Open source BMS for 48V to 400V lithium-ion battery pack

[Ohms_Cousin]

Would be really great if we could get hold of the IC needed for 15s/18s. How difficult are they to procure? How big of a change of setup is it to the PCB/system to change over to the better IC ?

If I understand this correctly, the PCB's are made from a Gerber file which is sent to a place that fab PCB's?

Further, one orders the components from the BOM supplied to populate the PCB - how does one get these parts fitted/soldered to the PCB? Is there a place that does this as a commercial service for small runs?

 

[john61ct]

No, just learn to solder

practice on cheap / scrap stuff first

 

[Ohms_Cousin]

hmm, its going to be quite the adventure then. I would think it takes a lot of skill to solder parts to a PCB and get a nice job. Well, not to worry, no pain - no gain.

 

[ENNOID]

Would be really great if we could get hold of the IC needed for 15s/18s. How difficult are they to procure? How big of a change of setup is it to the PCB/system to change over to the better IC ?

Other slave IC will come in the future. There is no driver for those right now. So LTC6813/6812 are still not supported.

Further, one orders the components from the BOM supplied to populate the PCB - how does one get these parts fitted/soldered to the PCB? Is there a place that does this as a commercial service for small runs?

Hand soldering is ok for initial prototyping, but one must be very careful for assembling by hand such complex PCB, the risk of bad connection & mistake is high and a lot of time is needed to troubleshoot each mistake. Also, you will end up paying a lot more for individual parts when ordering such small quantity on mouser, newark or digikey. Some still prefer to do it themselves because they enjoy doing it, but I'm not one of those.

Most fab for PCB offer PCB assembly services. They use pick & place machines, have huge discount on parts & use industrial reflow ovens & have quality control.

For the assembled PCBs I'm selling on my website, I'm dealing with seeedstudio for PCB & assembly. They are good & cheap for small to medium batch production. JLCPCB is another option and they should offer assembly service soon according to their website

 

[Ohms_Cousin]

Most fab for PCB offer PCB assembly services. They use pick & place machines, have huge discount on parts & use industrial reflow ovens & have quality control.

This makes far more sense.

 

[Ohms_Cousin]

Ennoid,

Any further updates to this project?

 

[ENNOID]

First small production batch for ENNOID-BMS has been shipped from china this morning & I should be able to send PCB to customers.

I'm spending most of my time now on improving the production process of my 12S10P battery modules integrated with ENNOID-BMS.
Fire retardant ABS is hard to 3dprint & I'm now looking for a bigger & more powerful 3dprinter with a 150C heatbed. This would allow me to build bigger ABS battery modules without restrictions on size.

 

[Ohms_Cousin]

Your project has plunged me into the world of 3D printers ! I am very keen to print battery cases and make up battery packs using your system.

Having spent the last week using most available hours to study 3D printing, I am getting up to speed on 3D printing. Have you considered NylonX filament ? https://www.matterhackers.com/store/l/nylonx-carbon-fiber-nylon-filament-1.75mm/sk/MD5LDGS7

It sounds like the NylonX prints very very nicely and is very hard/stiff/strong/tough. It is a Nylon/Carbon Fiber composite material.

I have also become very interested in this printer.... https://www.youtube.com/watch?v=84W9AH8-vis (Modix Big 60)

We really need the updated IC's - any idea of when they may be available (along with code to drive them) ? 16S/Bigger the Better P would be ideal for me (LiFePO4 chemistry 18650's).

Any progress on the chargers ?

 

[Ohms_Cousin]

3dprinter with a 150C heatbed.

This just jumped out at me.....150c heatbed ??? Where is such a printer ? Highest I have seen is 120c but enclosed.

 

[ENNOID]

All materials can be used for the plastic case, nylon is one of the sturdiest, but also quite hard to print & expensive. I actually started with PLA, then moved to PETG, & now using a special ABS with fire retardant additive. (forget about conductive materials, your nylon with carbon might be conductive...)

Some rare 3dprinter can go up to 150C for the heatbed, large ABS prints requires higher heatbed temp for preventing any warping. I have some warping issues right now with ABS filament...

We really need the updated IC's - any idea of when they may be available (along with code to drive them) ? 16S/Bigger the Better P would be ideal for me (LiFePO4 chemistry 18650's).

