Good morning, thanks for posting all your work so far. with regards to precharging the capacitors in the sofar inverter, was that required or is it something you felt was the correct thing to do? i intended using a seplos bms, and was told it has a precharge process built into it?
Have you got a wiring diagram on how the front panel is wired? Specifically the step down converters, whether you're using the negative from that to power the BMS, or direct from the battery and also the pre-charge resistor circuitry?
Hi, all the negatives are connected, the step down converter is not isolated, so has a common ground. The pre-charge is simply a button as resistor, which bypasses the circuit breaker
Another Stuart case. I see you working, in order to integrate the battery with your new inverter, in a DiY BMS emulation to Pylontech. It will be a great development, but I am curious to know if it will be modular, as is Pylontech, that is, if on a battery (16 cells) new batteries of the same size can be added to the system, connected in parallel and control them all together.
Really great work! I'm amazed you have got the DIY BMS to speak to the inverter - was that tricky to do? Where can I find more information about how you did this? Thanks for all your work.
Another excellent video 👍 Did you go for the Fogstar Grade B batteries? How long ago did you order - they currently show late December for availability.
Great video Stuart. It was hard to see but it looked like, when you connected the negative leads to the battery that you put the DIYBMS power supply lug on first followed by the main terminal lug. If that was the case, wouldn't it be better to put the main negative lug on to the cell terminal first and the DIYBMS power lug on second? It would probably give a better contact area for the main negative lug.
I'm searching for the rj45 connector thing, do you have a name or link to the one you've used ? Thanks any simple wireing diagram would be interesting, just a sketch on a piece of paper, or description. Thanks for sharing all this :) Your using PP 0.3mm sheet ?
I designed the cabinet using Free cad. Then sent the drawings to a local laser cutting company. They cut and bent the steel sheets and then I assembled
Brilliant, well done! Am I correct in understanding the inverter will only charge/receive max 60amps? So the inverter is the limiting factor not the BMS? Just thinking if you wanted to add more batteries. Sorry if this is a daft question, only started learning about all this recently.
You can push the ME3000SP a little harder than that, they'll do up to 70 amps discharge although since changing to 16-cell LiFePO4 mine seems to max out at 65 amps and a touch under 3.4kW output, I suspect it's due to the slightly higher battery voltage meaning it doesn't need 70 amps to max out its power rating.
@@AintBigAintClever thanks for the info. I'm still trying to decide which BMS for my build. I was reading some said even 200amps. Do other invertors support this high amps? Or realistically is this more a reliability rating? Thanks.
May I ask you a modest question. In the video, I see you put black insulating material between the cells. What kind of material, what is the full name. And one more question, more theoretical. Like you, many DIYers and battery assemblers put insulating materials between the cells. Could you explain the essence of this action? Why isolate the cases of lithium cells from each other? After all, the cell bodies and both the positive and negative terminals of the cells still do not have an electrical connection with each other. Don't you think that this is excessive caution? Have you seen cases where cells that are not isolated from each other harmed themselves or the user? Thanks
The cell cases are connected directly to one of the terminals depending on the type of cell. Adding insulation between the cells means you are not relying on that thin blue plastic wrap. The foam I used is 3mm EVA foam.
Good Video. Just a thought, surely you want to put your main negative cable on first and then the BMS lead on the connection for better contact? Probably not much in it, but thats what Ive been told from other videos.
Hi Stuart, what cable gauge did you use to connect inverter to battery? I have tried to use 50mm² and could not fit it in the Sofar ME3000. At the moment using 16mm² but it's getting warm at full power.
Keep in mind that each cells can expand .025”. 16X .025 = .480”. A fully charged assembly can see over 1,000 lbs of force if the cells were lightly clamped at a 30% state of charge. The maximum force on the cells should be no more than 650lbs. If the end plates start to bow with excessive pressure the end cells may experience internal damage. Stiff end plates with one end springed to maintain an ideal force of 550 to 650 is very important. Flexible buss bars should be considered to reduce terminal stress and loosing of the buss bar due to cell expansion and contraction. Protective insulation was a very important feature!
