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Disclaimer: I mention vendors below and use them as an example and as reference. This should not be considered an endorsement of said vendors! In light of Will's recent video and some of the comments both there and on the forum, I thought it would be a good idea to do a full cost analysis of a...

I'm writing this post since it seems there is a lot of confusion (especially in the comment section of a certain youtuber in Australia) on why both MOSFETs in a typical single port BMS are controlled individually and why/how this works when they're in the same series circuit. It will hopefully...

Let me know when I can buy battery packs off-the-shelf, insulated and heated, with easy maintenance for anywhere near the price I make my own. There will always be room for DIY since it's not just about price: it's about knowing how the system works, being able to fix it when it breaks with...

I thought this deserved some attention: the forum just reached 100k users! Well done @Will Prowse and everyone else contributing to making this place excellent!

Ok, I need to get this off my chest. It's been bugging me for some time now, and a recent YT video made it worse. Terminology matters. A lot. In engineering, words have specific meanings and these terms help us communicate ideas and concepts correctly. When people start assigning other meanings...

Probably not really feasible, but I'd like to see off-grid set-ups from around the world, where they all have their unique challenges and solutions.

Bought 16 more MB31 cells, which will bring the total battery size to 120kWh.

My braided bus bars:

Keeping in line with the whole low-cost solar system, building my own braided bus bars, etc. I thought I would see what it takes to build a low-cost ground mount for those 500W 96 cell panels (1310mm x 1956mm). My goals were to make the whole thing simple to build, with minimal tools and simple...

This is a recalculation based on the situation today, of what I did last year. Disclaimer: I mention vendors below and use them as an example and as reference. This should not be considered an endorsement of said vendors! Let's start again with leveling the playing field. The EG4 is a 5kWh...

So, instead of just doing the usual and buying some Victron and Batrium equipment and calling it a day, I went shopping on Alibaba and Aliexpress to see if I could build my entire 32x280Ah and 10kW solar panels system for under 10K Euro, keeping in mind the power and charge requirements - so not...

Part of that means being able to guide people to the stuff they need. This automatically means pointing out where to get them. To be honest, I'd rather have a vendor engage on the forum and have a two way communication in the open, than some he said/she said over Alibaba. Much easier to call out...

So after running my 32 EVE cells for the past 6 months I decided to pull my weakest cell and do a capacity test. Tester used was a CBA IV, at 20A discharge (can not really do a .2C test right now). Result: Ignore the bump at the 50Ah mark, I tightened the nuts better around that time - but...

Let's keep politics out of this discussion please - focus on the potential impacts, prices, etc.

If she did not have that fuse, this would have been a lot worse... Definitely worth the cost of the Class T fuse.

Some of us on this forum took a risk several years ago when we first bought these cells, before anyone on YT even knew about them. I did that because a) I was looking for something else besides Winston cells and b) If these cells worked, they would be able to get me the amount of storage I...

Don't. Part of DIY is to learn to make better systems. Can't learn without mistakes, and sometimes even catastrophic ones. You know the saying in engineering: 'Every safety rule and regulation is written in blood'. In this field, some of the rules have yet to be written, which is why it's...

Sometimes (especially these days now that we see the sun again) I forget I'm on solar. I rarely check on it at all - I've got other things to do with my time.

Until I see some evidence to the contrary, I do not believe this is due to a LFP explosion, off-gassing or otherwise.

I'd rather people shoot down bad advice with facts and evidence. That way, people can learn why it's bad advice to begin with.

Most of the time, someone (me included) will make a post in the thread pointing out the correct units. Nuking the post is not useful, but corrections made in responses help educate people.

Ok, this has been grinding my gears to the point where I'm annoyed with it, so I just wanted to write it down here. I see statements like this all over the net when it comes to cell capacity testing: - "you need to divide the Wh reading by the nominal voltage of 3.2V to get the real Ah...

I'm posting this in a thread here since it might be useful for people. Please keep in mind that the below calculator contains bugs and doesn't do error checking - it's literally been 5 minutes to put together. Ok, so what does it do? It calculates the maximum open circuit voltage you would see...

