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The lexus UX300E has active air cooling whereby it circulates air across the modules and returns to air to water heat exchangers that I believe are plumbed into the vehicle AC lines and solenoid controlled. The pack is well sealed and so there is a reduced risk of external contamination or moisture.

Just thinking out loud here, but has anyone looked into a basic immersion cooling system? If the battery box does not contain the contractors or other electronics and is water tight, then what if it was simply filled with transformer oil? this alone may give enough thermal mass and conductivity to allow Johan to charge at the rate he wants one time per day. Transformer oil is stable, and non corrosive but im not sure how it would interact with what ever the module manufactures are using for isolation between cells. However if you have iso monitoring then this would not likely be a safety issue. Also the battery box could be "bunded" for safety against leaks.

There are of course more suitable fluids available but they are big $$$.

Just a thought, and I have not seen it tried yet. It's on my list to try out, but may be a long time off yet.

barracuda816 wrote: ↑Mon Jul 29, 2024 9:26 am Just thinking out loud here, but has anyone looked into a basic immersion cooling system? If the battery box does not contain the contractors or other electronics and is water tight, then what if it was simply filled with transformer oil? this alone may give enough thermal mass and conductivity to allow Johan to charge at the rate he wants one time per day. Transformer oil is stable, and non corrosive but im not sure how it would interact with what ever the module manufactures are using for isolation between cells. However if you have iso monitoring then this would not likely be a safety issue. Also the battery box could be "bunded" for safety against leaks.

There are of course more suitable fluids available but they are big $$$.

Just a thought, and I have not seen it tried yet. It's on my list to try out, but may be a long time off yet.

I think it was DIY tested and fnally rejected for some kind of active liquid cooled solution.
https://www.diyelectriccar.com/threads/ ... ar.198305/

Also any servicing would be greatly hindered by oil and goo all over the elements you needed to service...

I still think for "normal" DIY without special tools air cooling of some kind is best option. Then one would need to adapt fast charging limits in BMS. Engineering is allways a game of compromises.

So far I like the vortex tube best as it would require the least modification of the box. Second best would be exit vents in the back. Peltier might help but I can only access the lower 4 modules without a major teardown.

Oil wouldn't work as the box is tight to reject spray water but not really sealed well. Plus the only access possibility is removing the bottom cover - go figure

Tested traction control: viewtopic.php?t=6018

Small update on battery cooling. The fan proved not very effective so now I added air scoops. They can be closed off to prevent debris and water getting in on everyday driving and opened on longer trips with rapid charging. Test is pending.

And finally installed this one: These are 3 NMC 60Ah batteries. So they will sit at 9.5V when empty and at 12V when full.

I got a cheap CC/CV buck converter from ebay, supposedly up to 20A. It is a synchronous design, so not just a diode on the low side but a FET for both high and lowside. It still gets quite warm (70C) even though I set it to just 13A. The high side is always closed when there is no input voltage, meaning you get the full battery voltage out of the "input". So that is boot strapping sorted. I set charge end voltage to 12V or 4V per cell.

It is super small compared to the "80 Ah" lead acid battery and probably has twice the usable capacity. Now I also have space to mount some more terminal blocks on the DIN rail and get rid of my dodgy 12V junction box that just floats around before the battery compartment.

There are downsides of course. It is no longer a low tech solution, so if the buck converter breaks I have no 12V and the car is dead. Also it being an NMC battery it requires a BMS to keep it balanced and to prevent deep discharge.

I could have also gone for 4 NMC cells but was hesitant to run the cars systems at 16V. Also the Outlander DC-DC only outputs constant 14.3V. And if you wonder why these? Because I have them.

I still have the lead acid battery in the trunk in case something goes up in smoke
I also "hardened" the buck converter a bit by gluing down the inductor and properly bolting the FETs to their heatsink, they weren't sitting flush and one had a solder blob or something on its back. Finally soldered the on/off switch permanently on as these tend to fail over time when getting moist.

I have used 4S (used 18650s) on the motorbike for a few years now as the Kelly controller needed it. Plus, it's drain only / charged alongside the main battery. Considering downsizing it and just live with the 50-60% SOC with the DCDC's output voltage

marcexec wrote: ↑Mon Apr 07, 2025 1:47 pm I have used 4S (used 18650s) on the motorbike for a few years now as the Kelly controller needed it. Plus, it's drain only / charged alongside the main battery. Considering downsizing it and just live with the 50-60% SOC with the DCDC's output voltage

Yes we'd be at 3.6V per cell. Maybe I can trick the Outlander DC/DC to generate a bit more voltage by spoofing the sense input a bit.
With V2G I know have a use case that pulls about 0.5A for longer amounts of time without running the DC/DC.

