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

tails_naf

Wow, great post. Very tempted to pull the trigger on this

A few newbie questions - I currently have 4.8KWh Pylontech connected to a 5KWP Solis Hybrid inverter.

1) Would this setup work with that inverter, or must the inverter be replaced?

2) My inverter and batteries are in the attic and it can get pretty warm in there in the summer. Is there any danger of overheating / fire with this kind of setup, and if so, what mitigation do people use? The pylontech batteries are in a metal rack/cabinet, so could perhaps re-use that for these cells, but if there is a better/safer option would appreciate any advice.

3) Any links for what configuration to use - I see above the diagrams for 16s, 16s2p, I assume the goal is to get ~50V on a string, is that correct?

graememk

1) will work with your current inverter.

2) Batteries generate very little heat and are rated to work at 30+ lifepo4 are a lot safer (no thermal runaway) (gwl have a video that show them comparing li ion, lfp and titante cells)

The cabinet could be used if you can fit the cells in them.

3) yeah the aim is "48" volts but really it's 51ish under normal working conditions.

tails_naf

https://www.boards.ie/discussion/comment/119130950#Comment_119130950

Perfect, thanks.

It looks like the operating environment should be 0 to 40c. Not sure if the attic could exceed 40c on a hot day, I'd imagine it could. Is there any safety built into the BMS to not charge/discharge in case the temp is too high/low?

championc

Not sure about too high but absolutely is for too low. The Seplos has several temp sensors

irishchris

https://www.boards.ie/discussion/comment/119132607#Comment_119132607

Can these temp sensor cables be extended in the same way as the other BMS cables as mine are only long enough to cover first half of the packs?

tails_naf

Have prices ticked up? Seeing 1600/1700 odd euro for 16 200mah cells now on alie press.

irishchris

https://www.boards.ie/discussion/comment/119133131#Comment_119133131

I noticed pwod and few others all about 2000+ dollars at the minute now but oye store still showing 5 batches left at 1300 euro at checkout after they remove the 300 euro adjustment

https://a.aliexpress.com/_mta3L9Y

tails_naf

https://www.boards.ie/discussion/comment/119133355#Comment_119133355

Some of the comments on that link are interesting, many say they are used cells being sold as new, capacity is lower as a result, etc. Many comments suggest the same, so does not look great. How trustworthy is that seller?

irishchris

https://www.boards.ie/discussion/comment/119134870#Comment_119134870

Majority here used either this store (oye) or pwod. Essentially I think they are the same company though and ordered 16 cells from each on same day. All arrived at same time and communication from both companies were identically worded.

No issues so far with mine and didn't see anyone else with capacity issues apart from one recently here who definitely had under capacity cells, from memory think his were only coming in at 140ah from a 200ah rating

Mr Q

https://www.boards.ie/discussion/comment/119135513#Comment_119135513

But are people testing the capacity? I don't have any means to do it properly and I assume most don't

Based on other users here most seem very happy using Oye/pwod and have had no issues

mrohare

Right, so not charged up front then. Thanks.

Is any of the 2 stores mentioned by @championc better, more reliable, quicker etc than the other?

championc

No, even a feeling that they could both be one and the same store.

But we have all only bought from these two. I don't think I would trust others. I ordered from another for a very good price, which was too good to be true. Thankfully got my refund.

mrohare

Thanks @championc I ordered from oye this evening. My 26 county mate is getting a delivery soon.

Mr Q

https://www.boards.ie/discussion/comment/119138037#Comment_119138037

I think the same people are operating on more than just those two names on Aliexpress.

There are several users here, myself included, who ordered batteries with a price that was too good to be true. The Aliexpress refund is slow but at least it is there to cover this.

championc

https://www.boards.ie/discussion/comment/119148653#Comment_119148653

Those other fakes would not be linked to PWOD or OYE.

Be very careful. These crowds will claim that they are at the post office for collection and say that they are signed for. Email the relevant AnPost section to get confirmation that the tracking number is either fake or that no such item has hit these shores, or whatever.

Mr Q

https://www.boards.ie/discussion/comment/119149575#Comment_119149575

Just to be clear, it appears to me PWOD and OYE are also selling under additional names on Aliexpress.

Not that I had purchased from either of the above and didn't receive the batteries. I don't think anyone here has had that issue with them.