It happens. We tend to let it happen. The reasoning is that if there are threads with specific issues/questions, they likely get answered for OP in the first or second page or so. However, threads that then go off-topic tend to become interesting discussions (well, not always, but I digress...)...

Another 36 solar panels, 410W, for 99 Euro each.

I was looking for a way to detect bad cell terminal connections in multiple parallel battery packs. I found out that this is actually very easy to spot if you graph the cell delta on the packs. I introduced a bad connection in one of my packs and let it run for a day. It went through charge and...

Ok, update time. Finally had some time to have a look at the new BMS. The new one on the right, old one on the left. They're both 100A versions to keep the comparison easier. The port to the right of the GPS/RS485 label is the display port. As Dave Jones would say: "Don't turn it on. Take it...

First test version of my flexible bus bars, with nickel plated contacts. Nickel plating was done with nickel acetate, made with vinegar and a pure nickel bar used for electroplating.

Yeah, the first time you deal with those size of panels, you go: what the F**k did I get myself into...

So, the thing is... after this is one is installed I won't have space for more... which means I really need to get started on my 1MWh container soon.

Something can always go wrong, especially with high currents. Contacts can fuse, FETs may fail, etc. Personally, I trust a class T fuse much more in these situations compared to a breaker or the BMS ability to shut it all off.

I think most here on the forum know I have been hammering on the use of Class T fuses since forever (and at times received push-back). I also talked to Victron (and other) reps at several occasions about using class T fuses (or at least similar, like BS88 etc), and did the same with BMS...

Last night: In this last picture, Jupiter can be seen in the middle. Below and to the right of Jupiter is Aldebaran (in the 'band' of the aurora). The Pleiades are also visible (to the top and right).

As some of you may know, I'm in the process of moving my batteries into a new enclosure. Reasons: it's more organized, space is better optimized, and I can add more batteries more easily later if needed. This is the first time I took these apart since I built them somewhere early 2020. I bought...

What do copper pipes say when they leave? Cu later!

Spam Bots pushing whatever they can trying to overwhelm a system. One of the issues is that the posts all started a new thread, and that this is harder to deal with to just designate the user as a spammer and delete all the posts. It's something that should be addressed in an update to the forum...

Trust me, I know what I'm doing :)

You will always need more batteries and panels ;)

These are the merits and pitfalls of DIY. Some of us will take the risks. I was one of the first to use the original style JK in production, especially with multiple in parallel. I like doing this - I like smoke and bleeding edge shenanigans :) I take stuff apart when they break, analyse...

I'm building a high voltage version to run in parallel with a similar sized LFP version. This is for a research data center; I'll share data once we have some. We're also running some cycle tests at different temperatures on Sodium cells - those results should be in any day now.

We don't know anything, that's why we're 17 pages into speculation.

So, time for an update again! - Solar panels and charge controllers No problems what so ever. I bought some other panels in the mean time (36 x 410W Astronergy panels as mentioned in the post above, of which I kept 16 myself). This brings the total to 16.5kWp installed. Those additional panels...

Same here with AWG. Sure, let's indicate bigger conductors with smaller numbers. Oh no, we reached 0, let's go 00 and 000 and 0000. Yeah, makes sense 👌

You also have this thing called inverter loading ratio: So while you can't use the max power your array would be capable of and your lose this (clipping), the overall energy output increases due to higher average generation during the day.

We're not usually editing posts, but for the safety of the poster I've removed email and home addresses from the initial post and all replies.

Almost like there is a world wide inflation going on or something... with high interest rates as a result, and people not buying stuff (as intended) to lower consumption. And as a side effect, prices drop due to less demand or something. That said, please someone find me a 3000VA inverter that...

I use both. I just don't have enough energy in winter, and I enjoy cooking on gas. Best of all is the outdoor kitchen using wood though...

So after running this system for a little over a year now, I thought it would be a good idea to give a more in-depth status report. Let's go over all the components of the system. - Solar panels I am extremely happy to have gone with these large 500W ones. Not only do they perform as they are...

You joke, but having 100kWh at home even just 10 years ago was almost unimaginable...

... than to go into discussion with SFK on Andy's YT comment section. For context, the issue is that the JK (new one) resets its values after x amount of time un-powered. This is a bug, obviously, and the reset values of 4.2V per cell are very bad for LFP. So SFK commented under the video...