Today I rewired the various 12V circuits: GND, permanent 12V, ignition, charge OR ignition, rapid charge, charge OR rapid charge, GND

Diodes in the back. Just see something is bent here...

Got a chance to test my cooling scoops yesterday on a 350 km trip. Outside temp was 7°C so quite favorable. I drove 250 km then charged from 25 to 65% with 200A. Battery heated up to 44.5°C. I opened the scoops and after 50 km the battery had cooled down to 37°C. Then it started raining so I closed the scoops again. Now on the remaining 50 km the battery did not cool down at all!
So it looks they work rather well. Next test is a trip to 400 km away Dresden in June, so less delta T.

Just found this thread and read all through the last few pages trying to learn of others using air cooling on batteries designed for liquid coldplates. Tough spot you're in since you can't get air between your layers! I don't have any useful ideas for that, unless you can afford 10mm. I found someone selling 3/8" thick embedded pipe coldplates (copper tube in alu plate) on ebay for $90usd. i can send the link if interested.

One industrial solution i haven't seen in a car yet is evaporative cooling. If you're feeling experimental you could consider that technology. I think of it as a middle ground between air conditioning and simple forced air cooling. It's more energy efficient than AC but not as effective. You make one side of a metal wall wet, blow air over it, the evaporation cools the metal. Air on the other side of the wall is cooled without touching the humidity and sent to the electronics. Not sure how antifreeze effects this process, but i'd assume that's been figured out. Marvair makes these for industrial applications.

Or the poor man's cooling idea: pour water all over your battery box once in a while!

I just began designing my battery boxes and there are more complexities and costs to water cooling than i had thought. My pros/cons list is pointing me towards air cooling for simplicity and better packaging!

Ah didn't see this yet. Will store it in the back of my mind.

So in-between report of our long road trip that we're now eactly 2153 km into (currently at Dombås) Not a single problem on the drive train side but one problem on the CCS side as mentioned elsewhere: on the second day the auto-wakeup died so now I'm turning on Foccci by hand.
I'm inclined to think we're travelling rather cheaply: 78,47€ for 170 kWh of public charging accounting for less than 4 ct/km in energy cost. All other charging was free via Schuko. Let alone the CO2 footprint which is actually very close to 0 in Norway.

Note to myself actually...
Ionity 42,18€ for 102 kWh (including sub fee)
EnBW 11,78€ for 20 kWh
EWE Go: 6,96€ for 13 kWh
Fortum: 8,88€ for 16 kWh
Others: 8,67€ for 18 kW I found to get the best charging experience when charging from 40 to full. That got 30 kWh into the battery within 25 minutes without it overheating. When going deeper then that it overheats towards the end. Heat loss is generally larger the lower you drop SoC because a) lower voltage -> higher current and b) apparently higher internal resistance. So the travel mode from now on will be 100->40, 100->40 until reaching the last leg of the day where we can drop to empty.

Ripping up and down the tight mountain roads in 2nd gear in the strongest regen setting is super fun, you hardly have to touch the brake ever and it's nice to see the battery fill up by 5% after dropping from 1400 to 400 m V2L is also playing nicely, have run our outdoor kitchen more than once: Only need to make sure to wander off with the dog, it hates the noise of the induction cooker!

We're nearing the northernmost part now, will soon start descending again. will have more to report

johu wrote: ↑Sat Aug 02, 2025 9:16 pm .
I'm inclined to think we're travelling rather cheaply: 78,47€ for 170 kWh of public charging accounting for less than 4 ct/km in energy cost. All other charging was free via Schuko. Let alone the CO2 footprint ....

For Europe that is cheap. Here in US I travel cheaper in my Prius but our gas prices are very low.
Do people in Europe really care about the CO2 footprint propaganda?
Never heard anybody in USA ever talking about that.

Yes though I recently saw a video from some region in the US where per kWh gas and electricity are the same price. Around here gas is 2-3x cheaper per kWh only at a higher general level than the US.

Regarding CO2 (GHG) "propaganda" that is like 200 year old science and science is what we do on this forum, right? Of course the fossil industries income stream consists only of transferring carbon from under the ground into the atmosphere. So they invest billions in brainwashing campaigns that seek to discredit actual science and get people to continue paying them billions each year for a product that they then set on fire...

Proton wrote: ↑Sun Aug 03, 2025 5:05 am ...
Do people in Europe really care about the CO2 footprint propaganda?
...

If you live with solar and renewables (i consider wood a renewable) then you dont care about CO2 propaganda. It is simply a way to do your daily routine while not to waste energy if possible. Sadly not everyone can live this way due to different restrictions, monetary or situational...

And we finish the trip with 4104 km.

