2 x 100amp BMS or 1 x 200amp BMS? - 24v 460Ah System
- Thread starter blipohm
- Start date
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
8 cells is 24V and with 230AH that's it that's all, how are you getting 460AH ?
1 BMS & Fuse per Battery Pack. Fuse sizes to Max Load handling of BMS so 150A BMS Pack would be fused for 150A. **
** A Parallel Bank is Fused / Breakered for the Bank & System Throughput. This is separate from the battery packs themselves.
1200W @ 24V = 50A
The cells can do up to 1C Discharge (230A) but can only take 0.5C Charge (115A) Max.
A 200A FET Based BMS will be comfortable and unstressed up to 150A discharge but would only allow for 100A Charge Rate MAX.
Remember that Battery Packs in Parallel divide Charge & Discharge between the packs.
Currently the Popular FET Based BMS:
JBD, JKbms which are also rebranded by various vendors.
Features, Functions and Capabilities vary such as Active or Passive Balancing, BlueTooth or other Communications etc.. Of course Price is affected by such. NOTE a BMS is a Critical piece of kit that protects the Big Bucks in cells sitting there, it is NOT the thing to cheap out on !
I have run many different BMS, some cheap and some crazy pricey! I am now converting my "Fleet" of 5 production Packs (30kWh) and 3 Utility Packs to JK-BMS with BlueTooth, CANbus, RS485 and 2A Active Balancer. Info Below for your reference.
JK-BMS [24S 2A 150A BT] with BlueTooth Part Number: B2A24S15P $143.29 USD
Product Link: https://www.aliexpress.com/item/1005003104573871.html
plus add: CANbus Module + RS485 Module $7.73 USD each
Product Link: https://www.aliexpress.com/item/1005003451100409.html
Hope that helps, Good Luck.
You may also want to Download this Resource to help you assemble your pack(s).
Luyuan Tech Basic Lifepo4 Assembly Guide
1 BMS & Fuse per Battery Pack. Fuse sizes to Max Load handling of BMS so 150A BMS Pack would be fused for 150A. **
** A Parallel Bank is Fused / Breakered for the Bank & System Throughput. This is separate from the battery packs themselves.
1200W @ 24V = 50A
The cells can do up to 1C Discharge (230A) but can only take 0.5C Charge (115A) Max.
A 200A FET Based BMS will be comfortable and unstressed up to 150A discharge but would only allow for 100A Charge Rate MAX.
Remember that Battery Packs in Parallel divide Charge & Discharge between the packs.
Currently the Popular FET Based BMS:
JBD, JKbms which are also rebranded by various vendors.
Features, Functions and Capabilities vary such as Active or Passive Balancing, BlueTooth or other Communications etc.. Of course Price is affected by such. NOTE a BMS is a Critical piece of kit that protects the Big Bucks in cells sitting there, it is NOT the thing to cheap out on !
I have run many different BMS, some cheap and some crazy pricey! I am now converting my "Fleet" of 5 production Packs (30kWh) and 3 Utility Packs to JK-BMS with BlueTooth, CANbus, RS485 and 2A Active Balancer. Info Below for your reference.
JK-BMS [24S 2A 150A BT] with BlueTooth Part Number: B2A24S15P $143.29 USD
Product Link: https://www.aliexpress.com/item/1005003104573871.html
plus add: CANbus Module + RS485 Module $7.73 USD each
Product Link: https://www.aliexpress.com/item/1005003451100409.html
Hope that helps, Good Luck.
You may also want to Download this Resource to help you assemble your pack(s).
Luyuan Tech Basic Lifepo4 Assembly Guide
If you are building a single 24v battery, you want a single 8S BMS. 200A gives you a lot breathing room/safety margin for your max expected load.
Also, as Steve mentioned, 8 x 230Ah cells in series is just 230Ah
(series = volts increase, parallel = amps or amp-hours increase)
Also, as Steve mentioned, 8 x 230Ah cells in series is just 230Ah
(series = volts increase, parallel = amps or amp-hours increase)
Thanks Steve for taking the time to reply!. I've had a quick read through and will read over again tonight and unpack all you say. Good point about not skimping out on BMS. Cheers!
Thanks Dzl! Yep newbie error saying 24v 460Ah... was still thinking about the original 12v battery I wanted to build.. But from what I hear doing the 24v configuration will put less strain on certain components, especially in Australia its easy to get 24v equipment like ..air con, fridge and lights. Cheers
Hi Steve, thanks for that link! I think I get it.. the 24s 2A 150A will be fine for 1500watt max draw. As its not "24v" (like Daly BSM list) you must select how many cells in the software and you just don't use the rest of the wires (only use 8s of 24s wires). Is the 8s 2A 200A suitable too, OR you would pick the 24s in case of future expansion?
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
All of my stuff is 24V and standard 8S Packs, so I will be using 8 Leads and the rest are "parked". 150A model can easily handle 125A safely which translates to 3200W (uncorrected). I, like most everyone else derates the equipment for safety margin, always. I decided AGAINST the 8S-200A variant because I wanted BT,CanBus,RS485 and a few other features. Simply put, I'm replacing a couple of grand worth of BMS' along with Active Balancers, Solid State Contactors & Relays and a lot more with these... so for whatever that's worth.
Future expansion would require changing from 24V to 48V to go from 8S to 16S and that is outside of my plans.
