Low SOC after sitting a few days - GreenHybrid - Hybrid Cars


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Old 09-15-2016, 05:26 PM
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Default Low SOC after sitting a few days

So now that I got the FEH back from the wife, AC seems to be fixed, I notice once in a while, usually after it sits in the garage for the weekend that when starting up the SOC is like 28-32%, and it was in the 50's when parked.
Nothing is plugged in or left on.
I only drive ~6mi to work, or 12-15min, and it's defiantly in 'recovery' mode the whole way to work, usually get to go EV the last 1/2mi or so, at ~SOC45. Re-gen is not working (ie put in L to 'charge' coming to a stop sign/light) I get no resistance, and the RPM goes up, over 2-3K

08, only 93K miles

Ideas?
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Old 09-16-2016, 08:08 PM
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Default Re: Low SOC after sitting a few days

Mine does this occasionally as well. I don't know what the actual SoC is when it happens because my wife usually drives it and tells me about it later so I don't ever get a chance to plug in my OBD reader and get the SoC from it. But, I do know that it gets down to 1 bar on the hybrid screen and it definitely goes into a recovery mode like you said. I have not figured out any pattern to it. We can park it with 5 bars and then the next morning it'll be down to 1 bar. It happens about once every 1-2 months or so and there are no trouble codes stored in the computer. I'd say this has happened at least a dozen times now...maybe 2 dozen even.

I might be willing to consider it being a battery calibration event, but we've had it happen two nights in a row before so that would be odd. Unrelated, but I have only experience one battery calibration where the SoC goes really...like nearly 100%. The vehicle absolutely refused to shut off the ICE, but once it got the SoC all the way up it started behaving normally again.

We have a 2012 with 90k miles.

Last edited by bdginmo; 09-16-2016 at 08:10 PM.
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Old 09-17-2016, 04:25 AM
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Default Re: Low SOC after sitting a few days

I'd chalk it up to calibration, if it didn't happen almost every weekend for the last few weeks.

I haven;t seen a calibration in a longtime; but again wife's pretty much stolen the FEH for the last few years.

I'd kinda like to force a battery calibration to see what happens. Maybe a bad cell? How is the software programmed to handle those if it finds one?
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Old 09-17-2016, 02:20 PM
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Default Re: Low SOC after sitting a few days

I agree. I don't think it's a calibration either, but I'm unsure of what it could be. Like I said, no trouble codes so I have to assume that the computer doesn't think it's a bad enough problem to trip the CEL. If I can figure out a pattern I'll post back to this thread.
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Old 09-18-2016, 07:24 AM
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Default Re: Low SOC after sitting a few days

IDK either; so this 'weekend' I parked fri about 5pmish, 53SOC. Didn't touch it Sat; Sun morning at 9am it went to 30SOC.

Out of curiosity (since I had the extra time today) I pushed the HV jump-start button... ~5min or so later, light goes out, turn on SG, SOC still at exactly 30.0

It still starts when I have the low SOC. I have nothing plugged into the 12V outlets, no lights on; but I believe those all power from the 12V batt once the key is removed.

so a 20% SOC drop in ~36hrs ???
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Old 09-18-2016, 11:33 AM
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Default Re: Low SOC after sitting a few days

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Originally Posted by 08hybridok View Post
so a 20% SOC drop in ~36hrs ???
Try this, repeat your experiment but open the HV switch on top of the battery housing after you park. Then after 36hrs, close the HV switch and check SoC. That should determine if the SoC loss is internal to the battery or if something external is drawing current.

My guess is that SoC is estimated from battery voltage, that's why calibration is necessary. So if a battery cell was failing and no longer holding it's voltage, that would look like a reduction in SoC.
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Old 09-19-2016, 08:47 AM
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Default Re: Low SOC after sitting a few days

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Originally Posted by econoline View Post
Try this, repeat your experiment but open the HV switch on top of the battery housing after you park. Then after 36hrs, close the HV switch and check SoC. That should determine if the SoC loss is internal to the battery or if something external is drawing current.

My guess is that SoC is estimated from battery voltage, that's why calibration is necessary. So if a battery cell was failing and no longer holding it's voltage, that would look like a reduction in SoC.
OK so I didn't have to go to work afterall yesterday, so it sat another 24 hours.
Go out today and it's still at exactly 30.0
Still started, but of course was in weird mode all the way to work, no Regen brakes, no charge when using L, very little assist, the needle was almost always in the charge side while cruising.
Got up to like 45soc by the time I got to work and got to EV in the parking lot, still using L it reved the engine vs charging the batt...
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Old 09-19-2016, 09:08 AM
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Default Re: Low SOC after sitting a few days

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Originally Posted by 08hybridok View Post
OK so I didn't have to go to work afterall yesterday, so it sat another 24 hours.
Go out today and it's still at exactly 30.0
I don't understand. Did SoC drop by 20% in 24 hours with the HV switch opened?
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Old 09-19-2016, 10:26 AM
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Default Re: Low SOC after sitting a few days

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Originally Posted by econoline View Post
I don't understand. Did SoC drop by 20% in 24 hours with the HV switch opened?
No I left the switch alone, so in the first 36ish hours it dropped 53 - 30, the following 24hrs it stayed flat at 30
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Old 09-22-2016, 06:44 PM
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Default Re: Low SOC after sitting a few days

It doesn't happen often enough for me to do any experiments like turning off the switch to the HVB.

The interesting part is the fact that it dropped 20+% and then stopped dropping. Although I haven't collected actual SoC values I can say that this may be the same behavior I'm seeing as well. It never drops enough to fully drain the HVB. Is that a clue? Is the computer sensing a problem and activating a disconnect or relay to prevent damage to the HVB? Of course, if that were the case I would expect the CEL to come on and a trouble code to be stored.
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