Hi All,
So i have an issue with my system that i can’t seem to solve.
I have 2 Multiplus II in parallel configuration. I have ess set up in the master.
The issue i have is the solar chargers are showing a charge voltage of 60.8v
and that these are running in a networked system.
I read in the ess manual that when ESS is running they get there command from the master inverter. In the inverter the charger tab the absorption voltage is set for 56.8v and float is set for 54v
I was using agm batteries while testing my system for a number of months and had noticed high volage alarms i had set. but because 60v was not a problem for the AGMs i was using this was not an issue. now i’m using LifePo4 it is a problem. these batteries are protected by there own safety circuit and a contactor. but i don’t want to get into an over voltage situation.
currently i am using my shunt to manually set the SOC against the voltage of the pack.
inverter shuts down when present (In ESS) SOC is reached. but solar chargers continue to charge.
DVCC is enabled settings are below.
I just cant seem to find out what is causing this.
Sometimes a get a low batt alarm showing on the master when its not low,
also i have noticed i get a low #1ESS SOC when using the classic ui sometimes.
The settings in the MPIIs for charging are ONLY used for charging batteries from the AC IN (=Grid)!!! In an ESS, these settings are only failsafes to prevent deep discharging of batteries. Outside of this failsafe, these settings can be ignored and actually you can even completely switch off charging in the MPIIs.
As you can see in the DVCC settings, battery charging of the ESS is done through EXTERNAL control. This means that the BMS is in charge of setting limits.
Set your max and min values in the BMS, and everything will work. Also 60.8V for a 16s LiFePO4 system is way, way, way out of spec. The maximum voltage for LiFePO4 is 3.65V. That is a HARD limit. Your cells are most likely damaged already.
Not sure if my explanation came across correctly. (Maybe google translate or something)
I’m not charging my cells at 60v i know perfectly well what is and is not ok for LifePo4 cells.
I never actually stated that i had these in a series of 16.
I have a 1s 4p configuration of modular packs with their own protection.
these packs can connect to Victron equipment however at present they are stuck in another protocol. so i am using another function available to protect the installation.
below is the band i have to work with.
Also i am aware the settings in the inverter are for when its charging (Mains Grid)
but the info below i got off the instructions from the ESS manual says that the MPPT charge parameters are ignored when ESS is set up and that they follow the charge curve set up in VE configure. well the only charge curve that i can see is the charge curve is the one you set up for the Inverter.
From what I’ve been told and are running, SVS, STS, SCS should be off on a non-managed Lifepo4 bank.
Ps. I have no connecting between the BMS and the Cerbo/Venus.Running “native”.
SOC coming from a Smartshunt.
Smartshunt and BMS SOC (using the BMS App) close as can be expected most of the time.
Maybe give that a try until someone knowledgeable comes long?
Yes, read carefully. It may be using the ve.configure charge curve values to over-ride the solar DC-DC converters.
I have not noticed this behaviour in my Victron System. In my system, ESS values indeed override MPPT DC-DC converters. BUT, voltage setpoints will always get over-riden by BMS values. I have also not noticed any change in solar battery charging behaviour if I switch off charging in ve.configure.
Yes, it sucks that it appears that no matter what you do, the shitty BMS always overrides everything. I would love to have a more adaptive load curve that load currents are reduced when cell voltages are above 3.3V.
Thanks for the reply Jaco,
I have tried the settings you recommend its not changed anything.
I’m thinking of deleting the ESS and see if that changes the charge voltage.
Like you i’m using the smart Shunt for SOC. i have set it up at 55v is 100% for now. so i’m well away from the 58.1v limit. but like i say the inverter follows the shut and shuts down but the solar chargers are just ignoring. i could disconnect the ve direct connections but then loose the data an remote control.
Agreed i would expect the BMS to override all charging based on pack info. but god knows what’s telling the chargers to go to 60.8v as BMS is not connected.
Still thanks for replying.
It is a good idea to familiarise yourself with the DVCC chapter in the Cerbo guide.
I think some things are being lost in translation, so need to clarify a few points.
ESS assistant must be installed and configured on all inverters, though the master drives what it does.
It is a good idea to always program the mppt’s, just in case.
With managed batteries (doesn’t apply to you yet) the BMS runs the chargers, with conventional batteries, the inverter’s algo is used.
Some settings always apply, for example if you limit the mppt charge Amps, that will override the battery and inverter if it is lower than what is asked for.
You can also connect a BMS and tell DVCC to ignore it.