@@KoRWraith At 100% state of charge the cells can swell if not fixtures first. If they swell and not return to size at a low state of charge, it’s usually a bad idea to then fixture them after the fact. This usually happens more frequently to the 300ah size and much less to 270/280. On a hot day and full state of charge, a normal good unrestrained cells can bulge 1/16” per side and return to approximately where it originally was. If you had already top balanced your cells and they are full and your not planning on compressing but just want them contained in a rack, then I’d just very lightly snug the bolts (blue loctite) when the cells are at a full state of charge. This is what I’d recommend for solid buss bars because it’s set at maximum and at minimum charge there’d be a small gap between cells. If the cells in the video had already top balanced ,from what I could see on the video they did not appear swollen. When manufacturers state expected cycles, the fine print usually says “fixtured” (compressed) under a detailed maintained pressure (not unyielding rigid). The bottom line if it’s contained, understand the forces so it’s at least not crushed. There’s a video on TH-cam where in an RV has some sandwiched cells with two plates and four threaded rods and I can visually see the the last cells side kinked.
@@StuartPittaway I don’t remember where I first found it(on one of the many discussion on compression on diysolarforum ), but I actually have actually seen it myself; CATL 310ah cells from Eel (16) and Ninthsith(16) distributors in four compressed fixtures, 8 cells in each with a spring load at 550lbs. The spring loaded movable end plate moved 3/16” from a cool, 30% charge(new) to 100% charge on a 105 degree day. I marked the four boxes with a sharpie on day one and noticed it later. I actually posted a picture of it there months ago. Eve cells do it exactly the same. I’ve seen pictures of flimsy end plates that were that were distorted because the fixture/box was non moving/rigid, many are still in use without the owner knowing that the factory made battery is actually damaged but still functioning and not leaking…for a while anyway.
brilliant work stuart good stuff, i noticed the pylontech branch on your github, hopefully this will work with my mpp solar inverters :) ill have to give it a try
I'm doing a lot of changes in that branch at the moment, the pylontech emulation seems to be working well. I'm going to also try SMA protocol, which is the generic lithium setting on SOFAR and I think MPP solar
@@StuartPittaway Hi, I am building EPS32 DIY BMS + ESP NOW protocol + 8 A balance current with BUCKs, I am interested in idea, how to measure pressure in 4S packs, / LFP - Winston / or DOcan / that blue 280 Ah cells. I think, that 16S is very big chunk and for me it is better to manipulate with 4A packs. Also if 1. cell go to hell in 4S, it would be not so detrimental, as in 16S pack. Packs can be connected with DC fuse / PN00 - PN4 / or with heavy Cu bars + shunt. / 500 - 1000 A /. I am building system, when BMS + MPPTs + inverters / all DIY / communicate with each other, without cables or without router or switch. At one point there is gateway from ESP32 - ESP NOW to MQTT or RS485 or CAN. The BMS and MPPT will communicate with voice commands / statements if need + SD/uSD card can store data sampled or agregated at reasonable intervals / with respect to uSD capacity /. There can be IL9431 or SPI or I2C ink, oled or another TFT disp.
Hey Stuart I know you are working on your new all in one BMS. Have you thought of doing a split design for multiple packs. Example like batrium does with its watchmoncore and cell mate. Basically it’s a master slave system instead of the controller and and a bunch of cell monitors. You would only need one cell monitor per battery pack this that you can build a much larger battery pack than your current design. Just a thought.
@@StuartPittaway Nice looking forward to the new design. Will it handle more than 8 battery packs in parallel like your current design. Just curious why 20s and not stick with the current 16s design.
Please insulate your tools when they are close to the live battery. The wrench handle so close to battery terminals without insulation was scary to see.
Congratulations Stuart. Excellent work with an impeccable finish. I only have one question, how are you going to move the battery (I estimate that it weighs about 80kg). Apart from this joke that I hope you know how to fit. I am very interested in you explaining how the preload works. I don't have it in my system and I know that it means an extra risk for the inverter in the connections and disconnections of the battery, the internal capacitors of the inverter suffer (fortunately for a year and a half or so, I only disconnected the battery once.
I think it's at least 100kg now it's built, I would have to remove most of the cells to move it! The precharge circuit is very simple, I'll do a follow up video on the circuits aoon
@@StuartPittaway its like electric cars, only for the upper middle class and rich, all of this green tech and subsidizing of it have utterly raped the poor. Its just like Ukraine which people dont get a bunch of poor dudes forced by draft to fight a war they dont care about for the west, its this same story over nad over, everything at the expense of others, if it were real it would survive without the subsidies, we subsidize oil because its actually useful to do so thats why they keep cutting them, cant have those useful subsidies
![Balancing The Pack [Battery Build #7]](http://i.ytimg.com/vi/Nzn9ZbWnVf4/mqdefault.jpg)
![Balancing The Pack [Battery Build #7]](/img/tr.png)
![16S "all-in-one" release and installed [DIYBMS]](http://i.ytimg.com/vi/xVn2-6Keq2A/mqdefault.jpg)
A very well designed battery pack.
