Hello Community! Happy to be here:)
My headache is to combine 4 or 6 individual LiFePO4 16S packs together and use the whole as a power system based on Victron toys.
For the moment my experimental setup contains:
5 x old Li-Ion 12S packs with no BMS(!) at all
2 x Victron SmartSolar MPPTs 150/35
6 x 420 Wp PV panels
1 x cheap chinese 2500 W inverter
Victron Cerbo GX with Touch 70
Victron SmartShunt 500A/50mV
For the moment all good as for experimental phase:) Recently new toys arrived:
3 x Victron MultiPlus II 48/5000/70
32 x 324Ah LiFePO4 cells
So i invested quite a lot for the hobby up to now:D:D
…and the problems started: BMS solution. The plan is to add 32 or 64 more cells. Final plan is to power my entire house by 3 MultiPlus 5000 VA inverters synced in 3-phase system.
The issue is i can’t make bank configuration like 16S4P because i can’t find proper BMS solution, DC breakers for the current required by 3 x MultiPlus II 5000 VA inverters! Fully loaded, they will draw like 300 A and can easily exceed 500 A in short periods.
The only solution i can see now is to split the bank to 16S1P units with 200 A JKBMS each. This way it is easy to find 200 Amps rated BMS, fuses, cables, MCCBs etc.
And here we go - 4 BMSs can’t talk to Victron Cerbo GX just like that.
Do you guys know any solution to gather all the data from individual BMSs and then provide Cerbo GX with correct data for display/trending/statistics purposes so i can monitor my big battery via VRM?
Just to add: i’ll add more SmartSolar MPPTs for battery charging power and i plan to add one or two AC coupled Fronius inverters on AC OUT side, controlled via phase shifting.
Many thanks for putting some light on it. Any ideas highly appreciated!
Why.not look at a single BMS for a larger system such as from REC that can interface properly with Cerbo GX via CAN Bus, has high rating contactors, precharge unit etc.
There are third party scripts you can add to the GX device to aggregate multiple BMS boards but these are not without their problems and are not supported by Victron.
I have a pair of 280Ah LFP batteries, each with a JK inverter BMS. Those are connected to a single RS485 port, interfaced with dbus-serialbattery and aggregated via batteryaggregator, so VenusOS sees them as one big battery.
One issue that bothers me (but is not a big functional issue) is that the current sensors on those batteries are pretty crappy and hard to calibrate, so the two batteries show 5 or more percent points of SOC difference after a few days of not reaching 100%.
Haven’t heard abour REC BMSes. Probably they are not popular in europe? But those BMSes don’t have MOSFET disconnection functions, right? I can see no current ratings. Looks like they are for voltage monitoring only with no current sensing.
Can [quote=“Christian Mock, post:3, topic:6312, username:cmock”]
dbus-serialbattery
[/quote] be used on Cerbo GX? I’m not using RB Pi with Venus OS.
I now think that I’ll go with individual BMSes from JKBMS and let them do their main job - monitor their respective cell pack and disconnect by built-in MOSFETS in case of over/under voltage issues. Total SOC (for all the banks) will be handled by Victron SmartShund 500A/50 mV (have one already) and that’s it. ANL fuses will handle protection functions.
I have 3 separate battery banks with JKBMS, all 3 connected via 3 RS483 to USB.
The nice thing is I can see each of the 48 cells individually in Cerbo GX, and that makes if possible to keep track min and max cell voltage in all 3 battery banks in VRM.
Best part is the advanced Charge Voltage limitation so the total voltage is controlled by the cell with the highest voltage. In my opinion it is the best solution. It is also possible to connect JKBMS via Bluetooth, al tho I haven’t succeed with that.
I can recommend you check GitHub - Louisvdw/dbus-serialbattery: Battery Monitor driver for serial battery in VenusOS GX systems.
WOW! Looks like this is the solution i’m looking for! What JKBMS model are you using exactly? You meant RS485, not 483, right? So if you are using 3 x RS->USB dongles connected to Cerbo GX that means you are using powered USB hub to connect all of them to one Cerbo USB port, right?
I’ve seen Louisvdw GitHub now - can’t find how to use it on Cerbo GX device. Do you know any tutorial showing it?
What is the amps rating of your JKBMS? 200A?
Many thanks!
EDITED: ok i found wiki on this subject. Will try once i gather all the elements. Looking very promising:)
@TRSK - do you mind to send some photos showing your setup? What type and rating of fuses have you used. And where? My plan for fuses is ANL type, each Victron MP II 48/500 to main DC bus bar via ANL 200A and each 16S battery bank to main DC bus bar ANL 300A or 400A.
one thing: make sure to use the serialbattery script from GitHub - mr-manuel/venus-os_dbus-serialbattery: Battery Monitor driver for serial battery in VenusOS GX systems as mr-manuel has taken over development (but the wiki is still with louisvdw, a bit confusing).
You also don’t need a RS485-USB adapter for each BMS, as they can be daisy-chained via the RS482-2 connectors, just make sure to not set them to address 0, but each one to a different address, and then in config.ini use
Regarding "Remote Battery Switch (500A) from TBS Electronics EN - it is twice the price of JKBMS 200A i bought 20 minutes ago:D I think i will stick to BMS;P
So final version is a bunch of 16S1P banks instead of making less banks with parallel cells inside. The reason is currents. With 16S2P approach BMS capable of doing 300 or 400 amps is way more expensive, using 200 A will reduce charging capacity. By using 16S1P approach i can easily and quite cheaply make 4 or 6 banks with total capacity of 99 kWh (i’m using 324Ah cells), individually connected to main DC bus bar with negative bus bar leg going via Victron SmartShunt and connect as many solar chargers as i want to achieve max 500 A charging/discharging currents. Should be enough for averange Joe and his garage;P
Yes of course RS 485. And I use a non powered USB hub.
I use these 200amp JKBMS in picture below. I have an old Victron solar connection box with busbars, shunt and 250amp fuses inside. The box is from the time before the LYNX system.
I would like point you to a tutorial, but it’s long ago, I think I found out this solution from DIY solar forum.
I think you should follow link @cmock provided that is more up to date.
Thanks @cmock for the link and info. Interesting to use one RS485 to USB and change the addresses. Also would like to have the Bluetooth connection to the battery/from my forklift. When not in use I can connect it to the victron system.
Can the three batteries be connected this way with one USB cable connected from the converter? I don’t want to connect them with three separate wires. Can we connect the batteries to other ports on the Cerbo than the USB?
Also take a look at https://123electric.eu/ BMS from the netherlands which also works perfekt with Victron GX and multiple battery banks and external circuit brakers for safety. Drawback: Its much more expensive than JK BMS.
I use 123electric BMS with two 90 + 200 Ah LiFeYPo4 16s Banks which consists of used cells from chinese EVs in parallel with two 180 + 400 Ah Lead Acid 48V batteries which are also second hand.
So with those crappy batteries a good BMS with lot of fuses and breakers is essential for safety.
What JKBMS model are you using exactly? You meant RS485, not 483, right? So if you are using 3 x RS->USB dongles connected to Cerbo GX that means you are using powered USB hub to connect all of them to one Cerbo USB port, right?