Odd behavior today

[diamondlarry]

I had some very weird things going on for the trip home from work today. It was 21F and the car had sat about 9 hours. The first thing I noticed was the OBDII C&C was displaying the F indicating the fan was on; I heard it running. Next, I was getting a 10-12 amp charge (when it wasn't fluctuating) into the pack (wasn't showing on the FCD) despite a SOC of 89.5% when I stated out (I grid charged with the key on the night before). I saw the pack voltage rise as high as 180V and SOC was up to about 97% at one point. The 12V was fluctuating wildly between 14.4V and as low as .6V. When the engine was running while in auto-stop, the 12V was steady at 14.4 and the "F" went out. I tried keying off the ignition a few times and even unplugged the OBDII C&C and plugged it back in with no change in the fluctuations. On the way home, I stopped at the post office and when I started out for home, everything was back to normal.

[Insight for life]

Ground straps?

[diamondlarry]

Originally Posted by Insight for life

Ground straps?

That was my first thought so I looked under the hood when I stopped at the post office and I didn't see any obvious problems.

[Eli]

The only thing that sounds terribly abnormal is the 12V battery voltage.

The other behavior is standard cold battery stuff, though I've never seen the SoC get quite that high, but the grid charge could explain that.

You may have experienced the BCM cold weather bug if you're running an 010?? The BCM in general seems very insistent on charging the battery when it's cold; I've noticed this with an 030 BCM.

[diamondlarry]

Originally Posted by Eli

The only thing that sounds terribly abnormal is the 12V battery voltage.

The other behavior is standard cold battery stuff, though I've never seen the SoC get quite that high, but the grid charge could explain that.

You may have experienced the BCM cold weather bug if you're running an 010?? The BCM in general seems very insistent on charging the battery when it's cold; I've noticed this with an 030 BCM.

I had the 010 in earlier this summer but I put the original (the one in the car when I bought it) back in. I like the original a little better because when I set the SOC high with the OBDII C&C it goes to 20 bars/81% vs the 19 bars/76%. The advantage I have is that when I grid charge to 100%, I can get the 2A background discharge down to 76%, reset the SOC high, and get the 2A discharge back again.

The same behavior happened again on the way home tonight. I forgot to mention that along with the 12V fluctuating wildly, the charge/discharge current would occasionally make some wild swings as well. I know it couldn't have been accurate as I saw charge currents in the thousands of amps. The SOC level was also occasionally showing values over 100% as well. Unlike yesterday, about 2 miles from home (9 miles from work), the charge behavior went back to normal and was giving the usual 2A discharge and a steady SOC level however, the fan was still on as long as the engine was running.

[Eli]

Interesting perspective - I like the earlier BCM revisions secifically because the recal point is 75%.. It annoys me when the newer ones recal to 81% and you're forced to let the battery discharge like that!

What would be better is to find a way to control where the DC-DC pulls current from. The car does it, so there must be a way.

The anomalous SoC and amperage readings pop up from time to time; CRC error detection will be added to V0.05 of the software. I wouldn't pay attention to the blips, just the steady readings.

The fan being on when the battery is below 32F is normal...

I would continue to watch things, but overall it sounds like more IMA behavior to add to your mental book.. lol.

[diamondlarry]

Originally Posted by Eli

Interesting perspective - I like the earlier BCM revisions secifically because the recal point is 75%.. It annoys me when the newer ones recal to 81% and you're forced to let the battery discharge like that!

What would be better is to find a way to control where the DC-DC pulls current from. The car does it, so there must be a way.

The anomalous SoC and amperage readings pop up from time to time; CRC error detection will be added to V0.05 of the software. I wouldn't pay attention to the blips, just the steady readings.

The fan being on when the battery is below 32F is normal...

I would continue to watch things, but overall it sounds like more IMA behavior to add to your mental book.. lol.

LOL! I may have to do some more experimenting with putting my 010 back in. The biggest reason I pulled out the 010 was when I would take road trips to Columbus, OH to visit my daughter. I would set the SOC high to get the background assist then, to keep the voltage from sagging too much, I would set the SOC to medium just before exit ramps and take advantage of the regen then reset to high again. One of my main reasons for buying the OBDII C&C was to be able to avoid the background charging that kicks in when the SOC drops to 18 bars and the 010 would only give me 1 more bar on a SOC reset. As far as the DC-DC sourcing, perhaps we could put a little bug in Peter's ear?

I wasn't too concerned with the anomalous readings especially since I know it's impossible for the IMA to be able to put out 6000+A.

I did not know that about the 32F threshold for the fan. This is the first time I've driven the car in temps this low since I've had the OBDII C&C. I have a timer for my grid charger set to come on a few hours before I leave in the mornings to warm up the battery which would explain why I didn't get the weird behavior yesterday morning when it was down to 7F.

[eq1]

I just had some odd ... battery management behavior similar to at least one aspect of your experience, plus I too just finished a grid charge, to 100% SoC.

Normally I'll get a background charge of about 5-10 amps when the HV battery drops below a nominal 65% SoC, until SoC is brought back up to a nominal 70.1%. Today, having taken just one trip after a grid charge, parking while in store, and then leaving for another trip, I got a background charge - which is most unusual since we know the pack is full.

I had reset my SoC from 100% to 75% when I first left home after the grid charge. I drove and brought it down to 70.1%, then parked at store. Left store and got the background charge. Never seen that before, ever.

I have to believe it has to do with the grid charge/SoC being abnormally high; possibly because of cold weather, as it has been colder than normal today, about 35-40F, yet the battery itself was 87F - so I doubt it, unless the cold weather thing is based on the ambient temp sensor, which seems unlikely...

One thing I'm certain of now, though, is that the BCM must have some more complex algorithms or heuristics (or something) to determine battery SoC, more complicated, that is, than just set thresholds for pack voltage, subpack voltage, and/or amps counting - something more like programmed known values, value changes, under various loads.

For instance, the BCM seemed to 'know' that the pack was charged above 75% even though I reset SoC to 75%, as when I hit the 72% positive recal threshold it almost immediately recal-ed to 75%. Pack voltage was not abnormally high at rest and under regen - though the change in pack voltage might have been... different, perhaps faster, under regen. My calculations have the car wiping out 5% state of charge/capacity - even though OBDIIC&C SoC readings during these two trips went from about 75% to 70% and back to 75% - so no net change in the nominal SoC...

In other words, the car is trying to bring the battery state of charge down, so it must have some way to tell that the battery is charged too much for reasons other than the nominal state of charge alone (which I reset to 75%), a pack resting voltage target alone, perhaps a pack single voltage target under a single load alone, or amps counting alone...

What does this have to do with the odd behavior? Not sure, but after 11,000 miles and experiencing the background charge at this juncture only once, after my grid charge, says it's not likely coincidence... One other thing to note: I was getting 0.1 and 0.2 amp charges and discharges toward the end of my trips, at seemingly regular intervals (i.e. not just DC-DC related fluctuations)... It looks like fishing behavior, like the BCM or whatever is fishing for some understanding of where the battery's at....

[biododge1]

eq1 what bcm do you have? your last sentance." It looks like fishing behavior, like the BCM or whatever is fishing for some understanding of where the battery's at.... " seems to follow suit on my hunch what the "newer" bcm does vs my old one

[eq1]

BCM is an 010...