Francisco's Electric Pajero

[Rusdy]

Machinist and controller design your like superman

One short from superman status tho'. But not hard to catch up php codes.

[francisco.shi]

Your comment about catching up with php got me thinking about the pictures. I wonder if I can put the picture as a HTML picture link. So here is a test.
So here is a picture of the inverter cad model.
<img src="https://photos.app.goo.gl/GADGHhgUx2t3LvvDA" class="postimage" alt="Image">
See if this works.

[brendon_m]

Sort of works. I have to click on the link to view the image, it's not embedded in the post

[rhills]

The Forum software filters out ordinary HTML to prevent hackers from abusing a forum.

You can insert image links via the standard forum [ img ] tag like so:



Unfortunately, Google seem to have "fixed" their photo links to prevent you embedding them on HTML pages and that's why the above link doesn't work. There used to be an option when creating a link to a Google Album photo to make the link "publicly viewable" but that seems to have gone now.

[francisco.shi]

I have sent some of the parts for the gear box and the transistor pack coolers. It turns out I can get them made in China and shipped for about the same of what the material would cost me to buy. So now I am waiting for the parts.
In the meantime I figured I would work on the batteries. The biggest problem now is I need to get a model of the bottom of the car but I can not do that without removing the transmission, engine, fuel tank, exhaust etc. So I decided to buy a rolling shell from the wreckers. The benefit is I can use it as a test bed to get everything right before I disassemble the working vehicle.
Here is a picture of the bottom of the Pajero. https://photos.app.goo.gl/GFcfRSNyoTCcsT3BA
Here is a picture of the CAD model of the bottom including where the motors will go I have taken a guess about the size of the box for the inverter.
https://photos.app.goo.gl/wWJNWtHgtnrQVbVJ8

[francisco.shi]

After getting the model of the bottom I can now start to work out how much space I have for the battery pack.
Here is a picture of the model with the battery pack.
https://photos.app.goo.gl/E6qJgNRy54eqaP6P9.

I decided to use the E63 LG batteries.
Battery specs:
Nominal Voltage : 3.6V
Nominal Capacity: 63Ah
Dimension : 330(L)mm*120(W)mm*12(L)mm
Weight: 969g
Continuous discharge rate: 2C
Peak discharge rate:5C

I will be using 3 cells in parallel
This is a preliminary model of each 3P cell with cooling plates between each cell.
https://photos.app.goo.gl/FJcMwZBAcVHDqXPPA
The battery pack will be 189Ah and I can fit a total of 103 3P cells. (3P103S)
Here is a picture with the battery pack box with the cells inside.
https://photos.app.goo.gl/XsHLSzFguon64sqs7
And here is a test run of the cooling plate. I just had to make sure I could make the cooling plates.
https://photos.app.goo.gl/2jcfNQ3U4uZVyfFP9

Unfortunately to get the full power that the motors and inverters will be capable off I would need 10C peak. So I will have to run at lower power.
My priority was more with total energy instead of straight out power.
It may be possible to get more than 5C if I cool the batteries.

I am still working on how to get the water supply to all the cooling pipes and how to get the bus bars in.

So far I have ordered 40 Cells so I can make a trail pack and see how things go. I will also use these cells for testing the BMS and the inverters.

[Richo]

It may be possible to get more than 5C if I cool the batteries.

Usually the internal resistance plays a part.
Increase the current the terminal voltage drops further.
So increasing current / C-rating may not increase the peak power.

It will however give it to you a fraction longer.

Still 300kW is better than nearly everyone

[francisco.shi]

The batteries have arrived.
After getting the batteries I measured them and I found the size was not the same as what was on the drawing. The size on the drawing included the edge of the pouch which is folded in the real battery. Also there are some other minor differences. I had to update the CAD models. The good thing is that they are a little bit smaller than I originally thought so it will make it easier to fit. The bad thing is that I have had to spend a lot of time updating the model because I have had to move all the cooling pipes and bus bars in the model.

