OBD II Data for HVB

[rbort]

At the Natick Mall charging in the garage, my car has been charging since 12:10 PM almost 3 hours now. The charge level is at 97%, and the temperature on the high voltage battery is 95°. The temperature in the garage is 76 degrees.

120v charging showing lower temps, I have a request into Tom to check the cavity temp vs the HVB battery temp through SG to see how closely they mimic each other.  He's got a Cmax as I realize the Fusion is not the same.

-=>Raja.

Edited July 2, 2015 at 08:16 PM by rbort

[rbort]

Recharged the HVB back up to 85% tonight in 2 hours and 24 minutes.  Just unplugged it, will do the rest tomorrow before I leave to Boston.  Checked the temp one last time, 94F, the temperature in my garage is showing 76 degrees.  This pretty much gives enough data to show that 120v charging temps get up into the low to mid 90's.  240v charging for me has been at least 12 degrees higher.

 

-=>Raja.

[Hybridbear]

Recharged the HVB back up to 85% tonight in 2 hours and 24 minutes.  Just unplugged it, will do the rest tomorrow before I leave to Boston.  Checked the temp one last time, 94F, the temperature in my garage is showing 76 degrees.  This pretty much gives enough data to show that 120v charging temps get up into the low to mid 90's.  240v charging for me has been at least 12 degrees higher.

 

-=>Raja.

What temp are you checking?

[rbort]

Hey Bear,

 

On the Cmax there is a plastic cover behind the rear right hand side seat (put the seat down to access) that is a hatch to open and access the HVB disconnect contacts.  If you open that hatch there is a slew of hot air circulating around there while charging the car.  In that cavity also there is a metal plate and I am checking temps to the left of that plate where the air seems to be the hottest.

 

The IR gun is not making direct contact with the battery cells, but its in there contacting the circulating air which should have a direct relevance to the HVB temp.  I need to verify how close those match with Tom, he is going to check for me this coming weekend.

 

I don't know if you have the same thing with the fusion, if so you could open the hatch for the HVB disconnect and see if you find hot air circulating in there while the battery is charging.  If so check temp and compare to SG HVB temp and see how it relates.

 

-=>Raja.

Edited July 3, 2015 at 02:15 PM by rbort

[Automate]

The battery is about 97% efficient when charging.  Only 3% of the energy is wasted as heat. 

 

Maybe on average but the actual conditions do make a difference.  The majority of the battery heating is cause by the current flowing into the battery.  This heating follows the formula:

Watts = Amps squared * Resistance

So assuming the battery resistance stays constant, if the charging current is doubled the amount of heat generated goes up by a factor or 4.  It's not linear.

 

In addition the internal battery resistance does not stay constant.  Most materials increase their resistance as they are heated.  So as the battery gets hotter its internal resistance increases and the power loss, and therefore amount of battery heating increases slightly. 

Edited July 3, 2015 at 04:59 PM by Automate

[rbort]

And in the case where the charge current is tripled (240v vs 120v), then the heat factor goes up by 9?

 

-=>Raja.

[Automate]

And in the case where the charge current is tripled (240v vs 120v), then the heat factor goes up by 9?

 

-=>Raja.

Yes, if it's at full current, but doesn't the charger slow down the rate (current) as the battery gets close to full charge?

 

Also, as the battery temperature gets higher it will dissipate heat at a higher rate to the surrounding air.  For this reason you will NOT get 9 times the temperature rise.

[rbort]

Yes but only at the end once you are over 97% charge levels or there abouts.  Otherwise its a constant 3.3kw with 240v and closer to 1kw for 120v.

 

-=>Raja.

[rbort]

So Tom measured the internal cavity temperature this morning after he drove the car 2.6 kwh and recharged it.

 

He said that at half hour 45 minutes and one hour the high voltage battery temperature remains at 91 Fahrenheit the whole time. I'm not sure what to make of that, I would've expected some change.

 

He measured the internal Hvb disconnect hatch temperature and it went up to 107° then 109°. Maybe all this hot air was from the charger itself.

 

I would like more data from him but will have to see if he can get another test done. Just wanted to report his feedback.

 

-=>Raja.

