[DRIVING] VW Touran powered by Nissan Leaf [FINISHED]

[johu]

First road trip with the new pack today. I drove about 250 km in one piece with 150 Wh/km. Hypermiling with 100 km/h. Started with 95% and arrived at the charger with 27%.
Unfortunately had a VCU reboot after 100 km. Finally caught the flag: IWDG - watchdog reset. Hmm

Charging was pretty smooth and started at 80 kW. I think I can optimize power some more, it throttled too early. But then it was me who throttled. As I never trust my own wiring-foo I stuck my hand into the HV loom and noticed the B- cable got uncomfortably warm up to the point where it started emitting smells. So dialed back charge power to 15 kW. Cable quickly cooled down and I went back up to 130A/50 kW. That went well enough to finish the session. The inconvenient consequence: I have to drop the lower 4 battery modules and redo the bolt of the upper 4 modules.

Apart from that the modules gained 10°C of temperature during the 250 km drive (8 to 18°C). They heated up pretty equally to 35°C during charging and then cooled back down to 33°C over the remaining 100 km. Outside temp was 10-14°C. So I think for moderate trips this should work well.

[johu]

Back from the trip and have some data to share.
I drove the car lightly to the first charge stop and also topped up 9 kWh while visiting Udo (that 3.3 kW OBC is really inappropriate now). I started in the morning with 13°C in the battery and arrived at the one and only quick charge stop with 22°C after 284 km. Again the battery reached 36°C from charging 15 kWh with about 60 kW average charge rate. I throttled it straight from the beginning as I had to leave the car alone to take care of my own business.

The temperature then dropped to 34°C while b-road driving. Then on A49 I drove a bit more spirited with 140 kph cruise control and ended up back home with 40°C in the battery. So 110 kph it is for long range driving until I improve battery cooling.

Temperature is spread evenly across the modules, the warmest one was 41°C and the coldest one 38°C.

I'm no longer 100% sure what it is that starts to smell during a quick charge session. It could also be my 50cm extension lead from the MG charge port. Will check that at some point for signs of over temperature. So maybe I don't need to drop the battery for just that. It seems impractical to charge at 100 kW anyway with a lack of battery cooling.

Next longer trip is to Augsburg via Frankfurt, 550 km. That probably needs 2 charge stops and will supply us with more data.

[arber333]

I drove a bit more spirited with 140 kph cruise control and ended up back home with 40°C in the battery.

Maybe you can install couple of the ATV fans to blow air across the assembly during charging AND driving? I noticed a lot of difference if i removed the battery box lid while driving. temperature actually wend down 6deg!
The reason to use those is they are waterproofed and resistant to outside use.
This is the fan i am thinking of using in my boxes. It draws about 0.6A at 14V.
https://www.aliexpress.com/item/3301573 ... 1802tPuJlT

This blowers would also be worth trying especially as you can more efficiently direct the airstream over modules...
https://www.aliexpress.com/item/3302106 ... ry_from%3A


I also have this one, but even though it blows quite good it draws 2.5A!!!
https://www.aliexpress.com/item/1005005 ... ry_from%3A

[midway]

I have such a fan installed inside the battery case.
https://aliexpress.ru/item/32797575257. ... 3931858497

[tom91]

Maybe getting some stick on temperature labels will be good for your testing It "logs" highest temps.

https://uk.rs-online.com/web/p/temperat ... ls/0285914

[arber333]

I have such a fan installed inside the battery case.
https://aliexpress.ru/item/32797575257. ... 3931858497

Nice find! I have like 3 separate module locations this would really make it easier to mount... thanks.

[johu]

Maybe getting some stick on temperature labels will be good for your testing

Good suggestion! Was thinking about some 1-wire sensors but this is even easier.

I have such a fan installed inside the battery case.

Nice unit.
Can it blow air out of the case? How do you make sure no water gets in?

[midway]

Good suggestion! Was thinking about some 1-wire sensors but this is even easier.