Here are some pictures of how they look.
The batteries finally.
https://photos.app.goo.gl/5BMwJdv5AknaQjm59
This is the cooling plate that goes between the batteries. It has a cooling pipe on each end.
https://photos.app.goo.gl/r9WKBKud2tLpHuyK7
Close up of a partly assembled pack. The connections will be totally enclosed by the cooling system. I think after it is all assembled and the batteries are clamped to keep good contact with the cooling plates that the cooling pipes will be strong enough to hold the batteries without having any extra structure. So the box will not have to be as strong. I still need to clamp the to see how strong it is after clamping. I put some weight on the batteries to simulate some clamping force. If left without any clamping force they use up much more space and there is not enough contact with the cooling plates.
https://photos.app.goo.gl/A889D7QWj7iTv7gn6
Here is a view of one string of cells.
https://photos.app.goo.gl/xqwGrcZRgUBrQYze8
https://photos.app.goo.gl/gcbNtxCm1REFj28r7

[brunohill]

I like it. I will be following your progress for ideas on how to replace my leaf battery in a year or three. What is left of the originals can replace the lead acid batteries on my solar hybrid system. Maybe I can convince my electrician son that this is what he should do with his Pajero.

[Richo]

This is the cooling plate that goes between the batteries.
https://photos.app.goo.gl/A889D7QWj7iTv7gn6

Seems overkill. Are you sure you need to go to all that trouble?
I'd go -

C
B
B
C
B
B

Guess it really depends on how lossy the battery is and how much each plate can cool.

[francisco.shi]

I am trying to keep the battery temperature as even as possible. If I only cool one side the other side will be hotter. The heat would have twice the distance to travel. The cooling pipes are also part of the structure that holds the batteries together.
It may not be necessary but it doesn't take much more effort to add the extra pipes and cooling plates. In the worse case the batteries will run cooler than they have to and will add some 10kg or so to the pack weight..

[francisco.shi]

If you want to do another pajero let me know. Should be easy enough to make another set.

[francisco.shi]

Today I did an initial trial to see if I could assemble the battery pack. I have only got 40 cells so I made just two rows of the longest module.
The battery pack including the box is 1.8m long.
I have done some measurements of the bottom of the car and made a CAD model. So I made a model in real life to see if I had got my measurements right.
https://photos.app.goo.gl/MJwT8qGN8MDT1Ybc6
https://photos.app.goo.gl/MJwT8qGN8MDT1Ybc6
It was made out of cardboard which turned out to bee too flimsy to be able to be put in easily. So I made just a base out of playwood and there are a few little details I had to adjust.
Here is a picture of the wooden base.
https://photos.app.goo.gl/nPurhXepaFzKsqAv9
View of inside.
https://photos.app.goo.gl/1hCGzVzaubPzByeAA

Side view
https://photos.app.goo.gl/yNCErjkMKVf7ACCn6

I should have more ground clearance than what it had originally.
Battery assembly test
https://photos.app.goo.gl/zRw5NzXUpwwb9s3FA

https://photos.app.goo.gl/cjDGAEhT9A6DNKG56

Section specs so far are:
7kwh, 34.3kg including water cooling and braces.
The distance between the supports in the picture is 1.6m and the weight on top of it is 16kg.
I put the weight to test the strength of the assembly. It seems it would easily take 50kg in the middle with no trouble.
All going well the 72kwh pack will be around 350kg plus the case. With luck total pack weight will be just under 400kg.

[Damon500]

Great to see your progress Francisco, looks like you have thought it out well. Have you found a good VASS engineer to certify your modifications for registration?

[francisco.shi]

No. I haven't got anyone in mind yet. Can anyone recommend one?
I hope he doesn't want to see too many orange wires because there won't be many to see. I expect there will be less than 1m of external high voltage wiring and it will be so far inside that he will probably have to remove covers and look really hard to be able to see them. The battery pack will be sealed. (Watertight) and the motors are so close to the battery pack that I will be lucky to have 10cm of cable between the battery pack and the motors. The inverter will be built in the back of the motor so no external wiring will be needed either.

