2008 Nissan Quest Van with Tesla SDU.

[Proton]

I was looking at ways to passively cool the batteries using a liquid.
Trichlorofluoromethane refrigerant R-11 has a boiling point at 23.8C. was thinking at a closed loop that goes outside the battery box that cools the vapor and transforms it back into a liquid that has a lower temperature.

here is an exaple of a fridge that uses Ammonia - boiling point -35.5C.

https://web.archive.org/web/20011104153 ... IceBox.htm

https://www.engineeringtoolbox.com/boil ... d_155.html

[johu]

Isn't vapor cold and liquid hot? So a classical heatpump. I think OEMs use it but usually have a heat exchanger to water to avoid high pressure lines throughout the car.

[Proton]

Isn't vapor cold and liquid hot?

You might be right. I guess I have to do more research. I am thinking that if the vapor is sent in a heat exchanger outside is transformed back in a liquid that is pushed back by gravity in the battery box cooling it.

[Proton]

did you win as its not viewable any more... do you have the bmw 330e over there as the 12kwhr batteries are relatively cheap (this side of the Atlantic) and its a good starter battery

I looked few times at the BMW batteries and they are too heavy. From my calculations they are 101W/kg. that is very low.
BMW batteries have 12kw at 261 lbs / 118.4kg

That compared with new CALB batteries that are 245W/Kg, that is 41kW for 96 batteries at 168Kg.

Screenshot from 2023-12-13 14-31-12.png (10.74 KiB) Viewed 281944 times

I decided that I just want to install the batteries in the front of the car. Because of that I cannot go with LiFePO4 and I need to go with NMC 3.7V cells. that will be 168Kg.
If I go with LiFePO4, they will not fit in the front and have to split them in 2 packs, which means they will have different temperatures and need to be cooled/heated separately, which I do not like.

The only problem is that si never bought batteries from this seller.
https://www.alibaba.com/product-detail/ ... 4e62mI7slL

[m.art.y]

That compared with new CALB batteries that are 245W/Kg, that is 41kW for 96 batteries..

What if you find a nice 40 kwh Leaf pack with little use? Wouldn't it be better and more cost effective than shipping them from China? Leaf 40 kwh is NMC and a good stable chemistry. Also it will have a BMS inside. Nice shape modules as well.

[Proton]

I was not able to find the individual cell specs. but for the whole pack Leaf 2019 looks the best. The 2015 pack is not very good.
Thing is that at 410Kg I cannot install it in the front.

Screenshot from 2023-12-13 15-56-08.png (15.47 KiB) Viewed 281922 times

https://www.batterydesign.net/nissan-leaf/

[johu]

I use the Leaf 40 kWh pack and the cells alone are 210 kg

[Jacobsmess]

But all the above is pack weight, which is irrelevant if you aim to repackage cells. Packs vary in design a lot depending on their placement, structural application and cooling design, you'd be better off determining your desired capacity or the capacity you can accommodate in the battery pack space and then find cells to suit IMO.

[Proton]

Thanks to Alibro I was able to save the can messages from the 2nd car. Not sure I will need them but I saved them just in case.

Alibro's video to setup this contraption:

[Proton]

back at it again.
I just got the new batteries. unfortunately I had to go with Lithium batteries because they are lighter and can do 3C discharge rate.
I also ordered from China some fiberglass separators between the batteries.
They wil be
mounted in the front. Engine + transmision was 240Kg and 41kw of batteries are 258Kg.
on top of that the exhaust pipe with cathalitic converter are about 25kg, and the Gas tank 16 Galons is about 50Kg.
overall the car will be lighther with this batterie. the other option was the 140Ah batteries but they were 192kG.

I asked them to weld the studs with the square base, so the busbars have more contact surface.

[Proton]

This is 6.8Kw, 16S pack. I will have 6 of these.

[Proton]

I will have to test the batteries. I asked the seller few times if the batteries have a barcode and every time she said that this battery type does not have a barcode. the barcode was scratched. I will see the performance after install.

https://www.alibaba.com/product-detail/ ... 2fc2JzcQC5

[Jacobsmess]

johu: quote redacted

I mean this guy sounds like a douche but I'm confused as to why you've posted this here?

[Proton]

I mean this guy sounds like a douche but I'm confused as to why you've posted this here?

Just to see how people think here maybe? He is a douche but I totally agree with his message in this video.

[Proton]

This is 2 rows with 32 batteries each. I have to add another row on top to have 96 batteries.

[Proton]

I will post the progress moving forward on my you-tube channel.

[Proton]

I just want to mark this as complete.
Conversion is complete but does not work because connected the 12v battery in reverse which caused some fuses to blow up but also I am guessing damaged the board and possibly the Tesla inverter.

[johu]

Congratulations (to finishing of course)

I don't think the Tesla inverter took damage as it has reverse polarity protection, both the logic board and the power board.

EDIT (after watching the video):

Do you have a solid ground connection to the inverter? The contactors will pull a surge from ground and if that isn't stable the inverter might loose power.

The OI BMS is available in case you want to use it

[Proton]

@ Johu

You know what. this gives me some hope. I do not have the guts to tell my wife that I have to buy another Tesla motor and board.
I have to check the ground. I will check that later today.

[johu]

Re info from PM:
You have fixed the motor case grounding which is good but it seems power supply to the inverter is not stable. How much current does your contactor consume?
5.32.R gives the BrakeCheck status because cruisemode != Off so it wants to see the brake pedal once at startup. After that you will loose the web UI anyway as that is caused by the contacto surge

[Proton]

After work I will load 5.27R since that was the software that worked before, and I do not have a wire from brakes connected to the board. and load the default parameters for 2.19R. Those are the last default parameters published.

I will also use clean power and disconnect the car from the 12v battery, so only the Tesla board is connected.
the power supply will show me how much power is used by the board.

https://openinverter.org/parameters/view.html?id=27

https://openinverter.org/parameters/

[Proton]

I made a video to be easier to understand.
Since I do not have a break cable connected I Downgraded to 5.27R. that code worked before.

I used a different switch for forward and reverse and also used the Prius Pedal that I used in testing before.

[johu]

If you disconnect the relays from the inverter does the web interface then stay alive?

[Proton]

If you need I can upload the video.

I disconnected the 12v from both precharge an HV relays and both went off. refreshed but data was not populating.
All this time the computer stayed connected to the inverter. Double checked that.

[Proton]

So..... do not connect the battery in reverse.

I had a remote session with Johu and it looks like some mosfet(s) got fried. KNB2804C
I was not able to find the same online but another one that will fit.
It is going to take about 3 weeks from amazon to ship it. hopefully that fixes the problem.