New LTC6813 (18S) & LTC6812 (15S) are still hard to source, I prefer to wait a bit more. I spent some time recently comparing the new IC datasheet to the actual LTC6811(12S). They are almost software compatible, the code shouldn't be hard to adapt. If I would create a slave board with LTC6813, would you be willing to buy me some? That would help me to give a push on that.

Actually, LTC6811 can do 16S, you just need 2 Slave boards, each monitoring 8 cells ... One could get a large 3Dprinter, print a 16S module and put 2 slave boards on top. Not as optimal, but would do the job. Other solution, 2 small 8S modules with a slave on each.

I have also become very interested in this printer.... https://www.youtube.com/watch?v=84W9AH8-vis (Modix Big 60)

I looked at it last week. I'm not convinced. Heatbed not going above 120C & huge Z axis travel is not really required for my prints

I'm thinking to adapt this CNC router with a 3Dprinting head+custom heatbed+enclosure & maybe doing some other stuff with it like alu wire fusing:
https://openbuildspartstore.com/lead-cnc-1010-40-x-40-1/

 

[Ohms_Cousin]

(forget about conductive materials, your nylon with carbon might be conductive...)

Yes I thought about that and checked - it is not conductive.

There is another filament that sounds interesting - good reviews at least. Its a Carbon Fiber Polycarbonate composite. Sounds to be the best of both worlds and is a little more economical - https://www.amazon.com/PRILINE-Polycarbonate-Filament-Dimensional-Accuracy/dp/B074DS3986/ref=cm_cr_arp_d_product_top?ie=UTF8 - how much filament does a case use ?

I agree about the Modix 60 - it only goes to a 120C heatbed. I could use the bigger size for other things as well, but that is specific to me. The only printer I am seeing that goes to a much hotter heat bed is this one https://www.3dxtech.com/gearbox-ht-printer/, but its also a crazy crazy price - not in my league anyway. Its heat bed goes to 200C ! But its circa 50K ! so not realistic I think.

If I would create a slave board with LTC6813, would you be willing to buy me some? That would help me to give a push on that.

Yes I may be very interested in this arrangement. I emailed you the other week and you emailed me back about all this. So lets carry on that conversation via email.

I am very keen to get involved in making these packs/system for my needs.

 

[Ohms_Cousin]

I'm thinking to adapt this CNC router with a 3Dprinting head+custom heatbed+enclosure & maybe doing some other stuff with it like alu wire fusing:
https://openbuildspartstore.com/lead-cnc-1010-40-x-40-1/

That sounds pretty hardcore ! Can you do it ?

 

[Ohms_Cousin]

https://www.amazon.com/PRILINE-Polycarbonate-Filament-Dimensional-Accuracy/dp/B074DS3986/ref=cm_cr_arp_d_product_top?ie=UTF8

This stuff sounds like the business !

September 9, 2018
Material: Carbon Fiber PolycarbonateVerified Purchase
Update 1: I'm currently on my second spool of this stuff and continue to be extremely impress with the results. Only issue is that this stuff sticks REALLY REALLY well to PEI. Protip: Hairspray on glass surface works wonders.

I have been printing nearly exclusively with ABS for about 5-6 years, so I know my share of printing pains (cracking, warping, adhesion, etc) since I always print functional parts and need the strength. PLA just wasn't going to cut it.

I decided to spice up my printing life by venturing to the more exotic filaments to print parts for a new rail-based CoreXY printer. I decided to try this filament since it had such great reviews.

I must say, WOW!!! This filament is amazing, absolutely amazing. The prints are strong as hell, dimensionally accurate (since it doesn't warp like ABS), and just looks fantastic! No more having to mess with increasing the models by 0.5-1% to account for shrinkage of ABS.

After a lot of trial and error, I think I have things pretty dialed in. Pictures are attached. Print settings as follows:
Printer: Heavily modified all-metal Rostock 2 Delta
Software: Simplify3D
Retraction distance: 2.5mm
Extra restart distance: -0.2mm
Retraction lift: 1.0mm
Retraction speed: 80mm/s
Hotend Temp: 235c (genuine "Floating" E3D Titan Extruder with Volcano hotend and hardened 0.4mm steel nozzle
Heated bed Temp: 90c
Printing speed: 60mm/s
Layer height: 0.2mm (0.1mm looks a little better, but takes too damn long)

 

[ENNOID]

Just dropping this here for the ones interested.

