10kWh LifePO4 DIY Battery Addition..... Here is my write up.

spose · 15-07-2022 11:35am

I’ll try that later on. It’s running 4 hours now with only 2 trips. First another low voltage that reset itself. Second caused the bms to turn off. Have reached out to sofar as well with the error logs since a couple of the errors on it say to contact them if they are recurring.

spose · 16-07-2022 11:37am

Ran the realtime logging for hours yesterday and had a number of alarms reporting low voltage on cells 1 and 2 but the realtime logging never shows a cell drop below 3.2V. Sofar support came back looking to access the inverter but I didnt install a wifi stick so will have to see if they give me any other alternative.

I left the sofar off for the night and the battery turned on. Idea being if the alarms were due to loose cables or anything I might still get them even with nothing going on. No alarms overnight at least. Can I check something...I've changed the CAN protocol on the BMS to Sofar and using the cable that came with the Sofar to connect to the BMS. Is this correct and I shouldnt be using 485?

reklamos · 16-07-2022 1:14pm

https://www.boards.ie/discussion/comment/119345436#Comment_119345436

BMS must match the protocol on inverter. CAN and RS485 are completely diferent protocols. Seplos has BMS with CAN or RS485 but not both. The ones we use with Solis is CAN since this is waht Solis supports. The protocol is fine otherwise I would expect inverter to complain about missing battery.

Ignore this jsut seen the logs: As for cells, they do not need to drop below 3.2v, check the diference between the lowest one ant the highest one. Also do you get the alarms on when battery is being charged/discharged at high rates(50-60Amps)?

reklamos · 16-07-2022 1:30pm

Inspect your black terminal and white and yellow cables.

I would do the following tests:

Swap cells 1 and 2 with 15 and 16. If problem moves with cells, you have bad cells. If it stays do next test.
Swap the white/black terminals arround but you will also need to reconnect the balancing cables accordingly on the cell side. If after swapping the problem moves to cells 9 and 10 then the problem is with terminal block/wires. If it stays, it is Seplos.

If you do this, please do it safely and check everything multiple times.

championc · 16-07-2022 2:04pm

The Seplos CAN port should be connected to the Sofar CAN port with an appropriate cable.

I think the RS485 port on the Seplos would be to extract the cells and other data into Node-Red or something like that.

Similarly, the RS485 port of the Sofar is for reading Live data from a Sofar, or to remotely control a Sofar inverter (via a sofar2mqtt device)

spose · 16-07-2022 8:32pm

Thanks for the help. Will have to leave it now for a week. When I’m back I’ll try that suggestion and change cells 1&2. If it doesn’t point to the cells then I’ll probably strip it down and set it up simpler as a 16s1p and see if it behaves any different with half the cells. If behaving same then might bypass bms and under the default settings and see if sofar still alarms. At least that would definitively say whether the source of the alarms is the seplos or the sofar.

championc · 23-08-2022 8:07am

Maybe there should be in a 20kWh thread 🤣

Hopefully nice and snug for the winter, after repurposing the packaging

connesha · 23-08-2022 9:56am

https://www.boards.ie/discussion/comment/119509156#Comment_119509156

Nice.

I see you've left some space between the cells, looks like even a few mm between some ones that don't have insulation?

Is this in case they expand/bulge and put pressure on the terminals?

DC999 · 23-08-2022 10:38am

Wow, @championc great for a noob like me to see where we can go with this. More a comment in general - it takes a lot of space to have a lot of battery (ministry of the obvious of course). But I didn't think it would be that large. I've seen 5kwh like a puredrive, but not anything larger. You should post that on the solar setup thread :)

championc · 23-08-2022 11:37am

https://www.boards.ie/discussion/comment/119509617#Comment_119509617

The gaps were more the way the ended up after locking up the bolts on the busbars, and also the space I had in the foam coffin. So nothing deliberate going on here. In each 4, I have now put the temperature probe between cells 2 and 3

championc · 23-08-2022 11:42am

https://www.boards.ie/discussion/comment/119509812#Comment_119509812

Context is everything. Beside the chars on the left gives some impression of size. These cells are damn sturdy things and I bet several who got them didn't quite expect how big they actually are.

hwshaw · 24-08-2022 1:38pm

Has anyone bought cells lately and have had a good experience of the seller. That is the cells arrived and were as described with correct capacity?

I see OYE and PWOD store mentioned here as good. I was close to buying from OYE 16 x 200ah cells. The ribbed metal case style. Then noticed on the OYE store the smooth case version was more expensive. When you read the spec there is different operating specifications....does it matter?

Also looked at Alibaba some good prices. You see a seller with on the site good review....google the seller and some discussion boards inside and outside Ireland state they are good then others slating them.

Its a big investment so what to get it right or is it a case of roll the dice?

