Id3 Battery withe 12 cells

[Michi202020]

Hello, I am new hear in Github. My English is not the best but I hope you understand me. I have 14 peases from this block and I will create homestorage withe your system. At this time I have install 3x6,85kwh Id3 and 2x6,85kwh. The big problem is the wire ring from the battery to your v4. 4 board. My idea is that you can create a board from 6 cells to 16 cells and in the software you can switch on or off the Funktion how many cells are installed. For example I install on the 16 cells only the Id3 12s and the last 4 is deaktiviert. I think it's better than on the market are not enough attiny841 and one chip for 16 cells are easy to create. I have one gay more he will also build storage withe your system. Pleas let me now what can we do or I can create the board but I need only a person what can write the code. I am not good in this.

Best Regards Michael

[fhorst1]

Dear Michael,

Each cell can function without any BMS. You do need to manually watch it like a hawk and manage it accordingly..

DIYBMS works with 1 cell module per series set (can contain more then 1 cell in parallel)

Removing or disabling a cell module, see first comment .. You need to do manually.

The global chip shortage hurts all sectors, including this DIY part.

Yes, they can re-invent cars to function without the chip that has shortage, they don't. Much cheaper, safer, more efficient is to simply wait for the chips.

Lucky for us, there are MANY different BMS available, many lower costs then the DIYBMS.

While most lack power in the balance part (Daly does only 0.08A), an additional balancer is cheap and widely available.

With higher capacity setups, you where already using contactors instead of MOSFET based.

Any 10A BMS can manage 1000A installation, if you let the MOSFET of the BMS control the contactor. (Using a small switch to power the high capacity one)

It does not have to cost a lot.

Obviously, the design of DIYBMS didn't forsee that the widely available and known attiny would get a shortage.

Change to different chip isn't that easy. Change to totally different system and setup (not individual cell modules) will take a long time and is a totally different product.

Many DIY members feel and share your pain, waiting for their backorder for months and months.

I was "lucky" and obtained for my 4 X 280Ah sets enough attiny chips to populate a 5th one if needed.

Yet.... As BMS is so crazy important. I have all 4 also equipped with Jkong 2A active balancer BMS.

Redundancy is key :-)

4 X 14kwh isn't cheap and any sunny day can push a cell beyond its maximal voltage if there is imbalance.

My motto: Better safe than sorry.

Cheap BMS, 100A contactor and 1.2A balancer can be bought for around $40-75 (globally from Asia) (S16 setup) DIYBMS won't be cheaper.

If you want to have the same functionality... Professional alternative is quickly +$750,-

Re-writing the software to function with different design of PCB and/or different chipset will take weeks, months probably. With lots of testing, magic smoke and buckets of patience. It's not that easy as you hope it would be.

I take this opportunity to thank Stuart for all his time and effort and all the others in the community that helps.

Probably not the response you hoped for, it can give you the tools to proceed (for now) without DIYBMS, and get "standard" product to protect and use your cells.

Shortages don't last decades.

In 18-24 months there will be enough attiny available at a price of under $1 (back to $0.80?)

Unless China goes to war also... Then not having attiny is a minor problem :)

Frank

On Tue, 24 May 2022, 00:21 Michi202020 @.***> wrote:

Hello, I am new hear in Github. My English is not the best but I hope you understand me. I have 14 peases from this block and I will create homestorage withe your system. At this time I have install 3x6,85kwh Id3 and 2x6,85kwh. The big problem is the wire ring from the battery to your v4. 4 board. My idea is that you can create a board from 6 cells to 16 cells and in the software you can switch on or off the Funktion how many cells are installed. For example I install on the 16 cells only the Id3 12s and the last 4 is deaktiviert. I think it's better than on the market are not enough attiny841 and one chip for 16 cells are easy to create. I have one gay more he will also build storage withe your system. Pleas let me now what can we do or I can create the board but I need only a person what can write the code. I am not good in this.

Best Regards Michael

— Reply to this email directly, view it on GitHub https://github.com/stuartpittaway/diyBMSv4/issues/117, or unsubscribe https://github.com/notifications/unsubscribe-auth/ADVGBDBGFEDTMJFEF7JHVXDVLO5A7ANCNFSM5WWRFSRQ . You are receiving this because you are subscribed to this thread.Message ID: @.***>

[Michi202020]

Hello Frank,

That's not what I mean. I find the bms from Stuart is very good and the price also. I pay a little bit more and I have a good system. If you install a Id3 or a other car battery that you see that you become for 12 cells only 13 wire and you welding from board to board a bridge and better in this situation that you youse for the contact screw terminals. I will sent pictures for understanding.

