Cheers for that!
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I would scratch the “unfortunately”. For those who want a great charge-discharge BMS, there’s already the DieBieMS. A small charge-only smart BMS is what we’re missing. As much as I like DieBieMS, I would be more than happy to sacrifice the discharge path control for a smaller footprint.
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100% this! And the fact that some ppl don’t want something possibly failing while riding 
Last components ordered for the tester board batch from digi-key. Of course as usual, about two minutes after submitting the order I remembered that I should have ordered some crimps for the PH, XA and PA connectors… Well, just have to see if I forgot anything else once I start assembling the boards and order them later with those.
and the boards are also almost done, with luck they’ll be able to send on Monday, because they have 3 day holiday starting on 1st of October to 3rd.
EDIT: Actually I have to make another order on digi-key anyway as I have to order the parts for the first prototype 0.1 FlexiBMS HV
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I’m actually waiting on China for PCBs due to that holiday you mentioned. Good luck on your project! Any thoughts on a version for up to 20s? I’m working on a line of controllers that can go that high. Might be cool to showcase our stuff working together if 20s is possible.
Are you keeping the project files and/or schematics to yourself? just curious.
What about using 90 degree angle Xt60 connectors?
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Exacly, I build batteries all day and like one in 15 customers want a discharge type bms after explaining the difference to them
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AFAIK there is no single battery stack monitor IC that supports upto 20S setups. Biggest I know is 18S, so that means that you would have to use 2 stack monitors chained, for example 2 LTC6803s for 6-24S pack configuration, which in itself isn’t a problem, but does present more complicated wiring setup.
Personally I would stay with a single IC / single board solution, or go for distributed topology like I’m prototyping with the HV-version (high voltage).
Firmware will be open source, github page is already up in fact and have shared it with a select people from the tester enrollees, but I’m still doing base documentation and organizing in it, so I haven’t publicly shared the link for it yet.
For now I’m keeping the HW files closed to the public, but will be sharing them with the selected testers for development reasons. I’m not opposed to the idea of sharing them in the future for personal builds, but I’m more worried about them making their way into China, especially after hearing some ESC designers’ license agreements not being followed by chinese manufacturers. ofc there is the argument that if your quality is better than everybody elses and they are just producing sub-par products, then yours will stand on top, but they might be saturating the niche market for that product… There is a lot of back-'n-forth conversation that can be had about this. For now I’m keeping my cards close to myself and letting the testers have a peek at them.
What about them?
Jokes aside, for the Lite-version they need too much board space and you can quite easily solder normal ones straight to the solder pads, while still allowing other connectors or wires to be directly connected.
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Yes I’m aware that you would have to stack BMS ICs to achieve >15s in most cases. TI has “stackable” ICs that would accomplish this. Any threads or info on this “High” voltage version? How high is “high”?
Sweet!
I’m doing the same but I’m probably releasing the schematics like Mr. Vedder did for the VESC 6. What about you’re schematics? I understand if you want to keep those closed too.
Ah I see what you’re saying…
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Well for the american start-up that I’m developing it for is going to be using it for a 96S setup consisting of 8 modules; 1 master, 7 slaves, 12S each. Each module supports 3-12S and they can be then daisy-chained via real isolated comms. Bottom of the stack module will be master module and all above that will be simpler slave modules. Master module will have the comms to connect to the rest of the electrical system and has isolated contactor control, CAN, DAC-outputs, USB.
I don’t know what the upper limit for the amount of modules chained is, but limiting factor is the communications through the modules.
Is there newer HW schematics available of VESC 6 than the 6.4, which dates back to 2016? My understanding is that he hasn’t released the later version schematics?
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I’m gonna be closing the application form this week’s Friday and I’ll be selecting the testers. I think I’ll be able to announce the confirmed testers during this week.
Didn’t know he had released newer HW schematics, thanks for linking to them. I’m not opposed to sharing the schematics at some point, but I really want to get this closed release testing done first and the FW in releasable state.
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Tester Application Form - Now Closed
Participants will be informed of the selected testers this weekend.
Boards have been shipped
I should have them on Wednesday or Thursday of next week.
FlexiBMS Lite FW github repo under construction
Once SW documentation and code formatting has been completed, I’ll post a link to the repo. Testing with a closed group have shown so far 100% compile success after following a written setup guide.
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Testers have been chosen
I had a total of 14 responses with 10 people selected to receive one or two boards out of the allotted 14 boards. All applicants were notified of the results via email.
Below are the selected testers and number of boards allotted to them.
@mackann - 2
@rpasichnyk - 2
@Friskies - 2
@ducktaperules - 2
@Wisp - 1
@annihil8ted - 1
@M77 - 1
@Pedrodemio - 1
@hexakopter - 1
@glyphiks - 1
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Yeeewwww! Excellent! I will be taking the diebiems out of my current diy and replacing it with a charge only… when do you expect that these will be ready to send out @SimosMCmuffin
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If I get them on Wednesday or Thursday of next week (9-10.10) I’ll first assemble one for quick check up that everything looks ok and I’ll then start assembling them in bigger batches. I expect that I’ll have most of them assembled by the end of next week assuming that everything goes smoothly and then start shipping them out the next week after that.
So let’s just say I’ll be able to ship in two weeks.
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I reckon I can hold out til then 
excellent work mate!
Is the connection order typical for BMS’s? Never heard about it. Or is it typical for the flexiBMS design?
I can’t say. I have never used other BMS’ for my own packs so I can’t say if it’s typical for example for the chinese ones. All I can say is that connecting pack first and balance second is safer and that’s what I recommend doing.
I once burnt couple components from the balancing circuit (couple resistor and diodes, I changed them) and that was when I connected balance connector first not thinking much about the connecting order back then, so all I could assume it was something to do with that, as it hasn’t happened again when connecting pack terminals first ever since.
Hit a bit of a snag when I started doing batch assembly for the tester boards today. I ran out of solder paste… The syringe in the picture is bottomed out.
Luckily, earlier I had ordered more solder paste from digi-key, as I was starting to run low so I was kind of glad when I got the order and looked into the pack and… Well let’s just play a little “find the inconsistency in the picture” with the image below and figure out what went wrong… I have already contacted their customer support about this.
Guess I’m gonna make a little visit to the office this evening and “borrow” their non-leaded paste from the lab’s fridge, so I can continue the assembly during the weekend and likely finish all the 14-15 pieces of tester boards.
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