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Discussion Starter #1 (Edited)
Hey all. Have been working on finding the "magic" precondition routine for my wife's daily commute. Usually hit it the first time at around 6:45AM, and then a second time at around 7:10 in preparation for her 7:15A departure.

However, I realized that the first precondition is using NO grid power from my L2 charger. I have a whole-home power monitor that shows our consumption on a per-second basis and when I hit the precondition the first time I get the confirmation from the OnStar app, the car does indeed go into precondition, but it's using 100% battery. Upon completion of the first precondition, then it immediately starts charging (and I see that reflected on my power meter), but having used about 10% of the battery for the precondition it's taking over 20+ minutes some mornings to recover, meaning that when I hit the second precondition it's often still not even recovered from the first one...but if it's at least still charging from the first one, the second precondition seems to use grid vs battery.

I was under the impression that if grid power is available the car would use as much of it as possible (~3KW), with the remainder required coming off the top of the battery to meet the 6KW heater demand. As it's stands now the car is using zero grid at all during precondition, only drawing grid after it's complete.

I have made sure that the time/rate settings are adjusted on the car so that they shouldn't be having any effect on the cars willingness/ability to draw grid power - the fact that it happily starts charging right after the precondition is done is suggestive of the fact this isn't the issue.

Thoughts?
 

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Discussion Starter #2 (Edited)
Ok, this is weird.

After thinking about the issue a little more, and for the purpose of experimentation, I changed (via the OnStar app) my charging preference to "Immediate" vs it's usual Departure Time/Rate setting.

After I confirmed it had changed, about 10 minutes later I sent a precondition command...and boom, it started drawing the max my L2 will supply, as shown on my whole-home meter showing a sudden 3+KW draw increase. It's definitely the car, no question.

So, it appears that the departure time/rate setting IS actually effecting things somehow. But why then is it refusing to draw grid power between 6-8AM when the car is programmed to charge during off peak, and also programmed to have off-peak until 8AM?

Edit: It just finished the precondition, and OnStar shows that the car used only 4% of the battery as opposed to the 10-12% when it's doing a precondition without drawing on the grid.
 

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Maybe because preconditioning always draw power from battery and via schedueling you said "not to charge"?
 

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I have never had my 2011 Volt pre-conditioning take power from the battery in preference to the 240V EVSE. But then, my charging is always set to immediate. So you may discovered that Immediate is required to use wall power.
 

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http://gm-volt.com/forum/archive/index.php/t-26505.html

Neromanceres
02-08-2013, 01:42 PM
Preconditioning can still use battery even with the 240v charger. It's just a question of how fast it gets put back in.

Correct.

On 240V the Volt can draw 3.3KW of energy from the wall. On 120V (on 12A setting) it can draw 1.4KW max from the wall. Yet the heating system in the Volt can consume as much as 7KW of electrical energy. The balance comes from the battery in both situations. But obviously the car uses less from the battery and recovers the charge much faster using 240V.
 

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Discussion Starter #6 (Edited)
I have never had my 2011 Volt pre-conditioning take power from the battery in preference to the 240V EVSE. But then, my charging is always set to immediate. So you may discovered that Immediate is required to use wall power.
That's just weird/wrong - our off peak electricity is less than half the cost of peak so obviously I want the car to lean towards that when possible (Hence the programming to prefer rate vs immediate), but I don't comprehend why even though the car is programmed to tell it that the rate during the precondition is "off peak", it still refuses to use any of it.

This appears to be a programming bug...and I can't believe nobody has discovered it thus far?

The thing is....I wonder how many others are having the same issues with preconditioning but just don't know it...because they don't have the ability to see their homes grid usage like I do.

Preconditioning can still use battery even with the 240v charger. It's just a question of how fast it gets put back in.
I covered this in detail in my post - it's not that it's drawing from both the battery and the grid when plugged in (That, I'd expect), it's that it's drawing *nothing* from the grid when plugged in during precondition unless (apparently, I discovered) I set the charge preference to "Immediate".

Maybe because preconditioning always draw power from battery and via schedueling you said "not to charge"?
Again, covered in my post - not the issue - the schedule programmed into the car shows my off-peak electricity period extends to 8AM, so it shouldn't be effecting the cars willingness to draw from the grid in the 6:30-7:30AM time period.
 

