@Louisvdw, that’s good to know, so it is really an unnecessary hack then (if you have a BMV already), but someone somewhere without one, may want to do it. It’s very simple.
Edit: My VRM is down so I can’t check these things, thanks.
Edit: Edit: I am going to pass on your driver info to the guy who made the BMS video above. He said he’d like to make a clip about how to set it up… you’ll be famous.
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Ha! So long as I am not (in)famous
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The extra publicity should bring you some.
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MOSFET switches can only switch off in one direction. So in order to fully isolate the battery, there are always two MOSFET switches in series.
This means 2 things:
- It is possible to turn charge and discharge on and off separately (there are power limitations when only one is on though.
- It is possible to center tap the two series MOSFETS and have separate charge/discharge ports that can be isolated separately.
This functionality is inherent when using bidirectional MOSFET switches.
Yes, I am counting on that, but I’ll just be driving relay coils or optocouplers so I won’t have any power limitations deal with.
@Louisvdw,
I saw some discussion about being able to monitor multiple banks.
1.) Does this mean seeing multiple BMS within VRM?
2.) If you may I select which BMS is the master that instructs the other gear?
3.) If this isn’t possible yet, is it something that is likely to happen in the future?
Thanks.
I assume this is because the inherent body diode is less efficient at conducting than a turned-on MOSFET? 
From what I googled on the subject – since I am not an electronic engineer – the “body diode” thing is also somewhat of a simplification. Not all MOSFETs are equal when it comes to reverse conduction.
- No you will see 1 BMS (or more accurately 1 battery) with a combined capacity, combined power, SOC etc. of all the banks. Each BMS will be a battery module.
- The BMS that connects first will be the master in the GX, but each one is still managed individually meaning you can have one blocking charge while others accept charge. The current limits will be adjusted according to how many modules are available to accept or give power.
- It is on my TODO list issues, but my second BMS is still in China waiting for a RS485 chip to become available
Below is a screenshot from the GX. Here you can see the Battery banks and also how many modules block charge/discharge.
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Thanks, I’ll design my balancing around that then.
Have found another supplier … just waiting for an invoice to pay. It is said they will have RS485 chip in. So cross your fingers.
@Phil.g00 , where did you buy that BMS?
This is the one I bought.
I didn’t buy the 200A solenoid one, although it is for sale all over Aliexpress.
This is the design I am thinking about. ( I may have the shunt wires reversed to the BMS (B- and purple), but that will become obvious, once it’s running).
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Naaa, won’t work.
Need more cells. 
It’s all right, I was a single cell once. They multiply.
I just got a message from Aliexpress, this BMS is a custom order will take some time.
Do I want to change it for the one without the P- outputs.
I looked at my order and discovered I had in fact mistakenly had both types in my shopping basket and by accident I had ordered both types.
So, I said No, I could wait, but to please change my order to two of the BMS’s with the P- outputs.
Then I cheekily went on to ask that if these were a custom order, could I get an RS 485 port added and still keep the Bluetooth.
I was told yes,at which point I cancelled the UART-usb converter order as I already have 485-USB converters.
Well there you go.
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I find, and I may be biased, Aliexpress more expensive than Alibaba … at least with the Jiabaida BMS’s.
And shipping sometimes expensive or “Not shipping to South Africa”.
But that is me, I don’t mind making U-turns. 
You are right about that, but on some products Alibaba doesn’t want to know if you are not ordering 50 units. Also Aliexpress is more geared towards impulse buying, Alibaba often means enquiries about the price of shipping and personal interaction. I use both websites depending
Not only that, I saw a stat that “only” 11% of postage items go missing in South Africa.
So I am, getting my gear, ( well at least items under 23kg) while I am in Ireland. I have a couple of years until retirement.
Once this Covid is over, I will be a frequent flyer to SA, with my maximum quota of suitcases every time.
I have just asked the aliexpress rep, to ask the engineer tomorrow, what is the highest current rating he can customise a 20S BMS with B-, P- and C- outputs.
I need to switch 600A for the entire bank, and that just isn’t doable with a single inline BMS.
You’ll notice in my 4P design, I do not have parallel busbars ( down the way), most people do.
Those extra busbars are fine when things are working, but to my mind, they have the potential to deliver far too much current from everywhere when there is a faulty cell.
So I don’t like the design, the HA02 balancers perform a similar function but are current-limited and can be fused. ( And I already have them).
However, I am toying with the idea of doing away with the HA02 balancers in my design and putting 4 20S150A XiaongXiang BMS’s + a 40A BMS as in my design.
This will give me the option of controlling the entire bank as described, but I can add an inline BMS into every battery string, and be able to isolate a single string if a single cell starts playing up.
But, it looks like they only go up to a 100A (off the shelf), so we’ll see what the engineer comes back with.
Edit: Rethink, if this custom option is available, I will just go with 5 identical BMS’s ( and not get the 40A version), so I can have a spare if one fails.
Edit; Edit: Actually, if I am going to isolate on a per string basis, then I don’t need two discrete outputs on those inline BMS’s, I only need 1. I just need two discrete outputs on the overall BMS that speaks to the Victron. So I can use those off the shelf 200A solenoid BMS options. Which gives me more headroom and I prefer a solenoid to FETs. So the 40A option is back in the frame as the overall BMS.
I have asked if 1.5m balancing cables and temperature sensors are available as well.