Tesla charger udclim and udcspnt

[mane2]

Could someone please explain udclim and udcspnt parameters?

udclim is the voltage limit where the charger - does what? Stops charging completely until power cycle?
udcspnt is the voltage limit where the charger keeps the battery at?

How have you set these? udclim always 400V and udcspnt to whatever charge target SOC you want, like 380?

[tom91]

https://openinverter.org/wiki/Tesla_Mod ... 5_Software

Says it all here

[mane2]

I Googled those parameters and used search here but for some reason, that page didn’t come up. Thanks

Posting it here if someone else is wondering the same thing.

udcspnt
This modifies the constant voltage setpoint of the chargers. This value is transmitted directly to the modules without further processing. It lets you add a constant voltage phase to your charge process. When reaching this voltage the chargers will control the current to maintain this voltage.

udclim
This parameters specifies a charge end condition. When the voltage is hit the charging process stops and will not resume until you re-plug the charge cable. If you wish to add a constant voltage phase and control charge end by your BMS, set this parameter higher than udcspnt.

And to answer my own question: I was pretty close with my initial guessing. udclim stops charging and udcspnt keeps charging going while maintaining target voltage.

[Zieg]

The one part of that I haven't grasped yet is how the BMS would control charge end? Is that for topbalancing or something? If you don't have that ability but you set udcspnt lower than udclim, I assume the current would taper down until it hits some lower limit and then stop?

[tom91]

It works like a power supply, so the charger will only output as much as udcspnt ever, the udclim is there and meant to be hard coded and not changed on the fly.

The BMS should then raise the udcspnt only if the highest cell is not fully charged yet.

[Zieg]

Oh okay, that makes sense. So unless your BMS can speak canbus to the charger, it sounds like using udclim is the way to go.

[tom91]

Your BMS should ALWAYS talk to the charger. Specially since this charger can output alot of power.

[Zieg]

Hmm, does anyone know if any guidelines have been set up for doing that? I searched before and didn't find much in the way of what kind of communications are needed. I know mine (Dilithium/Thunderstruck MCU) can pull a pin low when charging is permitted (ie temps are ok, no voltage faults etc) but not sure how I would use it to control udcspnt.. Maybe I should ask in the support thread.