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You said you changed the charging time to immediate from departure-based. What time was the departure-based time set to, and has the car been driven since making that change? (Some settings don't take effect until the car is cycled on after changing and we don't know when an OnStar-effected change to charging cycle gets written to the car configuration -- that may not happen until the car gets turned on either.)
 

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Discussion Starter #8
It’s typically set to departure/rate due to the drastically cheaper off peak rates. My wife usually arrives home around 5:30pm and plugs in then which is square in the middle of our peak winter electricity rate period, so I typically discourage charging then unless we are going back out.

The rates programming is setup to ensure that morning preconditioning happens on an off-peak period which the car is programmed to utilize.

I don’t really care about departure time that much, but I have it set up 7:30am so my thinking is that it shouldn’t effect anything.

I changed it to “immediate” charging last night before testing things and the precondition behaviour changed immediately - didn’t have to drive it.
 

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I think this is caused by how the departure time/rate setting works, as you suggested. Obviously you found that the "immediate" setting makes the preconditioning work as desired, but then you have a rate problem.

My suggestion is to experiment with the other of the 3 settings, the one just for departure time. I think it will make the preconditioning work as you want (not positive). You should also be able to set it so it only charges during your off peak time, since you only need about 4 hours to charge and it will only charge immediately before your departure time setting (in other words, it will not start charging when she gets home in the evening).

I would try setting it for 6:45 am. You would think that setting would not allow it to charge again during later preconditioning, but it suspect that it will. Worth trying it out.

Another possibility is that your current setting of time/rate will work if you make the departure time setting earlier, say 6:45am. Good luck!
 

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I have never had my 2011 Volt pre-conditioning take power from the battery in preference to the 240V EVSE. But then, my charging is always set to immediate. So you may discovered that Immediate is required to use wall power.
I have noticed that when I have it set to delayed charging (no rate stuff, just based on departure time), my Volt will NOT pull from the grid with a remote start, but it will with it set to immediate, which is kind of unfortunate though not entirely unsuspected. This is true even if I do a charge set to temporarily be immediate; once the charge is complete it seems to go back to delayed for the purposes of a remote start, since it won't pull from the grid.

The rate-based settings seem like a bug, if it's supposed to charge during that time you'd think it would pull from the grid. Although if it is supposed to be ready by a certain time, it may not pull from the grid until needed to meet that deadline.
 

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Well if your rate is too high for car to charge, why would it pull from grid to heat? I kinda agree with this logic, thou it would be practical for an option to be added in menu for user to choose.
 

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Discussion Starter #12
I have noticed that when I have it set to delayed charging (no rate stuff, just based on departure time), my Volt will NOT pull from the grid with a remote start, but it will with it set to immediate
Yeah, this is exactly what I'm experiencing...glad I'm not alone on having noticed it.

The rate-based settings seem like a bug, if it's supposed to charge during that time you'd think it would pull from the grid
I agree, this does certainly seem like a software bug.

Without doubt it has a lot to do with why some are experiencing drastic winter mileage drops - they think they're doing themselves a favour preconditioning their car, don't realize it's not actually drawing any grid power at all (face it, unless you are being extra observant of your OnStar battery percentages before and after a precondition, or you have a whole-home wattage monitor, you wouldn't even know), and in the end they might as well have just went out to a cold car, got in, and drove away without preconditioning - arguably it might have actually been *more* efficient in the end as all they've accomplished is killing 10-12% of their battery for a bit of heat, while having gone 0 miles during it.

Anyhow, I'm going to experiment more with the departure/rate settings, but it'll have to wait a few days - we just hit a cold snap this morning that's going to have us firmly in ERDTT until probably Thursday or Friday.

Well if your rate is too high for car to charge, why would it pull from grid to heat? I kinda agree with this logic, thou it would be practical for an option to be added in menu for user to choose.
I've mentioned several times, this is occurring even during rate periods where the car knows very well that electricity is off-peak.

It seems increasingly that this is a bug. A rather big, nasty one, at that. I'm still amazed nobody's noticed it until now?
 

