Automatic B-mode at 84% SOC

Interesting. Maybe the fact that my battery temperature was a little lower than that (47C/116F) made a difference.

 

I have this "B-mode" recorded from my can-view. As soon as I get back from my Hymotion battery install I will extract the data and post the results. I got this B-mode a few times coming down the mountains today. I'm sure I will get it a few more times on the way back home. This B-mode started when SOC reached about %80-%81 according to the can-view. I dont think I got the SOC any higher than %82.

 

As to the heat in the battery, the battery is a heater both charging and discharging. Any "excessive" heating would be caused by inadequate cooling control or by battery cooling design flaws. It would appear, from the low numbers of destroyed batteries reported, that battery temperatures reported so far are "normal" for the system.

Even EV mode recognizes those numbers as possible and has strategies in program.

So far I have no idea what monitoring takes place of the cells in the battery but gross temperature of the "battery" is probably only one thing being noted by the system and until we have a breakdown of the code there is no way of knowing for sure what the machine is actually doing about instantaneous inputs. Is it the battery temperature being measured or the temperature of the air flow around the battery? From what does the temperature signal come?

Does the system monitor individual cell condition? Cell bank condition?

Insufficient data and insufficient error report to be concerned.

 

The CAN data stream includes, at a minimum, the temperatures of the hottest and coolest cells, indicating that the temperature of each cell is monitored.

It also monitors overall pack voltage, which it presumably uses at least in part to figure SOC. I don't know whether it monitors voltages of individual modules or cells, though my (mostly uneducated) hunch is that it probably does.

 

The battery ECU monitors battery modules in pairs for voltage.

Wayne

 

There are only three battery temperature sensors, therefore it is impossible to monitor each cell's temperature.

Ken@Japan

 

I humbly stand corrected, thanks. :embarassed: :sorry:

As I researched this today, I reread this, verifying (on page 7) your statement. I wasn't second-guessing you, BTW. I regard you as among the most credible and knowledgeable of experts on PriusChat. I just wanted to reconcile discrepancies between this, statements of others, and my own understanding.

Here’s what led me to make my statement. The temperature that CAN-View reports is described on the CV web site as "the temperature of the hottest battery cell." I inferred from that that all cells are monitored, otherwise the hottest couldn’t be determined. The CV serial data output includes values for “minimum” and “maximum” battery temperatures. My mistaken understanding was that these too were cell temperatures. That understanding came from a flawed recollection of this site that describes the CAN decoder application I use with CV. The site actually describes the temperatures as module temperatures, but that too obviously is wrong.

 

Yes, every time the A + MAX goes below 10.

 

I thought I read somewhere that the Prius battery does not benefit from being at 100% SOC and tries to put it in the SOC sweet spot for long battery life.

 

Here is the section of data relating to the b-mode. Its in xcel format if anyone wants to graph things out. B-mode is entered when SOC is greater than %80.

http://stuff.jaygroh.com/priuschat/priusdata/bmode.xls

 

Guys,
I've got a mountain commute and I've noticed that I rarely get full bars. I regularly get into the first green bar, but the last one rarely turns green. Don't have a CV so I don't know the precise SOC. I switch between B and D depending on the grade. There are a few pretty steep parts (8-10% grades) where I use B and for the rest it's pretty much D. OAT usually ranges from around 65 deg F to 90 deg F on this commute. Today I think it was in the 60's all the way down the canyon.

I have EV mode, but it seems to have malfunctioned because it hasn't worked in months (I've got the coastal tech mod). Any ideas?

 

Yesterday I came back home passing the Stelvio Pass: I managed to drain TOTALLY the battery: It will not go under 29% and only then the system would refuse to accelerate the car from a hairpin turn.

I got to the top that SOC was reading 32%, and temperature was 115 F.

Just for curiosity, mileage was reading 30.1 MPG at the top.

Coming down, when the battery reached 70% the temperature reached 130 F and the system was not accepting an input charge anymore.