EV-CAN message Decoding

[garygid]

Is anybody else using CAN-Do to look at these "temperature" values in the on-line Logs?

If you have, what do you think?

 

[GregH]

Looking at 55A2, D3, and D6 in the 45-minute 35-mile driving log (on-line), D2 looks like it might be "battery temp", but D6 is essentially constant, and D3 has high-frequency components, but its average essentially matches D6.

Neither D3 nor D6 are increasing during the trip.

So, I am guessing D6 MIGHT be Charger Temp, D3 PERHAPS Inverter Temp, and D2 the "combined" Battery Temp.
But, still just guesses.

I started monitoring 55a while driving.. Yeah D3 jumps around a bit.. Maybe it is near some ambient air intake? It seemed to jump when the car starts moving then settle, although that might be my imagination.
D2 certainly seems to rise with activity then cool down moderately soon (probably too soon for something as large as a battery).. Perhaps this is motor or inverter temp?
D6 is a lot slower, maybe a better battery temp candidate.
D5,7 and 8 have been 5f, 5b and 08 every time I've looked in the last 24hrs.

 

[GregH]

Oh, and range for those 3..
D2 low 44 after sitting overnight, high 5c right after a good drive (although if I sit and watch, it cools down fairly quick.. One tick every 5-15sec)
D3 low 3f, high 4d sitting in a hot parking lot afte driving
D6 low 44 after sitting overnight, high 52 after the long drive

 

[Brightonuk]

I'm not suggesting this to somebody who has never worked on cars, or can't read a schematic, or has no experience in troubleshooting electronics, so "DON'T TRY THIS AT HOME".

Ok back to the horn upgrade for me

 

[garygid]

55A2 climbs while charging (over 6 hours) and during a 35 mile (45 minute) drive.

All three climb when doing the L2 (16A) charging.

The same cooling fluid passes through the inverter, motor,
and charger, when driving or when charging.

Durig my easy 35-minute drive, D3 has "noise" around a constant average,
and D6 was just flatlined (constant value).

 

[TonyWilliams]

Maybe I missed something.. but the BMS (or "LBC" as nissan calls it) handles the temperature sensors. The BMS is inside the pack so the temperature wires never come out. You'd have to open the pack to try to spoof temperature readings.

Ya, I see that around page 172-177 of the service manual (battery section). I'm still game, if it helps.

 

[GregH]

Ok, I take back what I said about D3.. It rises quickly with any hard acceleration or regen and falls quickly under low current.. So I'm guessing it's either the motor or inverter (whichever has less thermal mass and is in closer contact with the cooling system)

Also just took another look at the service manuals and see the 4 temp sensors in the pack connected to the LBC all internal...

Also noticed that from the QC port not only do you need to get past the QC relays to reach the battery but also the normal charge relays and of course the main pack contactors.. So basically 3 sets of relays between the QC port and battery... Ugh.

 

[garygid]

If D3 is the Inverter Temp (or possibly the motor, but the inverter should have less thermal mass), then its average would probably be the cooling fluid temperature. During my 35-mile drive during the cool of the morning, this "average" was essentially a constant temp, the same as D6. So, D6 might be the coolant temp, or the Charger temp.

During the 6-hour L2 charging log, all 3 temps essentially rise together, but D6 is a bit higher as I recall.

I need to re-plot the three temps in CAN-Do, and look at the fine detail. However, my guesses (for this MsgID 55A data) are now:

D2: Battery Pack
D3: Inverter
D6: Charger

I will try to post/show the charging and driving plots here.

 

[garygid]

Charging L2 at 16A in cool garage - 6 hours

Drive 45 minutes, about 60 ph, 35 miles

Maybe:
Red is Inverter?
Green is Motor?
Blue is Battery?

 

[GregH]

Very strange.. If blue/D6 is battery, why would it warm up so much on a measly 7-8A charge but barely during a drive? A drive outside in likely a warmer ambient than your garage I'm guessing.
As best I can tell there is no circulated air in the battery correct? If this is true, the battery would have immense thermal mass with no cooling other than ambient soaking. I'd expect the heat generated by charging would almost entirely be offset by the cooler overnight ambient temps in the garage whereas driving with moderate acceleration and regen over hot asphalt and baking in hot parking lots during the day would cause a slow but notable rise in battery temp that would linger for a long time due to the thermal mass.. It is possible that none of these are our battery temp.