E30M3 · 24-08-2022 2:14pm

https://www.boards.ie/discussion/comment/119515482#Comment_119515482

In my experience if you find an issue after the 15 day Aliexpress window you are on your own. PWOD/OYE (Same seller) will not give two hoots.

You could try paying with Paypal but you are rolling the dice with any seller really.

hwshaw · 24-08-2022 2:29pm

https://www.boards.ie/discussion/comment/119515698#Comment_119515698

Yes this is my thoughts.....I do question though on OYE for example as they have different technical spec for cells with the same capacity?

To buy a capacity tester the cost on Alibaba is circa 185 euro for a 40A machine. What's the benefit\risk of diagnosing a bad cell?

Does anyone have a capacity tester to be borrowed\rented and paid for in notes....or beer?

I actually think OYE etc are little more than agent\re-sellers from an office they just buy in and sell out.

championc · 24-08-2022 7:57pm

I don't believe that a single buyer from PWOD or OYE have been left without their batteries. Getting the VAT off at the checkout and them arriving without any further charges is a huge bonus.

Yes, people have had issues with the capacity , but I think it's more than compensated in the price, and the knowledge gained. I got my second set about 3 weeks ago.

The CALB are 200Ah cells with a very strong plastic casing, and have large bolts and busbars. The flat cased cells all currently appear to be 280Ah cells, in Aluminium casings, and smaller terminals and busbars

S' · 24-08-2022 8:19pm

Finally getting around to top-balancing my cells. Just waiting on a capacity tester from AliExpress to make sure all is ok before I start into it🫣

munsterfan2 · 24-08-2022 8:55pm

https://www.boards.ie/discussion/comment/119515777#Comment_119515777

I have a capacity tester, bought it to test my cells to prove to OYe they were crap, not that they cared. Just over 6 months now and one of the cells is gone completely. It did run for about 3 months with an SOC of 125, but now if current goes up to 40a cell 12 just collapses, then jumps back when the BMS tries to recharge. Unless I get a refund from the bank, I have applied for a credit card charge back, this is eur1200 down the toilet.

Let me know if you want to borrow the tester.

garo · 24-08-2022 9:27pm

Only one cell looks bad tbh. If you don't get your money back you can always buy a single cell and replace cell12.

graememk · 24-08-2022 9:28pm

https://www.boards.ie/discussion/comment/119517789#Comment_119517789

Can the seplos be configured to run as a 15s?

garo · 24-08-2022 9:31pm

https://www.boards.ie/discussion/comment/119517794#Comment_119517794

I don't think so. Someone asked that in the https://diysolarforum.com The BMS needs to read 16 cell voltages.

munsterfan2 · 25-08-2022 11:51am

https://www.boards.ie/discussion/comment/119517789#Comment_119517789

Will probably have to do that, although it was by no means the worst when I tested capacity. Will look at restricting input / output current in the meantime

BTW, does anyone know where to set a charge / discharge limit, is it the BMS or the inverter ?

Thanks

garo · 28-08-2022 4:42pm

Depends on which BMS/Inverter you use. It could be either/or. The BMS typicaly sets voltage limits and the inverter SOC limits.

noelocon · 29-08-2022 4:20pm

"I also sourced some 25mm2 cable for the battery wiring. I had some lying around and bought a couple of lengths with lugs connected but as I discovered that I needed different sizes of lugs on each end of cabled I would advise to make your own cabled up.".....

I watched the WIll Prowse video on wiring and it got me worried in case I used the wrong rated cable. I've was looking at getting Bolatus 2Pcs Battery Inverter Cable 1m 3AWG/25mm² from Amazon but it's rated to only 100amps and I have 16*200amp batteries.

Is it better to get copper welding cable ?

great write up BTW

championc · 29-08-2022 5:30pm

The batteries' charge and discharge are restricted to the lowest common denominator, so I expect the limit of the inverter to to 100Ah, and likely lower

unkel · 30-08-2022 1:39am

@noelocon - you'll be fine. Your battery is 200Ah, but your inverter is unlikely to even charge / discharge your batteries at anywhere near 100A. Your 25mm2 cable is fine

Now the lesson you should take from this is to use the correct units. Your batteries are not "16*200amp". You have 16 cells in series and each has a capacity of 200Ah. So your total battery pack has a capacity of 200Ah also.

noelocon · 30-08-2022 8:15am

https://www.boards.ie/discussion/comment/119540355#Comment_119540355

yea good call, better safe than sorry ;-)

aleesi · 02-09-2022 2:03pm

Hi,

Apologies if this is been already answered (or if it doesn't make sense at all). I see many are opting for the Seplos BMS, can this BMS work either in parallel or as a master with any other brand like Puredrive, Pylontech or Dyness?

aleesi · 02-09-2022 2:06pm

https://www.boards.ie/discussion/comment/119560228#Comment_119560228

I will answer myself, found some info in their official website as per below. Has anyone tried to parallel a Seplos based battery with Puredrive or Dyness by any chance?

