Hi, so - I’ve scanned the forum and sorry if I might have missed something that already explains this, but:
From my understanding the WatchMon is the perfect BMS to use with the Sungrow SH10RT due to the BYD emulation. I have a total of 96 modules from two 2012 Nissan Leaf batteries. The SOH is about the same.
SH10RT works with a voltage range between 150 and 600V. The modules are configured in a 2S2P config, where each string has a max voltage of 4,2V (nominal 3,75V). So using 48 modules I can build a 48S pack at 403V peak (nominal 360V). That leaves me with the options to use 1 pack, using half my modules, 2 packs using all of them, or building a 600V using about 70 of them (that makes the max voltage end up at ~600V).
Has anyone done this, and knows for sure that the SH10RT accepts that voltage using the BYD protocol? I mean, everything points towards it, but I don’t want a surprise like “bYd sHoUlD bE 600V oNLY” or similar.
What exactly do I need?
I guess I need at least 1 WatchMonCore and 48/16=3 CellMate K9s? Is the ShuntMon a must for the BMS to be able to report SOC to the inverter, or will the inverter calculate that itself?
Additional information:
This is for my house. Today I also have a Fronius Gen24 with a small 10kWh pack attached to it. The Sungrow is already installed, from a previous installation I had for some other stuff.
My plan here is to use the Sungrow to store the surplus form my solar array attached to the Fronius, meaning that I will use the Sungrow to charge the batteries connected to it, instead of exporting it. During the Swedish winter I would like to charge it during the cheaper hours instead. This will be controlled by Node-RED from Home Assistant.
Both inverters have smart meters, so I’ll figure out that config later on.
Can you double check your maths on the 2S? My understanding is that the Leaf modules are 7.4V nominal (2x3.7V). So with 48 modules it would be actually be 96S. Cells in parallel don’t work like loads in parallel (like speakers etc.)
There are 2 things to keep in mind for HV inverters:
Current is often limited to 50A or 100A, so you sometimes don’t get the full output of the inverter unless you reach a certain pack voltage.
Some inverters need a fairly high startup voltage of 150-200V, factor in the pack voltage decreasing as it drains, 48S is borderline in some cases, 96S is definitely fine.
Please get expert help if this is your first pack, HV packs are more dangerous and tricky to get right. While we can provide guidance, the project is yours.
Hi, yes. Sorry for mixing the terminology.
The modules are internally a 2S2P configuration, and the chemistry seems to be LiMn2O4 with LiNiO2, hence the difference in voltage compared to “the usual LiFePO4”. From what I’ve read they are indeed 3,75V nominal and 4,2V max.
I was confusing myself in the moment of writing, sorry for that. But yes, 48 modules makes a 96S, ending up at 360V nominal.
Since I have 96 modules to spare, I can build two packs of 48 modules each, and run in parallell if that is something WatchMon likes (this is where my knowledge is limited). But your information regarding the 48S borderline makes sense.
To reach maximum voltage for the SH10RT (which is 600V), I can use 160S (or 80 modules). However, I am not a stranger to voltage, risks and the actual work performed, but I am new to the calculations. Is an inverter rated 600V specifying nominal or max voltage?
If I go for the higher voltage, I get a lot of cells in spare (which of course can be used for something else).
But regarding the design and configuration, I guess I should go for a single pack, and the parts I actually need would then be the WatchMon, a shunt and a K9 per 16 cell?