[fhorst1]

Thank you for your pictures!

I can see some challenge solder work :-)

I love your neat work and 3d printed casing for the cell monitor PCB's!

Most people use JST connectors (2.54 or micro)

Some members adjusted the PCB so they have 4 (or more) cell monitors on 1 PCB.

On openenergy community you can find more information about this https://community.openenergymonitor.org/t/diybms-v4 It's a bit a search to find :-) "John_Tavis" was working on it last year.

I'm still confused about your part: "My idea is that you can create a board from 6 cells to 16 cells and in the software you can switch on or off the Funktion how many cells are installed"

Software solution would be a huge hassle to program software switches. I assume it's a one time installation, and not changing 4 to 16 cells on regular basis...

Jumpers would make that more easy:-)

No software changes needed. But you do need 16x attiny.

Whole new BMS system with different design, and different IC per cell is always an option. That would be DIYBMS#2.0 :-)

For many builds, having separate cell modules where the cell is on the battery, the longest cables are the TX/RX, not the power to the battery.

For pre-build units like used in cars this is different. There the communication between the boards is short wire and makes one wonder why 13 separate PCB's ? As the leads to the battery are the longest cable and the cell PCB's are nicely grouped together (In your setup extra nice!)

It's not difficult to make 4 to 16 cell modules on 1 larger PCB and connect the RX/TX on that board. Also not too hard to design and make 4,5,6,7 and up Gerber files.

Each cell has its own JST for power. One RX, one TX JST that leads to the controller board. ( What also can be in the same PCB if you like)

I assume most people know how many cells they are going to use before ordering the PCB :-)

Heck, it even can be breakout like the temperature sensor mini PCB on the V4 cell PCB :-)

You can break off if you like :-)

For me, using EVE 280 lifepo4 Having the individual cell design works best for me. Easy to replace if something would go wrong with the cell module.

I guess that is also the original idea behind individual cell modules.

The flexibility :-) Making one board will make that an issue.

You can make totally different product, with electronic switching, using less resistors 2 or 3 banks that can be used by the cells that need it. Perhaps even dynamically. More out of whack, more amperage allocated to burn of the rest.

Limiting the amount of parts needed. That would be a fun project.

Perhaps jumpers aren't needed as you have a default: power. No cell connected is no power on that section. With normally open and normally closed relays you can activate a part of the PCB as soon as it has a battery connected on that section. (Just brainstorming here)

Different processor (we can call attiny a processor?) Would require a ton of work, starting almost from scratch. Learning new language, new layout.

I understand that Stuart is looking at ways for some time now to phase out the attiny.

There is a reason why this chip has been around for about 25 years, even planes use them.. Rock solid, reliable.

Arduino Nano ($1.00) for sure could handle lots of cell modules.. It's a whole different scope and project.

It already would be amazing if Stuart would be able to replace the attiny with the nano (or Uno) They are, for now, available.

Attiny (and most other chips) are expected to have end of the year abundance.

Creating a multiverse(ion) for 4-16 modules is an idea that many people like.

With the same components it's not difficult to make, and no change of software is needed.

Jumpers to select/ make the number of contacts that is needed, or relays activated my the power of that cell module.

Software solution, what would need different chips.... That's a whole lot of work.

And would mainly take out one of the main features of the DIYBMS: Cell monitoring on the battery. Not via a long cable, making the commonly known spaghetti for 98% of commercial available BMS.

Amazing clean installation you have there! My compliments!

And I do understand why for your kind of installation having the cell modules combined in one PCB - makes sense. Except it won't be cell modules anymore :-)

Perhaps someone could design and program a PCB compatible with DIYBMS controller that is better suitable for car batteries. I still would not make that programmable, but automatically with relays, battery attached, or not.

I like the current setup. Each module keeps function even if the controller isn't working (for what ever reason... (Someone (kid) needs the USB cable... You name it.) Burn off excessive charge still works, 99% of the time with our powerful cell modules, that is all (with a balanced pack) that is needed anyways.

I have lost a setup due failing (Daly 250A) BMS.. That was expensive experience, with bad support from Daly. (They concluded it's defective, fully epoxied, no repairs possible. Yet for refund they needed return.... =$75 postage fees) With this experience, I absolutely love the function of the DIYBMS, keeps working even with failing controller.

[stuartpittaway]

With the existing module design having very short wires to the cells is critical.

They must also not share the same wires.

You will run into balance and voltage reading erros if this isn't followed.