of kW, so the engine is doing all the work. Once the battery is warmed up, the computer will allow more and more power in/out until the point it can resume normal buffer mode, with the engine coupled to the buffer SOC as opposed to real-time pedal demands.

The volt may not shine, but neither will any other ICE. Terrible response, terrible MPG, and just overall bad in extreme cold conditions.
Once both have warmed up, both operate normally. (I'd actually say volt operates better as no transmission lags trying to shift in near-frozen sludge)
 
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