Automatic B-mode at 84% SOC

[JimboK]

Originally Posted by ken1784

When I saw 82.5% SOC, the battery temperature was 50C and I could not activate the EV switch.

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

[TheForce]

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.

[rusty houndog]

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.

[JimboK]

Originally Posted by rusty houndog

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?

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.

[FireEngineer]

The battery ECU monitors battery modules in pairs for voltage.

Wayne

[ken1784]

Originally Posted by JimboK

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.

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

Ken@Japan

[JimboK]

Originally Posted by ken1784

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

Ken@Japan

I humbly stand corrected, thanks.

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.

[The Tramp]

Originally Posted by efusco

Just wondering if Ken in Japan or anyone else with advanced monitoring stuff has noted this before.

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

[efusco]

Sorry Tramp, but I don't know what "A + MAX" means?

[The Tramp]

Originally Posted by efusco

Sorry Tramp, but I don't know what "A + MAX" means?