Other slaves board 15S & 18S will, one day maybe not too far away, be supported by ENNOID-BMS :

 

[ENNOID]

New development on the Master board as well.

I decided to simplify the design a bit, so better integration with contactors & current sensor on master V2. Fewer connections are required. Now with integrated precharge resistors. HV sensing for load & pack voltage is done directly from the contactors terminals. The 500A-0.1mOhm current sensor is mounted below the master board, soldered directly to it & everything bolted on main 500A contactors.



Wiring diagram is also far simpler:

Distances for isolation have been increased as well for high voltage operation.

Code for firmware & configuration tool have improved a lot recently with the app V0.31 now simplified and many new options.

Beta tester required. PM me in private if you want to try this out.

 

[c10yas]

Why do you have 2 fuses? Two contactors and one fuse should be more than sufficient right? Also, how much current can flow through the PCB? Are you going solder bus bars to the bottom of the master board? Also are those the ev100 or ev200 contactors?

Sent from my XT1710-02 using Tapatalk

 

[ENNOID]

no current is going through the PCB, the shunt 0.1mohm busbar is below the pcb and carry all the current. The signal only is going through the PCB to an isolated amplifier amc1302.

Fuses are only on the drawing and outside of ENNOID-BMS.. user can remove them if not needed. Two evc500/ev200 contactor are better for safety I think, they isolate the pack completely in case of problem...
Despite this only one contactor can be used if the user add an external switch for precharging.

EVC500 is cheaper than all other options

 

[c10yas]

Is it possible to allow using the ev100? It's a cheaper relay and can do 225A for up to 6mins with no issues. This is more than enough for most applications I can think of and is much cheaper

For the precharge circuit. Look at high voltage reed relays like coto-9104 that can easily conduct enough current to precharge a capacitor. Also consider using a smaller resistor for precharge that isn't focussed on dissipating heat so much as just absorbing it. Precharge is generally only a few seconds long and there's no point getting a resistor that can dissipate the peak precharge power continuously

 

[ENNOID]

I'm aware of those EV100, but EVC500 can be bought brand new for 49.99$ each on ebay and can do 500A continuous and is not way bigger than ev100.Hard to beat at this price I think.

I will look at those toco relays

 

[john61ct]

Is the ampacity rating for a contactor like EVC-500 higher or lower when the load being interrupted is at lower voltage?

Say 3-5V vs 12V ?

 

[c10yas]

Is the ampacity rating for a contactor like EVC-500 higher or lower when the load being interrupted is at lower voltage?

Say 3-5V vs 12V ?

DC Voltage/Current are independent of each other in this context. 500A at anything below the EVC500's rated voltage is fine..... Unless you're talking about AC.

Sent from my XT1710-02 using Tapatalk

 

[john61ct]

Thanks. And no all just DC

I have seen quality contactors that spec a minimum voltage, I inferred the rating would be different in the sub-5V range.

 

[c10yas]

Minimum coil voltages definitely exist but minimum terminal voltage definitely isn't a thing. Unless they just mean to specify the voltage drop across the contactor terminals at maximum current

Sent from my XT1710-02 using Tapatalk

 

[john61ct]

No, was contactor / power current nothing to do with coil / signalling.

I'll just take the ampacity rating as good for lower volts then, building in headroom anyway

 

[ENNOID]

Penthouse box V2:



This box contains:
- ENNOID-BMS master board V2
- 500A Current sensor
- 12V 5A output power supply from HV Pack (48V to 400V input)
- Two main EVC500 contactors (500A, 400+VDC capable)
- Power button
- LCD screen which shows the SOC, voltage, current, Max temp, Min Temp, Avg temp in real time

Here is how battery modules can be connected with ENNOID-BMS Penthouse:



Software is ready with ENNOID-BMS tool app.
Firmware is also ready & functional with master V2.
Testing V2 right now under heavy loads & will test with LTC6812 slaves next week...

Exciting time for ENNOID-BMS!