Effects

I think I might have missed it, but what's the max discharge output from your system?

Only just realised the limitations of some off the shelf systems while looking into them recently.

championc

https://www.boards.ie/discussion/comment/119150299#Comment_119150299

Discharge is controlled by the lowest common denominator between the Cells (highly unlikely), the BMS, or the Inverter

Effects

And what is that for a system like this? is the BMS the LCD? Pylontech are about 4kw, so curious as to what it is from this system.

I presume that for a 4kw battery discharge you also need a 4kw inverter in that case, even if you only have, for example, 3kw of panels?

Trying to work out where I can place my batteries, inverter and cabling that will work. I've got a 2.5mm2 from my inverter to fuseboard, but not sure if I'll need to upgrade that. Possibly not if I can't draw more than 4kw. As it is, to increase my panel count I have to add a second string, as I'm not sure I can get the same panels again. That would leave me having to run the extra cables to the inverter. Original installer was supposed to do that, but didn't. So I'd probably have to move inverter location.

reklamos

https://www.boards.ie/discussion/comment/119151036#Comment_119151036

You need to check al the componnetn in the chain. Having 4kW inverter does not mean it will charge/discharge at 4kW. The older 4G solis inverters are capped at ~3.4kW where as the 5G can do ~5kW. Tipically recommended battery charge/discharge rate is at 0.5C of its capacity. So 10kWh battery should be charged/discharged at 5kW. And then there is also BMS that has its own charge/discharge rates. A good rule of thumb is to overspec so none of the componnents are contantly working at their limits.

championc

Just to clarify, I think the CALB cells (which most on this thread have bought / will buy) are either rated for 2c or 3c.

I think it's the likes of Pylontechs that are 0.5c rated. They possibly only have small pouch cells inside.

reklamos

Even within CALB it does varies depending on the battery type. The 200Ah ones that most of us have bought are 0.5C(https://www.evlithium.com/CALB_Battery/42.html) other types go higher but DOD lifecycles for all of them are measured at 0.3C. Also max discharge rate is usualy 2x higher than charge rate.

G0ldp001

It would be great is someone put together as a kit for Ireland. I think lot of us are interested.

graememk

https://www.boards.ie/discussion/comment/119154378#Comment_119154378

Issue is by the time you get everything together for a kit, and providing support, a warranty? You'd be close to off the shelf batteries.

championc

https://www.boards.ie/discussion/comment/119154378#Comment_119154378

If you can use a screwdriver, a spanner and a digital multimeter, then this is ridiculously doable by all.

And I can assure you that all who have done it so far are from all walks of life. Probably most are average general DIYers

mrohare

quick question or 2..

1. What are peoples feelings on compression? - yes/no/how etc.
2. those of you who have built already - did you clean battery terminals/lugs etc. and how?

thanks.

dermotx

https://www.boards.ie/discussion/comment/119149575#Comment_119149575

Hi. I'm not sure I understand that comment. I intend buying from PWOD here https://www.aliexpress.com/store/5384082?spm=a2g0o.detail.1000061.1.6a841216Zqnnn0

Is the following the procedure?:

I buy the usual way on Aliexpress and pay for the batteries immediately. Before I pay, Aliexpress or PWOD will subtract the VAT.

They will give me a tracking number when the batteries arrive in Europe.

I don't understand the "be very careful" warning about contacting An Post.

Just as a precaution to make sure I am getting the batteries from PWOD and not some fake store, does anybody have a contact email for PWOD please?

Thanks

Dermot

championc

My "be careful" comment related to cheaper sellers and you trying to get refunds from these sellers when the batteries don't materialize.

The seller I tried to buy from kept insisting they they were at the post office for collection

BuzzFish

https://www.boards.ie/discussion/comment/119154378#Comment_119154378

I've been quiet since the original post as hit a very busy work period but the system is working away great. As others have said, a couple of simple tools, bit of planning and careful work and this is an easy assembly. There would be no value in someone building kits to sell on.

If anyone has specific questions, drop me a PM and I will reply in thread with your questions as I don;t get in here as much as I'd like and have missed multiple questions being asked.

dermotx

https://www.boards.ie/discussion/comment/119090548#Comment_119090548

Could I ask please where you picked up the Sofar me3000 inverter and how much it cost?