Urgent advice required. I have just spent $12K replacing my clients 15kwhrs worth of Pylontech with 20Kwhrs of BYD LVS as Pylontech is blaming the Victron Gear for the fault and I want to keep my client happy so I have paid for it myself. The system incorporates a 8kw Q, 2 x 250/100mppt, Cerbo. The system is live in the VRM portal. I have many live systems with no problems. The batteries hit their 100% mark early most days but that is followed by continuous high cell alarms which have led to the eventual failure of the Ptechs (as ther was a period of no internet). The mppts and cerbo all indicate DVCC and External Control is functional. The BYD’s have been in for 5 days and whilst one might expect a couple of high cell alarms as the BMS finds the floor and ceiling I am extremely nervous that in fact the DVCC is not adequately winding back the input voltage and current as requested by the Battery BMS and that as soon as the batteries are at 100% the BMS is actually charge controlling and the Mppts are not winding back.
Anyway to get a Victron professional to have a look at the system on the portal and advise.
That new algorithm for holding back when the cell voltage is too high, is implemented only for Pylontechs with 15 cells.
Also because the Pylontechs are sending the min and max cell voltages.
Question: Are the BYD sending min and max cell voltages?
Why? Because then you can ask Victron (or do it yourself) to modify the dvcc.py script to prevent those cell overvoltages.
any update on this? did you have sufficient comms between the pylontechs and the cerbo? it should have forced DVCC on with settings for the 15 cell pylontech loaded… If you had for example charge voltage of 56.8 Volt, you would have had 3.8 Volt. Is the screenshot that you posted from the BYD battery? Those cell voltages look not good at all… you are hitting almost 3,8 V. Which is really really high. I think EVE calls it the highest allowed voltage, above that you have guaranteed damage. From my experience, BYD is very nicely balanced from the get-go.
For troubleshooting, can you post more pictures of the physical installation? Also what exactly happened that made pylontech blame victron? Can you give more insight? this is a really serious situation and if there is a victron related fault, it ought to be investigated properly…
When you say this, what do you mean exactly? BYD has to be in charge of charging. DVCC is just a way to distribute control easily. It does not actually control charging, unless you do a custom script in nodered, altering the charge voltage limit. The mppt’s are either in control, or the byd BMS is. Both are possible, but for BYD, definitely put the BMS in control and make sure the mppts have external control turned on. (see BMS menu setting)