Cheers
That is brilliant Stuart. Neat, robust and functional.
Many thanks.
Nice box . Suggest to insulate the tools😊
Will do!
Wawoo brother your work is amazing 👏👏👏👍
Best regards from Philippines 🇵🇭
Thank you so much 😀
Good morning, thanks for posting all your work so far. with regards to precharging the capacitors in the sofar inverter, was that required or is it something you felt was the correct thing to do? i intended using a seplos bms, and was told it has a precharge process built into it?
I've not used the Seplos, but believe it does have a pre-charge function built into it.
Brilliant work ! Greetings from Germany
Thanks
Have you got a wiring diagram on how the front panel is wired? Specifically the step down converters, whether you're using the negative from that to power the BMS, or direct from the battery and also the pre-charge resistor circuitry?
Hi, all the negatives are connected, the step down converter is not isolated, so has a common ground.
The pre-charge is simply a button as resistor, which bypasses the circuit breaker
Another Stuart case.
I see you working, in order to integrate the battery with your new inverter, in a DiY BMS emulation to Pylontech. It will be a great development, but I am curious to know if it will be modular, as is Pylontech, that is, if on a battery (16 cells) new batteries of the same size can be added to the system, connected in parallel and control them all together.
The inverter/charger doesn't care what size the battery is, you can parallel multiple Pylontech units together so it will work the same.
@@StuartPittaway You are right, your system is already prepared so that you can put several parallels in it and manage them jointly. thanks Stuart
Looking good Stuart. Good effort.
Thanks 👍
8/10 quite a good video although a bit amateurish, I look forward to future videos.
Thanks for the feedback Darren - I'm not a videographer!
Really great work! I'm amazed you have got the DIY BMS to speak to the inverter - was that tricky to do? Where can I find more information about how you did this? Thanks for all your work.
All the source code is in GitHub. You might be interested in the victron integration I did many months ago.
Quite easy to do really
@@StuartPittaway Fantastic! Thanks very much.
Another excellent video 👍
Did you go for the Fogstar Grade B batteries?
How long ago did you order - they currently show late December for availability.
Yes I did. I had the late October delivery. They get a shipment every month - generally dozens of crates of the cells (thousands of cells!)
Excellent video and work, @Stuart Pittaway! Do you have specs on the enclosure?
Thank you. I designed the enclosure my self, it's cut out from 1.2mm sheet steel (laser cut and folded)
Thanks Stuart, looks good
Thanks Wayne
Oh, you tease. I'm looking forward to seeing the next BMS release. Does it by chance use a microcontroller that isn't out of stock? 🤣
Yes it does!
Great video Stuart. It was hard to see but it looked like, when you connected the negative leads to the battery that you put the DIYBMS power supply lug on first followed by the main terminal lug. If that was the case, wouldn't it be better to put the main negative lug on to the cell terminal first and the DIYBMS power lug on second? It would probably give a better contact area for the main negative lug.
I should probably read the comments first. Someone else already raised this with you. Ignore me too 😁
I probably did do that on the video, but since corrected. I've disconnected those cables so many times over the past few days!
I'm searching for the rj45 connector thing, do you have a name or link to the one you've used ? Thanks any simple wireing diagram would be interesting, just a sketch on a piece of paper, or description. Thanks for sharing all this :) Your using PP 0.3mm sheet ?
The PP is 3mm thick.
These are the RJ45 connectors I used (keystone jacks) amzn.to/3Y7m6mp
Could you explain the process and who you send this cabinet to be built?
I designed the cabinet using Free cad. Then sent the drawings to a local laser cutting company. They cut and bent the steel sheets and then I assembled
Brilliant, well done! Am I correct in understanding the inverter will only charge/receive max 60amps? So the inverter is the limiting factor not the BMS? Just thinking if you wanted to add more batteries. Sorry if this is a daft question, only started learning about all this recently.
