B250e Battery Pack (My Curiosity...)

[FordAnglia]

Greetings,

We know that the B250e has a Tesla battery pack, and a usable capacity of 28.6kW. That's an 80% value, so the pack is 35.75KW. (rounded to 36KW)
We know that the Tesla Roadster, Model S, and Model X, are equipped with 18650 Li-Ion cells to form battery packs. The packs are made of modules, and the modules are made of cells arranged in "Series and Parallel"

How are these arranged? Has anyone done a tear down?
How many cells do we have in the B250e?

TLR? 3072

Here's my math, welcome any corrections or clarifications on my assumptions.




Peter,

 

[JeffRay]

Man, do I feel aged. Over my pay grade sir.

 

[FordAnglia]

Man, do I feel aged. Over my pay grade sir.

Looks like I may have to revisit this data, now that I can measure the high-voltage battery. I was expecting a few more volts.
Until someone tears down a B250e we're only guessing at how many cells are under the vehicle.

On eBay someone is parting-out a Tesla Model S. I got a couple of 18650 size cells from him, they're fun to pass around socially as we talk about EVs. Except mine don't have the Tesla logo, like this stock PIX


Peter,

 

[Rianmilne]

I have one of these I used for my solar battery system. These are twelve sets of 7s batteries in them that make a 300v system. Each set has 7x 44 cells in it.

 

[FordAnglia]

Greetings and Welcome,

Are you also a B250e owner/driver?

Peter,

 

[Rianmilne]

Hello

No I am not a driver of this car, just bought the pack off a wrecker.

rian

 

[FordAnglia]

No I am not a driver of this car, just bought the pack off a wrecker.

Rian,

Cool! Did the pack come from a B250e, or a Tesla Model S (or other EV using Tesla technology)?

I'd certainly like to know more about your project, and especially if the pack was from a B250e.

Peter,

 

[Rianmilne]

Sorry forgot to upload these last time

https://www.imgurupload.com/image/R65zU
https://www.imgurupload.com/image/R626D
https://www.imgurupload.com/image/R6cNg
https://www.imgurupload.com/image/R6kaT
https://www.imgurupload.com/image/R6uP5

 

[FordAnglia]

Sorry forgot to upload these last time

(links to images - deleted)

Thanks for posting your battery pack PIX! I have lots of questions, I hope you can stick around here to answer. It's a bit off-topic for the B250e crowd, we can take the discussion off line, to save cluttering up this venue.

Before I forget to mention, this forum can't use the embedded IMG tags. The best way to upload images is to use the imgBB tool (imgBB.com) and embed by cut and posting the "BBCode full linked" in your posts here. The tool is free.

Big question, is your High Voltage pack from a B250e? I assume the orange squares are safety caps over live terminals? Do you have a way to re-purpose the Tesla BMS (and sensor boards in each cell cluster)?

Very interesting project! Looking forward to learning more from you.

Peter,

 

[user 1812]

Hi,

Thank you for sharing.
This is definitely no clutter. This is interesting stuff!
Please tell us any info you think is worth of sharing.

If you have any info on the history of the pack (distance driven and age), the it would be interesting to know what is the remaining capacity.
Price would be interesting also.
Are you going to use the battery pack with the original BMS or just use the cells?
What you are using the batteries for?

Jarkko

 

[Rianmilne]

Yes this is from a b250e. The date of manufacture on the batteries says 2017. The pack was bought from bumblebee batteries and came out of a wrecked car, here was some small damage the the outside case but it’s made of some pretty thick aluminum so everything inside was fine. Paid 5000$us for it.

The bms has been a really hassle. Since the hear packs are 7s and not the 6s found in models s and x the bms is different. There is code on github to control the 6s systems but it doesn’t work with these right off the bat. I am not the greatest with coding so it has sort of stalled. I did get the slave board to turn on by feeding the 5v and disconnecting the master board. Have been monitoring them and it seems like the will passively balance the cells but I am not certain yet.
I use this for my off grid farm in bc Canada. Runs the house. System is always evolving when I find a new product or a better way to do it. Just installing a heat pump this week.

Cheers
Rian

 

[FordAnglia]

Yes this is from a b250e. The date of manufacture on the batteries says 2017. The pack was bought from bumblebee batteries and came out of a wrecked car, here was some small damage the the outside case but it’s made of some pretty thick aluminum so everything inside was fine. Paid 5000$us for it.

As MY2017 was the last for the B250e your donor vehicle was probably low miles (hours) and your cells are "like brand new" capacity. That's probably the going rate for a salvaged High Voltage battery pack.

The bms has been a really hassle. Since the hear packs are 7s and not the 6s found in models s and x the bms is different.

Even reusing the Tesla pack and BMS has been hard for PV (and wind?) homebrew projects. I dip into YouTube when time permits. I'm just a B250e pilot, and not actively doing any homebrew or experimenting with the cells. I have three "18650 cells" for social show and tell as I'm still a new EV owner.

Have you run across Jack Rickard (at www.EVTV.me)? Interesting personality and has some great insight and hands on with Tesla EV teardowns. Will use up all your spare time as his presentation style is err.. Far from Terse, more like Verbose, Long-winded, Rambling at times.

There is code on github to control the 6s systems but it doesn’t work with these right off the bat. I am not the greatest with coding so it has sort of stalled. I did get the slave board to turn on by feeding the 5v and disconnecting the master board. Have been monitoring them and it seems like the will passively balance the cells but I am not certain yet.

The cells are in modules and stacked to get 300 - 350V, as I'm sure you know. This means that the monitoring electronics are not ground-referenced. There's an opto-isolator to overcome this problem, but digital status should be available. Others have used Arduino (or Raspberry PI) micros to talk to the slave boards, and effectively by pass the BMS. Jack Rickard is/was making standby systems much like Tesla's Powerwall last time I dropped it to his channel on YT.

Are you rewiring your cells and modules to be parallel connected and lower voltage (7 x 3.8 = 26.6V) ? Not sure what you have shown in your earlier PIX.

I use this for my off grid farm in bc Canada. Runs the house. System is always evolving when I find a new product or a better way to do it. Just installing a heat pump this week.

Cool Project!

Peter,