Future expansion would require changing from 24V to 48V to go from 8S to 16S and that is outside of my plans.
Thanks Steve.. Its funny how you thought you had a handle on something, and yet you were only looking through a small window from 50' away ;-)
My build is for a van.. I thought Victron gear looked affordable and ok. I now am grasping that the BMS might talk to the charger and inverter etc. I assume (had a look and couldn't see any immediate post on the subject) that the JK BMS may be able to talk to Victron gear?
I will look into this more tonight after work, thanks in advance for you past replies as they have helped immensely!
Not sure about the JK BMS, but generally speaking, you are not going to get any "talking" between BMS and chargers/inverters, until (1) you get into higher end BMS's, OR (2) you are technically capable programming the components to understand each other and play nice together. I think maybe this is something that could be changing, or might change in the future, but as it stands right now, it doesn't seem like there is really any communicating between commodity BMS's and other components without a lot of custom work. Many share a common physical communication standard but it seems to end at that most of the time with the commodity stuff. I hope that my impression is inaccurate, I have been out of the loop for a half year or so, so it may be in need of update.
What is more feasible and common, is using the BMS to control external devices in an on/off open/close manner. This is a lot simpler and many devices are capable of this level of basic control/communication.
How are you intending to use the Canbus/RS485 Steve? Or is it more of a 'nice to have' that might be useful in the future?
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Pending on timing etc, I may be able to setup a RaspberryPi with NodeRed connecting everything together for Midnite & Samlex via ModBus the BMS' with either Can or RS and still have the BT for all of those as well. I have other priorities and the option is there for later.
Edit... looking back at another comment.
Many people think Ohh some BMS (Battery Packs) can interact with my Inverter/Charger or AIO and that takes care of everything. Sorry NOPE !
What the different BMS' and AIO or ComBi's can do with each other varies a LOT. In most cases it is limited to "Turn On/Off" or "Start/Stop Charging or Inverting", that's it, that's all. Advanced Tier-1 Products (read $$$) with their own "Family" Battery systems can do more, including charge regulation and temperature management (heat & cool) and more. Then there is More Advanced Multiple Pack interlinking and THAT is yet another new ballgame. Addionally the Big Gotcha that folks get caught up with, is when there are Multiple Packs within a Back that interacts with an AIO for example. Server Rack type Battery Packs which have advanced comms that can "daisy-chain" together with a central controller can deal with that as it coordinates the whole strings activities related to the AIO. Some of these have drivers for Victron and are tested & approved for use with certain brands & models of AIO's such as Growatt or Smart Inverter/Chargers.
** The JKBMS have the firmware & comms interfaces that can be handled externally and there "may" even be drivers for Victron Software (dunno) and if so, to what extent it would do ??? These also cannot "daisy-chain" so an intermediary would be required for scale use.
From a SW Engineering & Communications side, many of these things can be done with an external system that can interact with all of the equipment using appropriate protocols. It is one thing to "read" in the data from various devices and create a display interface, it is quite another to actually write settings and values to them. One wrong posted command can toast the firmware ! Fortunately with development systems like NodeRed for example used with a combination of other tools can be used to present a display as well as sets of commands to act upon that can control relays or send signals to devices. There are other ways to do so BUT it's not a toss it together in a day thing. A Good Thread on a Great Project is right here: https://diysolarforum.com/threads/off-grid-solar-battery-monitoring-and-control-freeware.6662/
There are also software systems available like https://esphome.io/index.html
Last edited:
Thanks Rocketman! I had a look at them before... out of my budget unfortunately, but would be worth it for a house system. The system I will build is for a van and will get minimum use. I was ready to buy a Daly 24v 8S 200amp, but am unsure now.. will keep researching!!
Cheers Steve... yep that's a box of worms I wont open!! The JK BMS still looks interesting (the manual for it is "heltec"?) and the price is less than I was going to spend. More research I think..
For a plain bms - I have also used Overkill- it does a good job and has on off switch.
Overkill is an “American” brand of one of the Chinese bms’s. Since you are down under - it would probably be better to order directly from the Chinese company. (It’s been mentioned many times - I just don’t remember it).
Overkill is an “American” brand of one of the Chinese bms’s. Since you are down under - it would probably be better to order directly from the Chinese company. (It’s been mentioned many times - I just don’t remember it).
Zwy
Emperor Of Solar
I run a Daly Smart 250A with the display in my truck camper. Largest load I ever put on it was the roof air at 1200w. Handled it fine. Roof air is coming off, I have mini split sitting here waiting for install.
I prefer derating the Daly to 50% of it's rating. 125A would be tops I'd ever consider putting on it, I don't think that will be a problem in the truck camper.
Here was the build: https://diysolarforum.com/threads/heres-my-truck-camper-setup.29488/
JBD
Hi Dzl... apologies in advance for stupid question ...
In what way would you use a BMS to switch off an external device?
Would you tell the inverter to turn off due to low voltage?
In your opinion ..should I really worry about any of this level of system interaction ? (for this van system at least)
Cheers
Thanks to Dzl I thin it JBD BMS .. unfortunately after a "quick" look it seems they only go to 100amp
Zwy
Emperor Of Solar
That is 2400w, don't forget that. I own a spare Overkill 24V 8S for "just in case".