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Discussion Starter #14
Sorry I always use it when at work which means "immediate" mode for me.
No prob. The bug doesn't seem to present when the car is set to "charge immediately", but short of upgrading to an EVSE that would control charging times (to favour off peak rates) vs the car itself, I'm not sure there's away around this.
 

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If you work out the formula, I'm happy to do the opposite :)

Mine always draws power during preconditioning. As I'm not an early bird, we're into peak time by the time I am getting ready for work. As I don't use the full battery, I'd be perfectly ok with it not using grid power after 7.

Mine is set to departure time 615 or 630 (something like that) so that it finishes charging relatively close to my real departure time and battery should be warmer vs charging at 7pm and finishing at <11pm.
 

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If I use delayed charging based on a 6:00 am departure time and my fully depleted battery can be recharged in 4 hours using L2 charging, charging will start ~ 2:00 am so it is completed by 6:00 am.

If my electric company’s "off-peak" rates begin at midnight (or earlier) and end after my departure time, do I get any benefit at all from using delayed charging based on rate/departure times instead of just delayed charging based on departure time? Will charging still begin ~ 2 am (illustrations in the owners manuals seem to suggest it will)?

I would think the computer estimates the initial delayed start time so that full charge will be available at the programmed 6:00 am departure time. Start times are likely programmed to allow for unexpected circumstances (e.g., line voltage fluctuations), so it is possible my full charge could be reached at, say, 5:30 am. What happens if I use some of that charge to precondition at, say, 5:40 am, and my programmed departure time remains at 6 am? The computer may now calculate it needs to (and does) start recharging at, say, 5:50 for full charge to be reached by 6 am, so it doesn’t draw power from the wall during the preconditioning.

Is it possible your car was fully charged ahead of your programmed departure time, and the first preconditioning episode did not draw power from the wall because as the power for the preconditioning was being drawn from the battery, there was still more than enough time before the programmed departure time for any needed recharging to be done to replace what was being used, and thus the car didn’t immediately start drawing from the wall as the preconditioning was happening?
 

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Here is my take on what is happening. You say you have departure set at 7:30. First precondition is set for 6:45. Obviously it will use battery for this initially since it is at 100% charged. It "knows" that after preconditioning for 10 minutes it still has 35 minutes to recharge from the grid back to 100%. So when the second precondioning starts at 7:10, it "knows" it can't recoup that charge before 7;30 and thus draws grid power. Try setting the departure time to 7:00 with the first precondition at 6:45 and see, i would guess it will draw grid power.
 

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Discussion Starter #18
Just following up...temperatures have not been above ERDTT limits in 3 days now, and it doesn't look like they will climb above it for at least a few more, so I haven't been able to experiment much.

The car has been set to "Charge Immediately" for a few days now.

However, I noticed the last 2 days that even ERDTT precondition is not using grid power either - the engine starts, charging (if it was charging) stops, and if the car was full it doesn't *start* charging again either until . Since even on an ERDTT precondition the electric grid heat comes into play, it's also resulting in the battery being depleted in addition to ICE heat.

This morning it was -19 when I preconditioned the first time at 6:45. ICE started, zero grid usage - dash charge indicator is dark. At it's completion at 6:55 the car started drawing grid and charging again, but OnStar app showed 9% battery depletion. Seemed to be slow to recover, precondition second time at 7:10AM..wife left at 7:15, battery was still not 100%.

Anyhow....all things aside...we bought a second Gen1 Volt today. :)
 

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So what was the % when she left at 7:15, because you noted you have the "departure time" as 7:30. Although it would probably only charge 5% in those 15 minutes, if it was at near 95% at 7:15, that is what would be expected.
I am in Arizona, so I have no idea how ERDTT works.
 

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Discussion Starter #20
So what was the % when she left at 7:15, because you noted you have the "departure time" as 7:30. .
It had got back to 94% of something like that - the second ERDTT precondition didn't seem to *consume* any more battery, but it seemed to halt charging again.

FWIW, the departure time settings shouldn't matter at this point as the car was set for "charge immediately", not time or rate based. When the ERDTT precondition finished the car *did* start charging again immediately.

It's definitely strange behaviour, but like I said, I suspect most people don't see & follow the numbers like I do and don't even realize what's happening.
 
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