DIY 6S to 12S BMS with CAN - DieBieMS

Updated my wiring diagram to show the intended power LED switch wiring. Ignore other versions of this figure in above posts, I’d change them but can’t edit my old posts. The issue was that I had the LED between 3v and LED Smart, when it should have been between LED Smart and GND. This worked, but the LED does the opposite to what jtag intended (it’s actually not as bad as it sounds :wink:).

diebiebms_wiring

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Another happy DieBieMS user here. Such amazed!

https://www.electric-skateboard.builders/t/no-words-just-pictures-delete-words-use-pm/2992/6240?u=rpasichnyk

Can we have new firmware (binary file) with push to start (external CAN power up)? Will be adding support to Metr app and need a little help @JTAG :wink: When charger plug is connected do not shut down VESC (make this configurable). Please please

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Yes yes, will make this available asap (I am currently on a holiday in the UK and am only allowed minimal “hobby” time (she is asleep now, sshhhh dont tell her!))! As soon as I am back at my man(only)cave I will build and test a version specific for esk8 (recently I added a bunch of stuff to make it useful for an e-foil, I will need to retest everything when that is all disabled). Directly after releasing that ill finish the user interface for the computer and that will allow you to possibly implement some of those interfaces in your app, and man that would be freaking awesome!!! :heart_eyes::heart_eyes:

Yes charging during discharge is already coded into the firmware and is configurable ^^, I actually wrote it to allow me to use the TCP - bluetooth - vesc - can - bms bridge :blush:.

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@JTAG about the large capacitor pack, and the precharge circuit, if I were to use an anti-spark connector (as150) between the bms (load+ terminal) and the capacitor pack and esc’s, would that serve to “bypass” the precharge circuit on the bms? For example, I would power-on the bms, then connect the bms to the caps&esc’s via as150…? Just curious, don’t want to damage anything on the pcb

So you are using caps for the ESC that are rated with a value in farads? Unless they are as big as a couple of times the size of your battery they are most likely nog suited for a high current buffering application that an ESC needs. Can you share a type number just to make sure?

https://emperformanceproducts.com/product/ripple-voltage-filter-energy-booster-cap-pack-23500-uf-12s-max-volt-8awg-wire/

These are the ones that I’m running EDIT: mine is 23500 uF version

Ah ok, looks like this might work without any changes straight on the output of the BMS.

This does not seem to be a cap(bank) that totals in the farad range, it is 23.5 mili farad :sweat_smile:.

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Lol, you are correct sir! Hahaha, I am an idiot. I forgot to check my symbols. That’s great news (except the me being an idiot part) thanks for the enlightening reply

I just received my DieBieMS today! I’m amped to get working on it.

One question, do the MOSFETs put off heat from both sides? The heatsink side is facing towards the board, but I’d like to add an additional external heatsink on the top side of the MOSFETs as shown.

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The heat dissipates from the “back” of the mosfet, meaning you’re heatsink in that Picture isnt very effective

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Ha! amped :sunglasses:.

Fancy looking!!

Well normally with this small style of skateboards I rally doubt that you would need any heat sinking.

But if you really want to than the best method is cooling from the bottom and then go to somewhere where you can get rid of the heat. That said, getting rid of any heat will always help, so from the top will help as well. Just make sure to keep som distance between the wire terminals.

One extra thought, be sure to take into account the space balance leads might take up.

cool design, I think your battery layout is a bit tricky to wire up though

Glad I asked!

lol I hadn’t realized I dropped a pun till now.

Is there a reason that most traditional BMS systems have huge heat sinks on them, and the DieBieMS doesnt? At first glance (from a non-electrical engineer perspective) is it that the DBMS takes a more efficient, ‘smarter’ approach to battery management vs the traditional chips?

Would sinking to the bottom of the PCB actually have any direct heat conduction path from the FETs? I don’t believe the copper goes from one side of the PCB to the other, correct?

Maybe I’m just completely over thinking this whole thing and don’t need to remove heat at all. I’ll be maxing my system out at probably 70A pull from the battery.

For sure! It’s going to have some weird wiring paths, but after like 4 iterations I think it’ll be the most space efficient setup with 26650 cells to avoid the case from hitting the ground on the flexy vanguard board.

Another question pertaining to building a battery pack with fuse wire to avoid fires.

IMO the only thing BMS can see is how voltage changes more rapidly when charging and discharging on that P group. Can be extrapolated out to how much total energy goes into (or out of) the pack before one P group hits cell high (or low) voltage cut-off.

Temperature sensors could also help, as that p group will likely run hotter if you’re running the pack at high loads.

I’m just thinking out loud though…

Hey, I received the BMS last friday and have build it into my board, it just fits :+1: (currently the load power cable and CAN wires are bundled in a mesh sleeve)

< LongPostWarning > A wiring diagram should really help, now I have searched the schematic and figured out pin 1 of the connectors with a multimeter

I have also been struggling a bit with the balance connection, The labeling C0+ and C0 on the connector layout is a bit misleading. after a few trails i found that C0 is the absolute minus of the balance chain.

Now i connected everything including CAN, it works, I can communicate with Metr.pro via the VESC and read cells. I connected the CAN_Enable directly to the CAN_5v but i can’t get it to power-on with a push. at some point I got it to charge but it won’t do that anymore. and also when powered the “smartled” blinks and goes off (the board stays powered)

Also remember to setup and store the settings cells & capacity with “config_write”

IMG_20180812_175612

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Push to start will be enabled in the new firmware. In the current firmware the BMS should only briefly turn on and go off immediately after pushing.

Yes I can imagine that the numbering is confusing, I have tried different schemes bus connecting balance wires keeps a frustrating job.

A manual writing will follow directly after the BMS Tool development

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thanks. if you are looking for beta testers, I’ll volunteer :wink:

Until the manual is ready, a pictorial guide how to connect the balance cable for the early adopters :smile:

(please correct me if i’m wrong)

diebiemsbalance

note: A Cell could consist of one or more parallel cells

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