Edited July 3, 2015 at 07:24 PM by rbort

[Hybridbear]

Today we did a 300 mile round trip. The ambient temp was in the low 90s this afternoon in southwestern MN. The HVB started out this morning at 84.2 and cooled to 80.6 on our drive westbound because the car ran the HVB fans the entire way. Leaving to come home this afternoon, the HVB temp had risen to 84.2 from being parked in the sun. The temp inside the car was very hot even though we had remote started it to start cooling it down. The car ran the HVB fans from the start and warmed the HVB while we were in hybrid mode on the highway. The car turned off the HVB fans once the HVB temp reached 100.4 F. The car showed the inside temp was about 77.0 F on the drive home, AC set on auto at 71. The HVB inlet temp was 99.8 F for the duration of our trip home. The HVB temp continued rising once the fans shut off. It peaked at 107.6 F which prompted the fans to turn on again. They ran the rest of the trip home and lowered the HVB temp to 105.8 F. We arrived home with about 1.100 showing for the ETE. The car did not charge immediately upon being plugged in. Right now I set it to charge now and I'll put it back to value charge after it charges for about 30 mins.

Edited July 5, 2015 at 11:10 PM by Hybridbear

[rbort]

So what does that ^^^ say?

 

AC didn't help at all for one thing that I can determine temp of the HVB went up anyways on the way home.

 

The cooled part on the way out, I don't know.  Why would the car run the fans to cool the HVB temp at 84 and shut them off at 100F?

 

Sounds like its hard to make heads or tails out of this...

 

-=>Raja.

[openair]

So what does that ^^^ say?

 

AC didn't help at all for one thing that I can determine temp of the HVB went up anyways on the way home.

 

The cooled part on the way out, I don't know. Why would the car run the fans to cool the HVB temp at 84 and shut them off at 100F?

 

Sounds like its hard to make heads or tails out of this...

 

-=>Raja.

Maybe state of charge is also a factor. The trip out, with a high state of charge it cooled the battery to ensure it would be able to deliver the full 4 bars without causing too much a spike in heat.

 

The trip home, in "hybrid," it warmed the battery to counter the low soc and because it was limited to the 2 bars that are available in hybrid anyway.

[Hybridbear]

Overnight the HVB temp cooled down to 84.2 F while being fully charged. The ambient temp was about 80 F.

 

Sounds like its hard to make heads or tails out of this...

I agree. It's interesting to document the behavior, though. Perhaps over more time a pattern will appear.

[Hybridbear]

Today the temp fell during the day and so did the HVB temp. It was down to 76 F when leaving work this afternoon. The fan came on to cool the HVB when I turned on the car & stayed on after I got home and plugged the car in. The ambient temp is now around 70.

[Hybridbear]

I have recorded ETE (Energy to Empty) of the HVB each morning for the past two years.  The following chart shows ETE (normalized to 100% SOC) vs. temperature.  The blue markers are from last year.  The red markers are for this year.  You can see the the energy capacity of the HVB has decreased about 0.2 kWh from last year.  The car is just over 2 years old with 25,000 miles.  I don't have any data for the first year I owned the car, but I would have expected the capacity to be around 7.2 kWh that year.  The total degradation is then approximately (7.2 - 6.9)/7.2 = 4%. 

 

 

 

The car will not allow regen when the HVB is above 98.4% SOC. As you have seen this degradation do you still not have regen when fully charged? Or do you now always have regen right away since the HVB doesn't get quite as full?

[larryh]

Regen is allowed only when the HVB SOC is below 98.5% SOC.  Above that, the max charge limit is zero.  HVB degradation does not change this.  The SOC of the HVB is a function of HVB voltage (post 148).  With HVB degradation, a voltage of 344.4 still corresponds to 100% SOC.  The car will still charge up to 100% SOC (if you charge the HVB while the car is running).  ETE is just lower at a given SOC/voltage when the HVB is degraded.

[Hybridbear]

This is an image of the trunk with the foam insert containing the charger and the tire pump removed. You can see a long black tube that runs the length of the trunk in the middle. There is a shorter black tube immediately to the left. There are fans at the top of each of the tubes.

 

The long tube draws in air from the outside or from the trunk, depending on whether the inlet door is open or closed, and circulates the air through the HVB. The motor controlling the inlet door is at the bottom of the tube. There are holes on the bottom left side of the tube so that it can draw in air from the trunk. If the inlet door is open, those holes are blocked and the car draws in air from the outside through a vent right below the bottom of the tube. If the inlet door is closed, the vent to the outside is closed and the fans draws in air from the trunk through the holes on the bottom left side of the tube. I have only observed the inlet door to be fully open or fully closed and not in an intermediate state in which it draws air from both the trunk and outside.

