DIY 24v 340Ah LiFePO4 Battery Boxes

[nowty]

The great thing about building your own is you know exactly how to fix it, if one of my Pylontech's went south, it would end up in a skip.

Would love to hear you do a review in a few months about how much better (or worse) the lithium is over your good old LA.

ooh you big fibber! it would end up being stripped, re engineered and probably end up with three times the output and the ability to conjure electrons out of thin air all on its own!

Moxi

If the cells in the Pylontech's were the standard block cells I would agree with you (at least the first bit ), but I have seen a tear down video of one and they are pouch cells, with nightmarish very complicated PCBs. But then, they never seem to fail.

Another thing I liked about AlBargey's build is the attention to detail on the equal length cables to the batteries. I have a 20cm difference between two equal battery banks and it makes a small but measurable difference. I keep meaning to lengthen one of them to match, another ToDo list item.

[Moxi]

Yes I too have seen a pylontech autopsy and as you say its a very different beast internally.

Als build and attention to detail is marvellous, I would love to be able to achieve even a fraction of that but when I do things I usually have three snotty inquisitive manlings around my knees picking up washers and bolts and losing them at a rate you would think to be IMPOSSIBLE!

Still I would rather the kids have an interest rather than taking the blanking option regards my eco hobby activities, give it another 8 years and I will have many hands to make light work, in a Frotter type stylie. I even have an old 12V mobility scooter that I can turn in to a utiliy boogie like he did

Moxi

[AlBargey]

Thanks folks. It is addictive watching the Victron VRM site and seeing what's going on

Annoyingly, we are shaded by a large block of flats and industrial buildings until around midday, if the sun comes out! But we do have over 10kWp installed, so I look forward to white high cloud mornings, as we get more generation than if it was blue sky until the sun comes over the buildings.

I woke up this morning and saw we had a 'phase' down on the main distro panel



But then remembered that's because the Quattro was still programmed for the old batteries to cut the power to the electric shower when SOC hits 50%, so will need to re-programme the assistants and reboot.

Currently it looks like the internal BMS's thinks we're at 43% SOC and the SmartShunt says 48.9% I believe the SmartShunt more, but it is only the first discharge cycle, so the BMS's may need to sync to the cells still.

[AlBargey]

I am surprised that they still sell the batteries with solid links between cells. When all the cells get compressed the solid links between the cells will cause the battery to fail with expansion / contraction over time. Why they don't sell them with flexible links. ????



Also selling the BMS system with no fuses on each cell cable is hard to understand.

I did ask for the flexible links, but the Gotion cells are fatter than standard, so they need to be longer, but no one seems to make them.
It's a shame, but there are very few reports of damaged terminals due to expanding cells, and if your cells are expanding / bulging then they're being over charged! The battery boxes clamp them all together fairly well, so I don't expect it to be a problem on low C charge and discharge cycles for off-grid use.

The BMS cuts the negative when programmed or in a fault, so the breaker is on the positive, but TBH, I'll be relying on the NH fused disconnects, not the DC breaker

[Tinbum]

I did ask for the flexible links, but the Gotion cells are fatter than standard, so they need to be longer, but no one seems to make them.

I'm presuming you've looked on aliexpress.

They are expensive though!

[AlBargey]

, well done!

I may have busbar bms centre point envy.

26kWh is close to where we are in a 5 bed home and gets the job done nicely. I assume your goal is a little different maybe? I would guess the barge uses less than.our house in a 24hr cycle so thought you might have a multiple day poor weather scenario in mind?

Thanks Joeboy

I was initially very happy with myself.. with the original home made bussbars, but it is a bit of a mess, and the time I spent making them and materials versus the quality and ease of use of the Victron expandable bussbars, I decided it was time to do it properly for the new bank.

The old Bussbars:



We use 8-10kWh day roughly, so we still need to run the genny to top up when it's dull in December January mostly. You can see usage over time on the VRM portal by setting the date ranges.

If feeling inquisitive, there's whole ton of peoples installs across the world to view if you ever want to see other installs and what they're up to :

https://vrm.victronenergy.com/world/

[AlBargey]

I did ask for the flexible links, but the Gotion cells are fatter than standard, so they need to be longer, but no one seems to make them.

I'm presuming you've looked on aliexpress.

They are expensive though!

Yeah, no joy for my length on aliexpress, but I didn't specifaclly ask any sellers there if they could make them to spec, or look for too long, mostly alibaba, ebay, amazon, which aren't as good for that kind of specific small thing.

[Stinsy]

The great thing about building your own is you know exactly how to fix it, if one of my Pylontech's went south, it would end up in a skip.

Would love to hear you do a review in a few months about how much better (or worse) the lithium is over your good old LA.

I think that is a bit dramatic! IF the BMS failed in a Pylontech, a man of your calibre would lobotomise it, connect the cells directly to the terminals and retrofit a balancing board, without breaking sweat!

[AlBargey]

The great thing about building your own is you know exactly how to fix it, if one of my Pylontech's went south, it would end up in a skip.

Would love to hear you do a review in a few months about how much better (or worse) the lithium is over your good old LA.

I'm hoping I don't have to fix it!

But yeah, at least I know with more detail what it should be doing, how or why it's doing it and what it is doing, compared to the Pylontech installs I've helped with.

I'll definitely try to keep the thread updated.

[Stinsy]

The great thing about building your own is you know exactly how to fix it, if one of my Pylontech's went south, it would end up in a skip.

Would love to hear you do a review in a few months about how much better (or worse) the lithium is over your good old LA.

I'm hoping I don't have to fix it!

But yeah, at least I know with more detail what it should be doing, how or why it's doing it and what it is doing, compared to the Pylontech installs I've helped with.

I'll definitely try to keep the thread updated.

The most interesting thing about LiFePO4 is how dull they are! They take charge, they give it back, day-after-day, year-after-year. There is no maintenance, there is no trouble, set-and-forget!