 

[Stoaty]

Maybe:
Red is Inverter?
Green is Motor?
Blue is Battery?

One way to help determine whether a value is the battery is at the change-over point of the battery gauge on the Leaf Dash. We know that the transition between 5 and 6 bars is 75 degrees F. Assuming you have figured out how to convert the values to temperature, you can see which value is 75 degrees at the transition. I see this transition point a couple of times a week with current weather and car parked in San Fernando Valley during the day and cool parking garage at night.

 

[ElectricVehicle]

Very strange.. If blue/D6 is battery, why would it warm up so much on a measly 7-8A charge but barely during a drive? A drive outside in likely a warmer ambient than your garage I'm guessing.
As best I can tell there is no circulated air in the battery correct? If this is true, the battery would have immense thermal mass with no cooling other than ambient soaking. I'd expect the heat generated by charging would almost entirely be offset by the cooler overnight ambient temps in the garage whereas driving with moderate acceleration and regen over hot asphalt and baking in hot parking lots during the day would cause a slow but notable rise in battery temp that would linger for a long time due to the thermal mass.. It is possible that none of these are our battery temp.

Chemically charging for this battery may be exothermic - heat is released when charging from chemical reactions, while discharge may be neutral or endothermic, that is the chemical reaction is heat neutral or absorbs heat. On discharge, you'll get more heating due to the higher currents and resistive losses in the battery.

One thing that may help differentiate and identify the tempearture readings is to look at the temperatures at the end of charging as the charge current tapers down, the charger will dissipating less heat, while the battery will likely be producing more heat even though there is less energy going into it.

120 vs. 240V charging might reveal some things also - the heating of the charging circuits will probably be similar for the same current level, while the battery is getting twice the power so the battery will presumable get hotter on 240v charging vs 120V charging.

Another possibility for differentiation is to heat or cool the inverter casing, by a hair dryer, fan, portable air conditioner or ice pack - all with the appropriate precautions to avoid damage from hot, cold, water or condensation - ahh... better yet - Dry Ice for cooling! You might be able to external temperature manipulation to the motor also.

Could also try high power uphill vs high power downhill / regen - say 30 kW in both cases - the motor and inverter will probably have a similar temperature rise in both cases, while the battery may show a difference in temperature due to charge vs. discharge.

 

[garygid]

You can see why we need some more Testers and Loggers
to help untangle some of these values.

Next chance I get I will look through all the other values to see
if I can find other values that appear to be temperatures.

 

[Stoaty]

You can see why we need some more Testers and Loggers
to help untangle some of these values.

Installed OK under Win 7/64, but can't figure out how to open the CAN log test files. Any help appreciated.

 

[garygid]

Click the "I/O Control" button, then Browse,
select an ".evc" binary log file, and Read.

 

[TickTock]

Here's another datapoint just like Gary's. I plotted D2(red),D3(green),D5(blue),&D6(purple) with no scale (Y axis is from 50 to 150 integer).
During a 25min drive:

During a charge to 100%:

I am guessing:
D2 : battery (largest thermal inertia)
D3 : motor controller (correlates well with the motor during drive)
D5 : motor (only active during drive)
D6 : battery charger (only active during charge)

 

[TickTock]

I wanted to also mention that I think the scale factor is not a simple integer scalar (may not even be linear). The one in the recipe file indicates only 68-70F degrees on the battery although it was over 100F outside.

 

[TickTock]

I created an EV message definition spreadsheet to try to consolidate all the learnings into one place for reference. If I am missing any information or if anything is wrong/contested, please let me know and I will update.

evmsgs

 

[garygid]

Have you included everything from turbo2ltr's two spreadsheets?

Some of the value-conjectures from my "recipes" are not there.

But, Good Work!

 

[TickTock]

No. I wasn't aware of any previous compilations (why I decided to build my own). I just searched turbo2ltr's posts keyword spreadsheet and only found one on solar production. This forum makes it very hard for anyone coming late to a conversation to pick up prior knowledge - needs more sticky FAQ's IMO but I diverge... Anyway, I did go through the recipe list. I thought I only left out those entries that were redundant or labeled "old" but I see I did miss the #5min charging and two temperature theories - added now.