Nice unit.
Can it blow air out of the case? How do you make sure no water gets in?

I plan to route the air ducts under the hood or into the trunk

[bewo]

Hi juhu,

maybe I missed the information in this really huge thread. How did you deal with the two signals of the generator DFM and L? I know that L is used to activate high load devices like seat heating or the rear window heating.

[johu]

How did you deal with the two signals of the generator DFM and L

I wasn't even aware these existed. But rear window heating works and also power steering. Power steering just checks for motor rpm, that's why I simulate idle speed of 700 rpm. Maybe heated window does the same?

[johu]

Despite the replaced wifi module and despite giving the scheduler top priority the VCU restart happened again today. I almost have a hunch it happens after a fixed time now but that is very vague.

The reset cause is IWDG, so watchdog reset. There'd have to be some exception or endless loop to cause this...
If anyone wants to follow along: https://github.com/jsphuebner/stm32-car/tree/touran-meb

[johu]

Reboot problem solved: viewtopic.php?t=4925

[johu]

With the above established I want to return to the original questions and the (partly premature) conclusions.

So we start with a perfectly working car and a terminal class that remained largely unchanged for years. After fixing a completely unrelated problem with the battery the VCU starts to do spurious resets with the same software as before.

I then suspected the power supply of the VCU to be the issue as some cables got caught between battery and chassis and were shorted to ground. But never found any further evidence. I then scoped the supply rails of the VCU (3V3, 5V, 12V) only to find nothing spurious at all.

Meanwhile the software got a major overhaul to support the MEB BMS. The problem did not go away.

Then I swapped the ESP module for the new one and seemingly the problem was gone. In reality it only became rarer and I explain this with the poor wifi performance of the new module. It just didn't manage to refresh every 500 ms.

One thing I still don't quite understand is the behaviour of the ESP module. Normally, when the STM32 resets and the ESP does not this results in the ESP expecting 921k baud rate and the STM32 running at 115k. So the dashboard should stop updating in this case. But it keeps updating after the reset. This lead me to believe in the supply rail issue. Namely I thought the ESP got into some state where it briefly shorts out the 3V3 rail (it must dip below 2V for the STM32 to reset). But shorting out an 800mA LDO takes some grunt. So maybe the STM misbehaving led to the ESP resetting as well? Why?

Also the supply rail theory was contradicted by the watchdog flag being presented as a reset cause. I did a bench test were I simulated supply rail dips to find out whether this could falsely be detected a watchdog reset. But couldn't find proof for that.

Well the 500 km drive to Augsburg will show whether the problem has really gone away now. Anyway it was a good chance to harden the terminal.

[johu]

Yay, road trip reporting time Another 1000 km covered going to Augsburg and back.

Key takeaways

• The VCU restarts no longer occured
• CCS charging was absolutely flawless except one session getting interrupted when someone used the other outlet on the same charger. Could restart no problem
• Battery rapid-gated badly especially on the return trip

Drove the first leg (about 200km) to Frankfurt and while waiting for Janosch recharged the car to 90% (added 33 kWh in 45 mins). Then came Stau time and we were stationary for like 90 minutes total. Surprise: contrary to oily propaganda an EV does not discharge while stationary

Went for another charge stop about 200 km later and added 18 kWh in 20 mins before rapid-gate. Charged another 10 minutes before arrival because I wasn't sure of the accuracy of my SoC calculation and we thought it was a bad idea to test it at night and freezing temps

On the return trip I did a nice 28 kWh charge session in 30 minutes heating the battery from 18 to 40°C. After that it hardly cooled down because consumption was rather high. Rain, headwind, 3°C ambient and high-ish speed (120 kph) did not help. So the second charge session heated the battery to 50°C and completely ramped down charge rate to 0 already at 45% while I was eating a burger.

So instead of going straight home I had to insert another 5 minute stop once the battery had cooled down a bit.
I have also moved the derating point for the discharge current from 50°C to 52°C so the car is still somewhat drivable after overheating from charging.