And keep in mind that mine is a log house, with insulation mostly in the roof (like yours) and the floor, plus triple glazing with Argon. I have huge windows, and of course, log is just that - a thick piece of wood. Being surrounded by forest means I have ample fuel to keep me warm in winter. In...

At least it will be in about 20 minutes where I am. Wishing you all the best for 2020!

One of the reasons I like the one BMS per pack is that I can put a failsafe in the BMS: if my max power draw is 6kW (the inverter limit), and I have 7 banks in parallel, that means I can put the BMS limit at 20A discharge per pack or so. Anything over that and the pack gets disconnected. The...

off-grid, 100kWh Edit 2025: 120kWh now.

Over here you don't need a permit for a ground mount, only a notification. No engineering drawings, maybe a location drawing. The law basically says: "Don't make dramatic changes to the landscape, and don't annoy your neighbors". It was specifically changed in the law to make solar ground mounts...

Here we go again - time to do a another calculation. (previous posts here, here, here, and here). I will go with both cheapest cells available (B-grade) and A-grade cells in Europe. At some point I'll do an Alibaba version again (and a US version if I find the time) but prices are very similar...

So... I've just bought a pallet of 36 x 410W Astronergy panels. At 0.275 Euro/Watt delivered it was too good not to. My plan is to split the batch with family, and expand my system in anticipation of an EV. Can't wait :)

I've had numerous requests over the past year or two asking for more details regarding my set-up, how I built my place, what the requirements are for off-grid living in a cold climate, building materials, etc. Several people asked me to start a YT channel... I don't really have the time for...

The issue is that aluminium oxide is non conductive. Copper oxide is conductive. One must use extra precautions when using aluminium, which are a non-issue with e.g. nickel plated copper.

Moved to chit-chat. Still: welcome to the forum! Enjoy your stay and don't let things bother you too much.

I don't want to bother with initial top balancing cells. I want to put them together, slap the BMS on it, and have it balance them in operation in a matter of days. It takes forever to do that with 300Ah cells and a passive balancer.

Alcohol is an option.

kWh - ftfy ;)

In case anyone is interested, I wrote down the goals and results in a longer form on my blog. The first part details the requirements, power audit, goals and some history. The second part deals with the actual components, costs, reasons...

It seems that cell prices are starting to really drop - for those of us in Europe: https://www.nkon.nl/rechargeable/lifepo4/prismatisch/envision-ess-4lh3l7-280ah-lifepo4-3-2v-b-grade.html Under 70 Euro per cell if you buy 16. Granted, they're not in stock right now, but I'm hoping this is a...

Almost time to expand to 100kWh :)

You know my thing with building a cheap 10kW system, right? Guess what I never, ever cheap out on: Class T fuses. I've witnessed tons of LiFePO4 shorts, and frankly, they're scary. I've also seen ANL fuses just sit there in a short, arcing, heating up and melting the plastic holder they're in...

You can take LFP down to 0% (2.5V per cell) and it won't be an issue. Cycle life is determined between 0% and 100% by the manufacturer. Could you get more cycles if you don't go to 0%, maybe, but calendar aging will be more of an issue. We're talking 4000 cycles 0% - 100% to start with.

Time to do a another calculation again. (previous posts here, here and here) - but this time, I will go cheap (but with cells available in Europe - I'll do an international Alibaba version at some point). Disclaimer, as usual: I mention vendors below and use them as an example and as reference...

Ever consider it's because of the policies of your government that your grid has issues and prices are going up? Here in Finland, electricity prices have been going down - and that's because of renewables (especially wind and hydro) and nuclear. We're already seeing spot prices that are close to...

Nonsense. Let me try to debunk some of those points. The majority of the energy from the sun is in the visible spectrum and solar panels are tuned to this. Here is a graphic: As you can see, there is very little energy in the UV (and IR) range and solar cells are tuned for this. There is a...

Some of mine are now in their 6th year of 24/7 use without issues. I'll let you know in a few years.