Here I charge at Ionity Tangen, well known from Björn Nylands various tests: Lets re-evaluate

Ionity 82,78€ for 235 kWh (including sub fee) 0,35€/kWh
EnBW 24,67€ for 42 kWh 0,59€/kWh
EWE Go: 6,96€ for 13 kWh 0,52€/kWh
Fortum: 8,88€ for 16 kWh 0,55€/kWh
OK: 16,40€ for 45 kWh 0,36€/kWh
Others: 32.87€ for 78 kW 0,42€/kWh

That makes it 172.56 € for 429 kWh of public charging. The Ionity sub was kindof worth it but I think I'd ditch it next time. It's just too much incentive to queue up on their busy chargers rather than just using a random other one. The winner in subscription-less charging is OK in Denmark.

I didn't take note how much I charged from camp sites and other AC outlets but since the above works out to 105 Wh/km and the trip average was more like 150 Wh/km I'd say that was another 200 kWh that I didn't have to pay for.

EDIT: this would be roughly 630 kWh consumed. Had we used the Diesel it would have consumed 5.5 l/100km * 41 * 100km = 225l or 2250 kWh. That makes the EV 3.6 times more energy efficient. In carbon terms that is 225l*2,65 kg/l = 600 kg CO2 (from fuel alone, not accounting for average 20% in transportation and refining). In the Nordics it is around 40 g/kWh for 31,5 kg total - that is almost 20x less carbon emissions! Let alone all the nasty smelly stuff.

The last leg today was 550 km and despite high temperatures the battery never overheated! The trick: don't go deep and limit charge power to 50 kW or 133A. In addition I kept the air vent open all day and the fan running while stationary.

johu wrote: ↑Mon Aug 11, 2025 5:25 pm.

The last leg today was 550 km and despite high temperatures the battery never overheated! The trick: don't go deep and limit charge power to 50 kW or 133A. In addition I kept the air vent open all day and the fan running while stationary.

can you show a BMS temp graph for 100+A charging? I am curious since I use the same cells in Mazda now. I dont have real option of liquid cooling so I could use some kind of air cooling.... tnx

Yes will try to record one next time

Fixed the Foccci enable FET again and this time added a TVS across gate-source. But I somehow suspect it could have died from overheating because it was very hot and the battery was hot as well. It only needs to conduct like 500 mA and is rated for 2.5A so not sure why. Also the gate voltage would be around -9V so good saturation. (SFP9510)
EDIT: I mean the weather was hot, not the FET

While at it I also stuffed an ESP module in there and modified Petes logging code to simply log Focccis serial messages to SD-card while no device is connected to wifi.

This also gives me a nice CAN bridge into the car.

arber333 wrote: ↑Mon Aug 11, 2025 7:13 pm can you show a BMS temp graph for 100+A charging? I am curious since I use the same cells in Mazda now. I dont have real option of liquid cooling so I could use some kind of air cooling.... tnx

Just found I'd done so earlier viewtopic.php?p=73176#p73176

Oh no, yet another trip on the tow truck Drove home from visiting friends yesterday and Ines was complaining that there was a lack in power.

Then at the next stop light there was a jerk when taking off and then a rattling noise while driving. Pulled over to the next parking lot and had the car brought home.

Today I disconnected the drive shafts to figure whether the noise comes from transmission or shafts. Well hear for yourself:


I also let the car coast down our steep road with tranny in neutral i.e. motor out of the loop. Same noise.

I changed transmission oil back in June and already in Norway we found 4th gear was kind of rattly. The gear stick would vibrate while in 4th gear but not in any other gear. I wonder if I picked the wrong oil...

3rd time on the tow truck. 3rd time not related to the conversion itself.

johu wrote: ↑Mon Oct 27, 2025 2:10 pm .....

I also let the car coast down our steep road with tranny in neutral i.e. motor out of the loop. Same noise.
...

Looks like the differential gears. Do you have any torque available for return drive upslope?

What happens if you fix one wheel to the ground and keep the other one up and rotate at steady RPM?
Try both wheels

arber333 wrote: ↑Mon Oct 27, 2025 7:39 pm Do you have any torque available for return drive upslope?

What's that?

arber333 wrote: ↑Mon Oct 27, 2025 7:39 pm What happens if you fix one wheel to the ground and keep the other one up and rotate at steady RPM?

Ok, didn't try that but should be easy. Will put the car on a lift tomorrow.
So if it only makes noise on one wheel it would be the respective output bearing?

Is it possible there isn't enough plunge in the halfshafts and they're binding the differential bearings?
Seems like the differential bearings are shot. Likely something else caused their failure.
Can you drain the diff oil through a paint filter to see if metal chunks come out?

It's the original transmission in stock location so the geometry hasn't changed.
Will check for metal today and report back