[Damon500]

I would happily recommend if you are in Melbourne except mine is retiring at the end of the year hence the deadline pressure...
Ask around the AEVA members in your area- I was fortunate to meet up with the Geelong branch of the AEVA, they are a teriffic group and have been very helpful in getting me travelling down the right path.
If you haven’t already done so have a read of VSB14 which outlines what is required: https://infrastructure.gov.au/vehicles/ ... an2011.pdf
It would be highly recommended to start with an engineer early in the project as it will be much easier to incorporate their recommendations now rather than reworking later- in my case he was interested in the structural integrity of the modifications and quality of workmanship at this stage of the project.
He has also raised the issues of braking performance, suspension strength and weight distribution- although the last item is generally improved over a standard ICE vehicle it still needs to be documented that the suspension is strong enough to carry both the batteries and payload as well as the braking efficiency against regulations. In your case towing capacity may well be altered. There is also the issue of the structural integrity of the battery box against standards and where mounting points feed loads into monocoque or chassis.
Hope this helps- at the end of it somebody has to sign off that in their professional opinion your modifications are safe for both you and other road users- the more you involve them and build confidence in the execution of your conversion the easier (and cheaper) it will be to make it legal.

[francisco.shi]

I agree. At the moment it is still early to discuss modification details. From an electric point of view there will be almost no external high voltage wires going anywhere. Probably under 1m of cable that you could get to without cutting thru some metal case. As for the weight I am still not sure how much the original engine and transmission exhaust and fuel tank weighs but the total weight of the system will be around 500kg all included. My guess is the difference in weight won't be much. Remember this is a heavy 4WD a full fuel tank is already over 100kg. It has a steel engine block and a big heavy transmission with transfer case.
As for the mounting of the battery to the chassis of the car it will be very straight forward. The chassis already has many holes that are suitable for inserting nutserts. I don't think I will have to cut or drill into the original frame at all except for removing some hooks for holding the exhaust and fuel tank and they are just brackets spot welded to the frame.
I have read the requirements and the only concern is the 20G crash requirement for the battery. If the battery weighs 400kg I will need to provide support for 8000kg. Sideways is not a problem because the battery sits inside two main structural members of the car. The forward requirement is a little trickier.

[jonescg]

Good effort on the cooling channels. I'd advise you cover the cells in some kind of contact plastic so the foil can't rub against the cooling surface. Kapton would be expensive but polyethylene is possibly OK.

[jonescg]

@Richo if the cells have a very low DCIR it's probably OK without a cooling system, or at least a fairly simple one will work. But the high energy density pouch cells are typically in the 20 mOhm range, so a 25 kWh battery is likely to dish out ~4 kW of waste heat at 2C. A sealed battery would warm up pretty fast otherwise.

[francisco.shi]

I am currently charging the battery so I can do a capacity test. I assume a 63Ah cell should be able to push 63A for 1hr from fully charged to fully discharged?
After the capacity test I want to run a 5C discharge test and test the cooling system. I still don't know what to use as a load. I will need a 35kw load. Any one have any suggestions?

[jonescg]

You will only need to produce a 315 amp current. A coil of MIG wire around a ceramic support, submerged in water will work.

[francisco.shi]

Sorry. I did not specify the currents correctly. The pouches are 63Ah but there are 3 in parallel. So 5C will be 945A
The segment I have assembled for testing is 10S3P. The expected capacity is 6.993kwh hence the 35kw load. So I do not think the mig wire will work even if it is under water.

[jonescg]

I'm working with 44 volt modules of 72 Ah, so they too would need some hefty testing equipment. Although I would never expect to see more than 2C peaks (140 amps).

[francisco.shi]

During normal operation I think will only be around 2C. But the motors will be capable of drawing 10C. And another reason for testing at 5C is I want to get some figures of how efficient the cooling system is.
The cells are rated at 5C so I will be limiting the maximum output to what the batteries can take.

[brendon_m]

I couldn't find a full spec sheet on the cells but what I did find said the cells were nominal at 1/2 c, so they may not rate when drawing at 2c. Can the cells go at 5c for a long time or is it only for a minute?