Indefinitely. I've got spare parts for everything, run multiple inverters and charge controllers (so even if one goes down, it won't bring the system down) and can do component level repair on everything. That said, I can also keep the place running without power at all even in dead of...

An Eddy is something that is also used in fluid dynamics, but has a specific meaning there too - the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. Different field, same term - no problem. The main problem is calling something an "Eddy current"...

I know there is a lot of frustration and emotions run high, but do keep things civil please.

Solar panels also finally arrived:

My wood splitter and chain saw. Fully electric, no fuel to deal with, processing all my wood for winter during times I have excess solar in spring/summer/autumn.

Temperature is the real issue, and kills LiFePO4 faster than anything else. You can be at 100% SoC and 0C and you will have far, far less impact than being at 50% SoC at 30C for the same amount of time. That's why I mention that SoC isn't a huge deal compared to temperature. Some datapoints from...

That's cheating :)

I would like to clarify one thing: I am not saying that Ray or Docan is misleading anyone on purpose. I'm a happy customer of Docan myself. The big issue with raw cells at the moment is the terminology. "Grade A" doesn't mean anything. Docan uses it, Luyuan uses it, and everyone else uses it...

Send some of that over here. Our winter is too mild this year...

Ok, yeah, that'll do it... Change the wife, it's the cheapest option :)

Already installed. So are several other systems. It's a balancing act... You wouldn't believe how many are already stopped before you notice. It's one of the things a forum with close to 100k users just has to deal with, and I think we're doing ok for the moment. There are always a few that get...

This is probably the last day of having a chance to get my batteries to 100% before winter, so I took it to 3.5V per cell. Biggest deviation was around 30mV which (with a 0.6A balancer) was resolved within a few minutes. No runners, no issues - these are the original 280Ah cells, manufactured in...

I'm moving this thread the the 'up in smoke' forum, now that we have the reason it went wrong. It can hopefully help others as well...

@Nami : wouldn't it be easier to just release the software as open source so we can pool resources? There really isn't anything secret in the code after all. JK could release official versions, the community could build their own for certain edge cases, implement protocols they want, etc. both...

More pictures: Got around to putting some gravel in place. Still a bit more to go: L-brackets to hold the panels to the beams. The wiring of the panels sill be combined in the center. Also, more L-brackets. The bottom wooden 'beam' acts as support when placing the panels. In addition it...

@all, It seems quite some people start getting frustrated with the amount of info hidden and spread out across multiple threads. Threads on interesting topics seem to grow very long, information is repeated, some of it lost in the noise. Would it be possible to integrate a wiki in this site so...

I own a company or two where we build things like GPS trackers and radiation detection sensors, I do consulting work in electronics, software, security, and battery tech, and I teach at the local university where I also have a battery testing lab (currently being rebuilt).

My god people... don't make me move this thread to chit-chat...

Search has been upgraded. Give it a go.

We have users from China that contribute. Blocking IP ranges on an international site is counterproductive. Never mind that most of these bots spamming the site don't even originate from a certain country anyway. The last bots banned for example came from Montréal, California, and Germany among...

I'm probably one of the few on the opposite side. I blog about it, and I invite people over (that are local to me anyway) to have an idea what it takes and what's possible. Solar wasn't a thing here before I started; I'd like to think I helped at least a few look into it seriously.

For sake of trying to not pollute this thread, let's move JKESS discussions here: https://diysolarforum.com/threads/jkess-bms-all-the-things.93411/

YouTube is full of those fake scam accounts. I don't get how people fall for it... Basic security practices 101.

As I commented on that video: - Test should be done at 25C, not 11C or whatever it was. This accounts for at least 2% - Battery cells are 4 years old, count calendar aging for this especially since they're used in a warm environment. He didn't get 280Ah when he just got them either. -...

Please don't give users an idea by stating that you 'doubt' it will be an issue when in reality it is an issue - even in jest. You don't back-feed into the grid when the grid is down, ever. My dad knew people that died because of fuck-ups like this, and no I'm not going to spend time writing...

It doesn't need to hold a compression. It's cold welded together with the strands. I just cut an old bad one open:

I don't need them to support me. I want a BMS that does what I want it do do and stays out of my way. The old non-comms JK fits that bill just fine.