Hack DC charging - limit to 30kW

[dracekvo]

Hello,

There is someone clever person? My question is simple. Is a way how to limit DC charging to 30-40 kW?

[DBMandrake]

In what circumstances and to what end ?

Keep in mind that the maximum power (current actually) is negotiated between the car and the charger. The charger is able to signal to the car the maximum power that it can provide, and there are actually many 22kW Chademo rapid chargers out in the wild that don't operate to a full 43kW.

[dracekvo]

In my head is solution. Replace battery LEV50 to 18650 cells (25pcs). But here is limit to charing current about 80A (30kW).
In my country is only 50kW chademo.
This is too much for battery from 18650 cells. If I will use this charging method, battery will be quick degradation.

I mean. Somewhere in car software must be value where is write maximum DC current. But question is where. And how to change it.

[DBMandrake]

I understand now.

Ultimately the charging current decision is made by the BMU, so the cleanest way to achieve it would be to reprogram the BMU to limit the maximum charging rate.

Actually doing that though would require an ECU modder who was willing to reverse engineer the firmware in the BMU - not an easy task I would think!

The other option would be to intercept the Chademo communication and insert a "man in the middle" device that understood the protocol and modified the communications between the BMU and the Rapid charger unit. Also not easy.

[kiev]

i wonder if the temperature of the pack could be used to throttle back the DC charging current?

For example use some sort of variable voltage to simulate the pack temperature and fake out the BMU.

[Don]

Maybe source a better 18650 cell?? Some Teslas came equipped with 18650's and they don't mind charge currents a lot higher than 30 Kw

Don

[kiev]

Tesla uses active cooling with a liquid loop that touches each cell, so they can push higher currents than a passive or air-cooled system.

[Don]

Tesla uses active cooling with a liquid loop that touches each cell, so they can push higher currents than a passive or air-cooled system.

True, but not all 18650's are created equal, are they? Some can safely be recharged at a higher rate

Don

[dracekvo]

Yes, high drain cell is way. But
I find Molicel 2000mAh. If I will use 25pcs cappacity will be 50Ah. No range upgrade. No sense try replace LEV to another cells.
Molicel have 6A charge current. 6x25 = 150A. Nice for imiev.
https://nexun.pl/pl/p/Molicel-IHR18650C-2050mAh/592

Is Molicel with higer capacity 2600 or 2800mAh with 6A charge too. But price is too much.

https://eu.nkon.nl/rechargeable/li-ion/ ... ah-5a.html
https://eu.nkon.nl/rechargeable/li-ion/ ... h-35a.html

[coulomb]

Actually doing that though would require an ECU modder who was willing to reverse engineer the firmware in the BMU - not an easy task I would think!

I have tried to do that. I have had no success getting to the BMS master firmware; I've had limited success reverse engineering the CMU firmware.

I'm not aware of anyone that has achieved this, so sadly, I think that the temperature spoofing or the CAN in the middle solution are the only viable solutions.