You can push the ME3000SP a little harder than that, they'll do up to 70 amps discharge although since changing to 16-cell LiFePO4 mine seems to max out at 65 amps and a touch under 3.4kW output, I suspect it's due to the slightly higher battery voltage meaning it doesn't need 70 amps to max out its power rating.
@@AintBigAintClever thanks for the info. I'm still trying to decide which BMS for my build. I was reading some said even 200amps. Do other invertors support this high amps? Or realistically is this more a reliability rating? Thanks.
I've had 65amps out of it. What firmware version are you running? I'm on V3.00 at the moment, running G98 country setting
@@StuartPittaway 3.16 on mine, I've just checked and confirmed it's running on G99 (option 009). I must change my Enphase rig to G99 at some point. :)
May I ask you a modest question. In the video, I see you put black insulating material between the cells. What kind of material, what is the full name. And one more question, more theoretical. Like you, many DIYers and battery assemblers put insulating materials between the cells. Could you explain the essence of this action? Why isolate the cases of lithium cells from each other? After all, the cell bodies and both the positive and negative terminals of the cells still do not have an electrical connection with each other. Don't you think that this is excessive caution? Have you seen cases where cells that are not isolated from each other harmed themselves or the user? Thanks
The cell cases are connected directly to one of the terminals depending on the type of cell.
Adding insulation between the cells means you are not relying on that thin blue plastic wrap.
The foam I used is 3mm EVA foam.
Good Video. Just a thought, surely you want to put your main negative cable on first and then the BMS lead on the connection for better contact? Probably not much in it, but thats what Ive been told from other videos.
Edit: I just saw later on in the video you have done the above! ignore me!
Thanks for watching
Hi Stuart, what cable gauge did you use to connect inverter to battery? I have tried to use 50mm² and could not fit it in the Sofar ME3000.
At the moment using 16mm² but it's getting warm at full power.
I'm using 25mm cable, suitable up to 150Amps
Very nice build Stuart!
I was wongering what value resistor are you using for pre-charge?
47 ohm, 100watt resistor
Keep in mind that each cells can expand .025”. 16X .025 = .480”. A fully charged assembly can see over 1,000 lbs of force if the cells were lightly clamped at a 30% state of charge. The maximum force on the cells should be no more than 650lbs. If the end plates start to bow with excessive pressure the end cells may experience internal damage. Stiff end plates with one end springed to maintain an ideal force of 550 to 650 is very important. Flexible buss bars should be considered to reduce terminal stress and loosing of the buss bar due to cell expansion and contraction. Protective insulation was a very important feature!
Better to compress at 100% SOC or somewhere in between?
@@KoRWraith
At 100% state of charge the cells can swell if not fixtures first. If they swell and not return to size at a low state of charge, it’s usually a bad idea to then fixture them after the fact. This usually happens more frequently to the 300ah size and much less to 270/280. On a hot day and full state of charge, a normal good unrestrained cells can bulge 1/16” per side and return to approximately where it originally was. If you had already top balanced your cells and they are full and your not planning on compressing but just want them contained in a rack, then I’d just very lightly snug the bolts (blue loctite) when the cells are at a full state of charge. This is what I’d recommend for solid buss bars because it’s set at maximum and at minimum charge there’d be a small gap between cells. If the cells in the video had already top balanced ,from what I could see on the video they did not appear swollen. When manufacturers state expected cycles, the fine print usually says “fixtured” (compressed) under a detailed maintained pressure (not unyielding rigid). The bottom line if it’s contained, understand the forces so it’s at least not crushed. There’s a video on TH-cam where in an RV has some sandwiched cells with two plates and four threaded rods and I can visually see the the last cells side kinked.
Thanks for the info, I'll take a look and do some measurements
Where did the expansion measurement come from? I'm not able to see that in the cell data sheets.
@@StuartPittaway
I don’t remember where I first found it(on one of the many discussion on compression on diysolarforum ), but I actually have actually seen it myself; CATL 310ah cells from Eel (16) and Ninthsith(16) distributors in four compressed fixtures, 8 cells in each with a spring load at 550lbs. The spring loaded movable end plate moved 3/16” from a cool, 30% charge(new) to 100% charge on a 105 degree day. I marked the four boxes with a sharpie on day one and noticed it later. I actually posted a picture of it there months ago. Eve cells do it exactly the same. I’ve seen pictures of flimsy end plates that were that were distorted because the fixture/box was non moving/rigid, many are still in use without the owner knowing that the factory made battery is actually damaged but still functioning and not leaking…for a while anyway.
brilliant work stuart good stuff, i noticed the pylontech branch on your github, hopefully this will work with my mpp solar inverters :) ill have to give it a try
I'm doing a lot of changes in that branch at the moment, the pylontech emulation seems to be working well.
