openinverter forum

Hello,

I'm in the midst of planning my EV build and the one thing I cannot understand is how charging works. I understand how Level 2 charging works as in a dedicated charger is placed in the vehicle and it converts AC to DC. I understand how fast charging works with direct DC. My problem is with regulating how much power the batteries can accept based on voltage and especially temperature. I'll provide more details for my specific project so you can have a better understanding of what my needs are:
E46 BMW Base Car
GS450h Transmission and Inverter
ZombieVerter VCU
Tesla Model S Modules
Foccci or BMW LIM (Undecided)

That's just the job of your BMS - it will communicate with either your onboard changer - or offboard DC charger and let them know it's required charge rate.

In addition to the BSM, you can and should set charge parameters on your OBC and DC fast charge controller so that the power levels going to the batteries don't exceed what you deem safe. Whether FOCCI or LIM based, you have to set a max amperage level, along with max voltage.

To figure out what your batteries can take, do some digging around for a) what others are doing, b) how they were used in the original car and c) any laboratory testing. The US Department of Energy has done testing on OEM battery packs that can tell you a lot about their "real" limits. Most of the DoE testing I have seen has been from the Idaho National Laboratory.