More on the event that we intended will be published in the Events section

[johu]

Did some tests with different wheels:


On other news I've replaced the rear springs and front shocks and springs as well as the crusty hatch

[johu]

Not sure where this post fits best as it is kind of a road trip, EV improvement and CCS mix.

So, I went to Hamburg to meet Mathieu who has done various conversions like the Mustang and Toyota Land Cruiser. Plan was to get CCS up to speed on the latter and fix a few things on Touran.

I wanted to make it to Hamburg (300 km) on a single charge but 40 km before my destination and with 18% left I chickened out and plugged in for a few minutes. When I arrived the battery had time to rest and let the SoH estimation run: 100.5% That is with 155 Ah configured (158 Ah is spec). So the 18% were accurate and I could have made it on a single charge. Also I didn't start at 100% but 91%.

Anyway, I met Mathieu the same night, we updated firmware on his Foccci and went to Ionity which hadn't worked previously. Now it did:

Now he can use up the 1500 kWh that he won on the 2022 e-cannonball

The next day we fitted a pull-up resistor to 5V to the PP line and now Tesla also worked:

There was no lack of spectators, Tesla staff from the adjacent Tesla service center.

Then we changed the CAN mapping to use 9 bits for the current request to be able to charge at more then 255A which also worked:

We saw 300A briefly but the battery was too full.

On Touran I redid the extension cables from the CCS port, they are 50mm² all the way now.

Then I cut open the battery box a bit more to reach the upper battery pole bolt that I suspected wasn't tightened. We made a special T30 tool and I gave it a slight twist. It should be at around 10 Nm now which is spec for an M6 bolt.

Finally I fitted a fan that is supposed to flow air in through the inner two BMS cable holes and exit through the outer ones. I stuck some corrugated tube into the outer ones as an air guide. Indeed there is a small air flow when running the fan. To be tested.

On the way back I drove in heavy rain and encountered 3 accidents. With improved confidence I emptied the battery down to 9% or 3450 mV per cell. Perfect balance down there, just 3 mV delta, likewise at the top. So they are really well matched.

[johu]

Added a write up on Tourans nastiest faults to the wiki: https://openinverter.org/wiki/VW_Touran ... asty_stuff

[tom91]

Are you monitoring the charge port temperatures? As with a 4V drop at 220A you are losing nearly a Kw in heating, so best to figure out where its going.

[johu]

Sorry, missed that.
Yes I do monitor the temperature and it barely changes. The cable run is 2x2m @ 50mm² and 2x1m @ 35mm². And I'm not sure if the charger measures before or after its own roughly 4-5m charging cable. Then of course we have the bus bars themselves
The warmest one of them all is still the B- cable as per this video (18 to 44°C in 8 minutes @ 220A)

[johu]

Another road trip and more data.

First trip was to the seaside, 450 km one way. Temperature was 30°C and the battery heated up while waiting 4 hours for an accident site to be cleared. Unfortunately no charger at the resting area the we waited at. We charged after around 250 km on a 50 kW charger and even that managed to overheat the battery. So when we returned from our walk around the lake it was sitting at 70% and 10 kW. Anyway, enough to continue.

At our holiday house I was allowed to plug in the granny cable but was made to pay 40 ct/kWh. Still, convenient (and solar power).

On the return trip we charged at the same spot and the session got interrupted two times when someone new plugged in at the other port. A Clara issue that is now fixed. I became a but faint-hearted when only 25% was left, 50 km and Germanies steepest highway incline still to go. So we plugged in again for 10 minutes. When ascending said incline I forgot how hot the battery was and drove up rather spirited. That used up the 2°C leeway I give for discharging so the BMS cut out power completely just has I got on the exit. We got out of the way and waited 1 minute until we were given a 100A limit.