I'm going to also try SMA protocol, which is the generic lithium setting on SOFAR and I think MPP solar
Hi, can u monitor pressure at all cell at diff. Temps ? THANX
I'm not measuring pressure on the cells - just temperatures
@@StuartPittaway Hi, I am building EPS32 DIY BMS + ESP NOW protocol + 8 A balance current with BUCKs, I am interested in idea, how to measure pressure in 4S packs, / LFP - Winston / or DOcan / that blue 280 Ah cells. I think, that 16S is very big chunk and for me it is better to manipulate with 4A packs. Also if 1. cell go to hell in 4S, it would be not so detrimental, as in 16S pack. Packs can be connected with DC fuse / PN00 - PN4 / or with heavy Cu bars + shunt. / 500 - 1000 A /. I am building system, when BMS + MPPTs + inverters / all DIY / communicate with each other, without cables or without router or switch. At one point there is gateway from ESP32 - ESP NOW to MQTT or RS485 or CAN. The BMS and MPPT will communicate with voice commands / statements if need + SD/uSD card can store data sampled or agregated at reasonable intervals / with respect to uSD capacity /. There can be IL9431 or SPI or I2C ink, oled or another TFT disp.
this absolute brilliant m8
Thanks
A multimeter from the days when Maplin were cheap.
Think this old thing was about £50, big money back then!!
Shame it's permanent 0.02V out!!
@@StuartPittaway bought back when you couldn't care less about a difference of twenty thousandths of a volt :)
@@AintBigAintClever ha! Very true.
Hey Stuart I know you are working on your new all in one BMS. Have you thought of doing a split design for multiple packs. Example like batrium does with its watchmoncore and cell mate. Basically it’s a master slave system instead of the controller and and a bunch of cell monitors. You would only need one cell monitor per battery pack this that you can build a much larger battery pack than your current design. Just a thought.
Thats sort of what I'm going to start with - a single modules which can look after up to 20S cells, and connects back to the existing controller.
@@StuartPittaway Nice looking forward to the new design. Will it handle more than 8 battery packs in parallel like your current design. Just curious why 20s and not stick with the current 16s design.
@@carlospereira9838 it's up to 20S as that's what the chip supports, so suitable for 8S to 20S
@@StuartPittaway OK thanks for the reply. Looking forward to the new design
Please insulate your tools when they are close to the live battery. The wrench handle so close to battery terminals without insulation was scary to see.
I know! I was being very careful, but as you say, mistakes can happen.
Congratulations Stuart.
Excellent work with an impeccable finish. I only have one question, how are you going to move the battery (I estimate that it weighs about 80kg). Apart from this joke that I hope you know how to fit. I am very interested in you explaining how the preload works. I don't have it in my system and I know that it means an extra risk for the inverter in the connections and disconnections of the battery, the internal capacitors of the inverter suffer (fortunately for a year and a half or so, I only disconnected the battery once.
I think it's at least 100kg now it's built, I would have to remove most of the cells to move it!
The precharge circuit is very simple, I'll do a follow up video on the circuits aoon
can the BMS do 7s or just 16s
Yes, 7s or more is fine.
Hello! Can you name the patch panel RJ45?
I can't find the exact one I brought, but search for panel mount RJ45 on google and there are lots similar.
Excelente!
Thanks
L I K E 👍👍👍👍👍👍👍 ❤🧡 💛🧡❤ 🤩🤩🤩🤩🤩
Thanks
I honestly dont know how people afford all of this
It does add up, however the savings on monthly energy bills can offset that fairly quickly, I think my payback would be less than 2 years.
@@StuartPittaway its like electric cars, only for the upper middle class and rich, all of this green tech and subsidizing of it have utterly raped the poor. Its just like Ukraine which people dont get a bunch of poor dudes forced by draft to fight a war they dont care about for the west, its this same story over nad over, everything at the expense of others, if it were real it would survive without the subsidies, we subsidize oil because its actually useful to do so thats why they keep cutting them, cant have those useful subsidies