Do you have any proposals? Mooost likely it’s not going to fit onto the board, but I’ll look through your proposals.
I just checked the pin out on the MCU and I can get USART_TX/RX and I2C_SDA/SCL from the same pins, so I can connect them both to the 4 pin header and switch between them in firmware. You can then config the pins to use the I2C interface and connect one these cheapie OLED screen onto it, it can be then used to monitor the cell voltages directly.
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Off-topic Something interesting happened last night. Got a whatsapp message from my old employer/customer asking how much would my monthly salary have to be for me to come to do R&D for them… I scheduled a meet for coffee tomorrow to talk things through about this. Maybe I can leverage for a raise with this.
I’m just really surprised, did not expect this.
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Update. Board is routed, but I’m not ordering the PCBs yet, I need to sanity check the schematic side for anything obvious. I’m also gonna experiment with changing the layout to find something a bit more optimal, but I’m taking a snapshot of the current layout in case I can’t successfully optimize it, so I can at least order the first boards at the change of the week.
Would have updated some smexy raytraced 3D-renders, but it appears that the forum’s server has ran out of space for images 
. I’ll add them later to this post when the issue resolved (assuming it’s soon).
No space left on device @ io_write - /var/www/discourse/publichttps://esk8content.nyc3.digitaloceanspaces.com/uploads/db2454/original/3X/7/0/70ee714019eea3c91e0ac9ae0b24b97061d4e118.jpeg
EDIT:
We got Pics!!
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Since @Deckoz popularized it, there has been a few builds for sure, I’ve one in the works that this design would have been perfect for 
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One could use something like this: https://www.alibaba.com/product-detail/High-Quality-IP68-Circular-Waterproof-Male_1987076125.html I don’t know. I’m just not a fan of these sketchy pin-connectors that may come loose at any time. An other solution is just to leave some holes for the cables to be soldered into.
That is a inline wire connector, not a board header.
JST’s XH-series is pretty good connector for it’s size and price. It has detent locking, so unless it’s pulled away from the connector, I don’t see the probability of it coming loose likely.
I’m planning on ordering the boards without any through hole components, which would be the wire connectors. People can then specify when they order, what connectors they want pre-soldered. If you don’t want to use that particular connector, then you can solder your own wires onto the board and crimp your own connectors.
Looking good, what are the dimensions so far? Excluding the connectors
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62,5 x 26,5 mm
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Perfect
A suggestion, use a vertical mounted USB connector, most board won’t be able to reach it once installed as it is
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I might do the same move as with the earlier board. Make it possible to mount either one.
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I really wish you would work with @deodand and make lite version alarm Unity through CAM about cell/pack low voltage and first enable limited power mode and when voltages are critically low complete shutdown of Unity. This would let us use all the current pack can output and at the same time do it safely.
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I don’t see why that couldn’t be made reality. Mainly it’s just getting both parties to agree on the messaging protocol and then implementing it.
Or if one party has already implemented the messaging protocol, then it will be just making sure your device conforms to it.
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As the layman am I right in thinking the features each the vershion will have
FlexBMS Light Seprat cell voltage monitoring, CANbus, Active cell balancing in use.
FlexBMS Basic Same as light + Discharge protection
I’m sure things have been mentioned that have just gone over my head that I missed will try to work out what thay are. but looks as tho it be very popular for a lot of diy builds
Im on the side of defiantly want CAN with it linking to Metr pro app to see cell voltage. Been able to set min cell voltage cut off instead of a overall battery pack min. Is this some thing that could be set by consumer later or would it have to be pre set in manufacturing?
Not sure how the screen links in to it is that throu canbus as well?
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Here’s a rendering with both horizontal and vertical connectors. They can be soldered in any configuration, so you can optimize your connector orientation for your use environment.
CAN is confirmed, USART/I2C is confirmed and a opto-isolated enable signal is confirmed. I plan on first making a simple configuration interface via the USB and Serial terminal for the relevant charging and fault limits. Then in the future maybe try to integrate the configuration onto the VESC tool or metr app.
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Deadline is approaching and @ducktaperules offered an extra set of eyes to check the schematic and layout. 0.1 HW files are at the moment ready-to-order and I’m just waiting for the green light from him.
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Boards have been ordered.
I’m gonna clean up the BOM and order the parts meanwhile. Maybe I’ll comment about the component costs and quoted assembly costs once I get the shopping cart sorted.
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Nic! Keep the good work. The thing about unity and communication between bms would be awesome.
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Here’s a pie chart of how the component cost is spread between the component categories in case anyone is interested.
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Bla bla bla bla We only want to know: did you get a raise?!
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