As a consequence I have now made the derating curve for temperature less steep. Derating starts at 43°C for charging and at 45°C for discharging. That increases the chance of hitting and equilibrium instead of switching back and forth between 100A and 0A.

On the hardware side I fitted a larger fan:

14000 rpm, 40W, 230m³/minute.

Then I had a chance to test the improvements on Monday and Tuesday, driving 400 km on each day.

Monday was pretty warm, between 25-28°C (cold for Gregski). The batteries had already heated to 33°C when I arrived at the first charge stop. I charged until the limit kicked in at 60% which was enough to reach my destination. Wow, not even one full charge session despite that new fan. I think the air flow design is suboptimal. I may have to add additional venting holes.

On the way back I got wise and charged before dropping below 30%. Below 30% I observed the batteries heat a lot faster from driving. It was a mild 19°C and even though I did hit the temp derating it took a lot longer before it happened.

Charge current is now limited to 185A which also eliminates the alarming smells. Driving was semi-spirited, 120 kph, sometimes quicker, sometimes slower. Consumption was 160 Wh/km on Monday and 170 Wh/km yesterday (rainy)

Still improvements possible, as always. We won't do the full September road trip in Touran but instead borrow my dads Seres which has proven to have sufficient battery cooling.

[uhi22]

The temperature increase while just moderate driving is surprising. Maybe there is still unintended resistance in the module connections (oxide, missing screw torque?).
For comparision, my also air-cooled Ioniq, which has a quite low temperature increase while highway driving in summer. The blower only started while fast charging.

[johu]

Well actually those plots sort of align. I add 10 °C by driving 250 km with a taller and heavier vehicle while you add 5°C by driving how many km? Also it looks like the Ioniq battery also collects most heat towards the end.

What's way better in your case is the cool down.

[uhi22]

It was around 120km in my case. I was hoping, that the way bigger battery has much less resistance, so that the heat produced with guessed 20kW highway cruising is negligible. Are there any data sheets available for the ID battery regarding the resistance and heat capacity? This would allow some simulation, and comparing with the measured data.

[johu]

We only have this: https://www.lgensol.com/assets/file/LGE ... s_2022.pdf (it's two E78 cells in parallel)

So 1.48 mOhm per cell, should be 0.74 mOhm per cell pair, times 96 71 mOhm. Driving at 20 kW would be about 60A. So 60²*0.071=255W power loss. That's where my knowledge ends, how do you calculate how much temperature that puts into the 256 kg of mass?

Charging at 185A would yield 2.4 kW of losses.

[modellfan]

So 1.48 mOhm per cell, should be 0.74 mOhm per cell pair, times 96 71 mOhm. Driving at 20 kW would be about 60A. So 60²*0.071=255W power loss. That's where my knowledge ends, how do you calculate how much temperature that puts into the 256 kg of mass?

255W * 256 kg * 0.90 J/g ° C for Aluminium gives you a temperature change rate °C / s

I put already some thoughts into it. What we basically need is a temperature prediction. It could even happen, that you DC-Charge very short, the energy loss didn't participate yet to the temperature sensors yet, you drive in a heavy load scenario and you highly overshoot the max temperature. The main topic is , that the time delay between battery current and temperature is quite high. There are two generic approaches. Maybe discuss it in another thread?

1 Build a full fledge simulink model, to simulate all heat flows. This will be realy time consuming, complex
2 Empiric aproach. Assume general influences and match measured values to a model
2A Do it with a neural network
2B Do it with an estimated equation.E.g. a PT1

2B would be my aproach to give a try. I would like to measure as much as possible driving scenarios and match them in Python offline on an equation to find out the paramaters. Then you can implement the equation incl. the parameters in the ECU. I assume following parameters are relevant: Charge/DIscharge kW für dissipated Energy; Driving Speed for underflow convection; Outside temeperature for convection; Temperature heater/cooler activated. Basically when you get a PT1 like equation you can run it with several max charge /discharge powers to find out the limit, to not overshoot the allowed max temeprature.