 

The short tube draws in air from the car's cabin and blows it out through the large opening at the bottom of the tube into the trunk.

 

What I have observed so far while the car is waiting to charge using value charge is that the car draws in air from the trunk via the longer tube and circulates that air through the HVB. The inlet door is closed. The fan in the short tube that draws in interior air from the cabin is off. So it appears to be circulating warm air in the trunk through the HVB.

 

When charging, I observe that the inlet door is open and the car is circulating outside air through the HVB via the long tube. The fan that draws in air from the car's interior may be on or off.

 

When the car was running this morning, it was circulating outside air through the HVB via the long tube. In addition, the fan in the short tube that draws in interior air from the cabin was on, drawing cabin air into the trunk.

 

ForScan seems to show the speed of both of the fans. The BECM provides the fan speed of the fan for the short tube that draws in air from the car's cabin and a count to indicate whether the inlet door is open or closed. The SOBDM provides the fan speed of the fan for the long tube that draws in outside air or air from the trunk.

 

 

 

 

This is what I see in Torque with the car charging. FORScan says the door is open. So the door count will show about 1880 when open & about 2236 when closed in Torque?

[larryh]

This is what I see in Torque with the car charging. FORScan says the door is open. So the door count will show about 1880 when open & about 2236 when closed in Torque?

 

 

Yes.  Open is 1880 and closed is 2236.

[Hybridbear]

Yes.  Open is 1880 and closed is 2236.

Is there any reason to display the PIDs that show the 1880 & 2236 values?

[Hybridbear]

Today I charged the Energi at the public charging station across he street from home for a little bit because we needed to charge both cars at the same time. Most of the time while the car was charging I sat in it with the AC running & the car on because I was reorganizing my displays in Torque. The SOBDM fan ran at 2750 RPM and pulled in hot air from outside. The HVB temp was 94 when I started charging. The outside temp was about 92 F according to the car displays. The HVB inlet air was about 100-104 F. The HVB temp rose from 92 to 98 while the fan was blowing hot air across the HVB while charging.

 

When the car is on the BECM fan will run when the DCDC a converter reaches 176 F to cool it down. With the car on & charging the car would let the DCDC a converter get up to about 195 F before turning on the fan to cool it down. It would only drop the DCDC converter temp down to about 180 F and then the BECM fan would turn off.

[larryh]

Is there any reason to display the PIDs that show the 1880 & 2236 values?

Those values vary only slightly from one day to the next.  Mine are 2224 and 1881.

Edited July 18, 2015 at 10:31 AM by larryh

[Hybridbear]

Those values vary only slightly from one day to the next.  Mine are 2224 and 1881.

Thanks. The one that shows the door status also varied slightly over time. When I took the pic it said 1883, after more time charging it slowly dropped, down to 1876.

[larryh]

AC did not appear to help much today with cooling the HVB during my 60 mile commute.  The outside temperature was 89 F.  When I first started out, I drove without AC for the first 20 miles.  The reported inside car temperature was between 93 F and 95 F (I'm not sure where that sensor is located).  The temperature of the air used to cool the HVB was the same. 

 

I then turned on the AC for almost an hour set to 78 F.  AC consumed 3.5 kW initially (for a short time) and quickly dropped down to about 1 kW for the remainder of the trip.  The reported inside car temperature fell to 88 F.  The temperature of the air cooling the HVB fell to 91 F.  So the temperature of the air used to cool the HVB was only about 4 F degrees cooler with the AC running.  That's not going to help much.  The HVB fan was running at around 2,500 rpm drawing in the air from the cabin to cool the HVB.  The temperature of the HVB reached 102 F. 

 

The HVB fan did not run while the AC was off and it did not start until the AC had been running for a while and the HVB temperature reached 97 F.   The temperature when I started the commute was 90 F. 

Edited July 27, 2015 at 12:14 AM by larryh

[rbort]

^^^  :)

 

-=>Raja.

[Hybridbear]

I have recorded the HVB voltage variation in millivolts (mV) for a few trips. The HVB voltage variation seems to very closely mirror the HVB power in kW. The more power drawn from the HVB, more mV of cell voltage variation.

 

Here is a chart: