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2011 Curious if it might be some temp sensor somewhere instead of the high power battery degrading?

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Things here have started to warm up a little here. Yesterday it was 50 degrees outside and the car started in battery mode and never shifted to using the engine to make poser.

Like in the past as the weather warms up my Volt goes back to battery most of the time. I realize that when things get cold the electric mileage goes down because of heating, lights and wipers using power and understand that. But the last couple years even with a full battery it runs the engine most of the time when it gets cold outside. I have thought it was just my high power battery getting older (11+ years now).

But having a full battery and the car starting the engine running right away would not be because of a used up battery. This usually happens when the outside temp is colder that 50. It would appear to me that that there is something that is colder and needs to heat up like the main battery because after running with the engine for a while she can shift from the engine running to using the battery even when it is a little below 50 outside. Could this be some sort of temperature sensor not working correctly or something like the heater for the battery not working correctly?

Just wondering what those of you that know about these things can teach me.

Roy 2011 volt #1019
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Ryan, I have the dongle and MyGreenVolt app ( I do not see the My Volt Control app in the app store is it the same?). Can not find where to see if battery heater is active or working in what I have?
first screen ("dashboard"?) has four temperature bars: battery coolant, engine coolant, powertrain electronics coolant, and transmission/driveunit. At some point below 32F battery temp, the engine will run continuously to generate power to supply the battery heater. At an even lower point, there will be an alert "Battery too cold, plug in to warm". One indication that the battery heater is working is that the battery temperature will start climbing when you turn the car on. If it starts approaching 50 in less than 20 minutes from 32, that's normal operation.

Normally, the battery heater will keep the battery at or above 32 by drawing wall power. But depending on the model year, it may only do that for three days and at which point it enters a deeper sleep until it's unlocked and started. MGV's dashboard pie chart shows battery heater consumption as yellow. If that wedge is a substantial chunk, that means the heater has been working. that chart seems to be "since the battery finished charging to full" so when the car turns on, you'll see what was used while it was off and any preconditioning you called for, then as you drive, the green propulsion energy segment will start overwhelming battery heat and cabin heat sections.
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Okay, this MAY BE relevant sometimes. I did an experiment on Saturday.

Somewhat cool day below freezing, but barely above ERDTT, but hadn't used the car for a couple of days and the battery was cold. I rigged up MGV and the battery temperature read out as 32F. Which is where a plugged in but resting Volt seems to let it drop to. I've never seen it colder until I've not driven for at least three days and the car falls into an even deeper slumber. OnStar stops polling around then too. I'd been niggling about "why are we seeing all these engine running events in winter?" so I wanted to see if I could make one happen. Got the car out, popped on Mountain Mode just as a charm against wrecking the battery, headed for the interstate and punched it.

I got the engine to turn on. No dash message, no ERDTT, no Propulsion Power Reduced, just engine on when there was theoretically plenty of power available. But the battery temperature meter was RED instead of green and it was climbing quickly. 2-3 degrees per minute. Which is a LOT for heating up a 300lb lump. After about 10 minutes the temperature in the battery was up to just above 50F and the meter turned green and the engine turned off and I was back on battery, using charge down to the mountain mode setpoint*.

The point being, though, that the combination of trying to climb up a ramp and barrel down an interstate at 75 with a freezing battery WHILE feeding the battery heater full blast seems like it was just too much for the chemistry to keep up with, and the Volt responded with "Well, I guess I need more power" and kicked on the ICE. The car performed well while doing this, and the engine spun quickly (3200-3500 RPM) though not what I'd associate with "screaming". Most of normal driving may not even use the battery heater and just depend on the intrinsic heat of "battery being used" to warm it slowly up to the point where it starts chilling the battery instead.

* Mountain Mode for early Volts like mine was documented to be "about 40% battery" in song and legend, but for posterity I watched it cycle between 37% and 39% State of Charge. That's surprising little room between the low and high marks corresponding to engine on and engine off, but it does match pretty well with the 5%-7% range SoC I see on normal CS mode. Which makes me further suspect that all the car is doing is changing where "CS" is for MM, and probably doing the same thing for Hold Mode, and in the latter case, just setting the high "engine off" threshold wherever the SoC was at the time Hold Mode is turned on.
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Wonder if I am the only one that would buy a real new battery not rebuilt with old parts if it was available and less than $10,000 installed. I understand that batteries have a life span. I would pay it if that would get me back to an electric car with gas range extender since I got 11 good years before the problem started.
A LOT of people would buy such a battery, but ... it doesn't exist. And there's no sign that it will, in spite of that unfilled need. It's not impossible to design (GM did it), it's not impossible to manufacture (ditto), that basically leaves as a reason why not: It's infringing on Intellectual Properties or there's no profit in it. And I'm sure GM would love to have someone offer to take on the work in exchange for selling them the batteries so IP is probably just a matter of contracts. Which leaves "no profit in it."
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