The default is the Pylontech CANBUS protocol

Goodwe

Growatt(The default is SPF(off-grid) protocol. If your inverter is SPH(on-grid) , please contact the sales person)

Victron

LUXPOWER

Sofar

Deye

Sermatec

Renac

TBB POWER

Solis

SMA

Foxess

IMEON

slave1 · 02-09-2022 3:21pm

What do you mean? Are you thinking of pairing say, a Dryness battery with a DIY setup?

championc · 02-09-2022 4:11pm

https://www.boards.ie/discussion/comment/119560228#Comment_119560228

A BMS is for building a pack from RAW cells.

Each of the bundled solutions like the Pylontech, Dyness, Puredrive are pretty much the same thing, but packaged in a fancy box.

With a DIY solution, you can actually see the physical cells and see the busbars joining them together.

If you saw the inside of a Pylontech, you probably wouldn't buy one

aleesi · 02-09-2022 5:03pm

https://www.boards.ie/discussion/comment/119560678#Comment_119560678

Exactly, for those who already has a battery (in my case I ordered a puredrive that hasn't been delivered yet), let's say a pylontech, per Seplos datasheet it appears that the BMS is compatible with pylotench canbus protocol which means (in theory) you could parallel a pylontech with a diy with Seplos BMS over canbus, they should be able to act as master / slave and talk to each other...

So it would be great to know if anyone has tried this setup as surely many people would have bought a PV system with battery in the past (pylontech / dyness / puredrive) and would be looking to expand capacity, the DIY approach would be a great option to add more battery storage to an existing PV + battery. In my case the battery is still on its way and I would consider cancelling the order (specially if both puredrive and DIY were not compatible at all) and go straight for the DIY solution. If I was to bite the bullet and stick to the puredrive (5KWh) I still would be interested in adding another 5-7 KWh to my system at a later stage, but rather from a DIY battery pack. So any feedback would be much appreciated as I think I could still cancel the puredrive if the seplos is not compatible, surely with the current demand and backlog the provider wouldnt have any problem at all to give my battery to the next in the queue...

Thanks in advance

slave1 · 02-09-2022 6:09pm

Oh, not sure about that, others more knowledgeable can kick in….

unkel · 02-09-2022 7:03pm

Technically it's possible, but it makes no financial sense to add a DIY battery to a premade one. Just sell the premade one. Even second hand it will pay for most of the cost of the DIY battery that's 4 times as big 😁

aleesi · 03-09-2022 10:34am

https://www.boards.ie/discussion/comment/119561692#Comment_119561692

Fair enough! since I haven't received mine yet I'll see can I cancel the order and go down the DIY route. If not I'll see I seplos tech support can shed light. Thanks for the feedback

poker--addict · 03-09-2022 1:07pm

https://www.boards.ie/discussion/comment/119560940#Comment_119560940

But would i be misinformed to say that the bundled solution wont leave someone having to consider concepts like balancing ? (which is probably easy if you understand it).

Reading posts from spose about the alarms he got too, and munsterfans dead cell, sort of supports my concern that a lot of time is involved in this?

championc · 04-09-2022 12:28pm

Well these bad boys got me through the night without needing to charge them from the grid, after the sh1te day yesterday 😀

slave1 · 04-09-2022 2:35pm

Have you two Seplos there? I just went with 2P16S (not sure of proper expression)

championc · 04-09-2022 2:52pm

https://www.boards.ie/discussion/comment/119569752#Comment_119569752

Yes, possibly overkill, but I had a spare Seplos, which I know I could have sold.

But I have full control now over each string. I have the marine knobs on the + and - cables, so I can have strings 1, 2 or 1 + 2 active

unkel · 04-09-2022 4:12pm

A BMS lead can only manage one cell. So strictly speaking if you have 32 cells, you should have them as two strings of 16SP1 each with their own BMS. Like @championc has.

graememk · 04-09-2022 5:42pm

https://www.boards.ie/discussion/comment/119570257#Comment_119570257

although a paralled 200ah cell electrically becomes 1 400ah cell. None of these bms's have much of balancing power anyway, 100ma at a push..

Im running a 16s2p. There would be no reason a 16s4p wouldnt work. Just dont rely on the bms to do much balancing, would be important to top balance first!

spose · 04-09-2022 7:30pm

https://www.boards.ie/discussion/comment/119569855#Comment_119569855

Where did you split the battery cables…1 from inverter to fuse/breaker and then 2 out, further down the line or using the bus bar on the first bms to feed the second?