After I eventually got my BMZ working with my setup (MPPT 450/100 and Multiplus) I had an event that blew a 100 a battery fuse and caused battery BMS to safe mode. The event was caused by my EV charger coming on outside of the scheduled time when the ESS programme was in battery delivery mode. The battery protected by the 100A fuse can only deliver 5kW so the EV requesting 7kW blew the fuse. I obviously did not set up the ESS properly to avoid this happening. (The battery is still locked out and still working on that problem). I am going to upgrade battery to Pytes V12 and I want to know how to prevent this happening again. One way would be to get the V16 battery that will deliver 10kw but I do not have the space for it. I guess there must be a programmable way to prevent a recurrence.
Why didn’t you configure an inverter limit in ESS?
Your system is mismatched which is never a good idea.
Having an inverter that is way larger than the battery is best addressed by configuring limits to prevent overloading and not having to rely on fuses which are there to protect the wiring not the battery.
Although have a smaller inverter would have been the better move since space is a issue so adding to the battery was never going to happen.
Please bypass the system untill the battery issue is sorted as running without a battery reference is detrimental for the inverter power pack.
Thanks nick.
Because I thought it was done in DVCC which I believe was uploaded from the BMS.
Not sure what you mean by this. I replaced a Delios hybrid inverter that died with a Victron setup based on the size of the Delios, array 6kW, and the 10 kW battery that came with the inverter. I chose Victron because of stated compatibility with BMZ.
Again not sure what you mean here w.r.t inverter bigger than battery, but I agree that configuring the limits is the way and I thought that the ESS I had set would have covered the eventuality hence the title of my post. I am fully aware that fuses are a last resort. It is unfortunate that Octopus turned on my EV charger befor the scheduled time, they have not done that before but then it would have happend at some point.
I have looked into the battery parameters and in there there is a max discharge current of 270A !! how that got there goodness knows. I did not enter it and don’t know how to change it either
There is an added complication I found delving into it a bit deeper that the Victron BMZ set up document does not always reflect what is on the Cerbo. Seems the GX been updated but document hasn’t or the updated is there but the one I have has not been deleted.
If your battery can only deliver 5kW and you’re capable of pulling far more than that and blowing the fuses then there is a mismatch.
Any battery should be capable of delivering the peak supply of the inverter and loads connected to it, if it cannot then the inverter and loads are far too big.
A 10kVA multi can peak at 18kW - you would want a pack capable of dealing with 400A.
As a side-note this tends to result in high discharge/charge rates which is lousy for battery life.
Thank you LX
Thank you will check that out the title makes sense.
For brevity it has become ambiguous. My space is limited by the shape of the outbuilding it is in and stuff already on the wall. I can in fact get 3 Pytes V12 in there the V16 is taller. I could fit V16 on the outside wall but gibbing a bit on that as we are in a cat 4 area for weather and despite the V16 being IP66 it could get a battering unless I provide additional shelter.
Thanks for the advice fortunately I have hardly had the inverter on not been much point. Was on for a few minutes to look at the ESS settings earlier.
The battery seems to be working from all that I can make out. Is there anything in the victron settings that would cause the battery to go to idle or not allow it to function normally? I did manage to get a service software to run on the BMZ and the report stated that it was good and there is no reason for it to go on idle. Searches elsewhere suggest the BMS has locked it down but the report did not indicate that. The data from that, corresponds to the Can bus data
Possibly with battery life enabled and temperatures that are cold? Not usually idle though so a stab at an idea.
As long as there is a new fuse iguess a bypass isn’t necessary. Therr needs to be a battery reference.
Should be able to do 12kW easily if that is true. That would be what is sent to the system by the BMS of the battery so is not editable unless the bms was preprogrammed manually.
If they aren’t playing nice then maybe disabling DVCC might be worth it (if everything has been programmed conservatively).its the only way to rule out battery interference. Does the BMS need a keep alive signal?
Many thanks,
There is a new fuse.
The label on the battery entlandestrom meaning discharge current states 300A so commenstruate with the BMS
Tried that did not have any effect.
Yes but battery will stay on for 20 mins on loss of BMS signal.
Have done this, easy enough when one knows how. Was previously at 1000W. Now 5000W Wish had known that before. There is so much Victron documentation difficult to know what you need to know.
Lol. You are right is is so configurable its crazy, but that means there is a huge learning curve.
(And yet still also many complaints here from some users about a lack of enough documentation 
.)
Just realised the setting how much to restrict DC to AC does not make sense the default in there was 1000W so that did not prevent what happened. Expecting new Pytes batteries this week supplier will set up the configuration remoteley for me. The BMZ was a pain will no practical knowledge around and clearly there was more to it than I found documented. Thanks to all that contributed to helping get the BMZ operating which I did in the end apart from the mishap with the EV charger.