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

bullit_dodger

As I said, everyone to their own and if it gives you peace of mind, that's important too and I'm not having a go at you or Dublin fire brigade for that matter. In the interest of a balanced thread, here is the Dublin fire brigade warning.

Dublin Fire Brigade shares fire warning about household appliances as they highlight common mistake - Irish Mirror Online

However, I was mentioning above specifically "dish washers", and to your point about "where is your statistically more chance"...here you go.

Faulty appliances cause 43 fires a week in England, research finds (electricalcontractingnews.com)

Fridge/freezers comes in at #8 and dish washers #7 in terms of occurrences of fire, at least in 2019. However, it shouldn't be forgotten that this is a country with 60 million people. <500 fires is a small number when you are talking about potentially millions of units, and many of those units were probably poorly maintained etc. That's not to say that it's "ok", every fire could potentially be the loss of life, only that it's a small number.

but we're going a little off topic in relation to the 10Kwhr Battery addon - but yeah, always interesting to me that people won't use devices when others in the house are left on ok.

https://www.boards.ie/discussion/comment/119603909#Comment_119603909

Thanks. I can see where your numbers come from, and it's interesting to see how figures produced by different sources can have different results.

In fairness, I wouldn't have seen it as having a go without the LOL. It's a serious matter when it goes wrong, and it remains the case that the Dublin Fire Brigade recommend unplugging all unnecessary electrical appliances at night - which means any advice here to run appliances at night is in contradiction of their advice.

And as regards the DFB advice, because of the food contamination risk people can't regard their fridge/freezer as an unnecessary electrical appliance.

But, as we agree, let's not get off-topic. I'm intrigued by the thread because I'm thinking about installing solar but a battery add-on looks very expensive and it's not clear what I'd get for the money.

imogen

I have two questions, the first is probably for @championc .

Roughly what physical space do your 2 x 5 kwh of batteries take up once assembled and insulated?

We are trying to figure where to put them in the house/outhouses.

The second is a bigger issue but related to the efficiency AC/DC points above.

After much thought, as we have a field with a good southerly aspect, we are thinking of a ground mount, even though they are more expensive. But the best position is nearly 120m from the house. I know that most inverters these days come with standard weatherproofing and can be installed outside. And that it's more efficient to transport AC versus DC over longer distances. But then what do you do with the batteries which need to be near or in the house?

Or is the practical answer no, if you want to have a hybrid inverter and batteries, you can't put the panels down the field?

Can you put the batteries in a cabinet under the solar panels down the field? We are coastal, I'd be worried about corrosion as we get sea gales and everything rusts here.

I know the term micro inverter tends to be confused with optimisers like Tigos, but maybe they have a role for this scenario?

Thanks! And yes, I know, we probably would have to get planning permission to put them in a field...

graememk

https://www.boards.ie/discussion/comment/119618982#Comment_119618982

With the right cabling, you can do anything really.

My panels are about 60m (on 6mm2 swa) away from the inverter, and that is 100m away from the main consumer unit (but I do have 16,mm2 cable going to the barn)

With the power levels we are dealing with, it doesn't really matter if it's ac or DC (regarding solar pv, because thats high voltage dc, not low voltage batteries)

Batteries need to be beside the inverter that they are connected to. Be it a storage inverter or a hybrid.

Also you'd want to be keeping the batteries warmish - they don't like freezing temperatures.

mrohare

I have received 8 of my cells so far (others stuck in post) from OYE. I topped them up to 3.67v with bench power supply. It dropped to 0.05a for few hours so believe they are near enough 100%, but when I capacity test them, the result is 135ah. Am I doing something wrong or could I have a bad capacity tester (DL24P)? Or should I be opening a dispute?

munsterfan2

https://www.boards.ie/discussion/comment/119629916#Comment_119629916

I'd open a dispute on aliexpress before your time runs out, my cells were similar and are now offline totally so unless I get a chargeback from credit card it's sunk money. If you need a second capacity tester I can give you a loan of mine.

mrohare

Thanks @munsterfan2, I am in Co. Down so guessing you are not close. I thought I might be doing something wrong. Low voltage cut off is 2.6, though cells are 3v at end of test, but 2.6 under load. I was testing at 20 amps. Maybe should be at 10 amps?

Dispute is looking like way to go thought.

munsterfan2

I'm not too far away, near Slane, up in Portadown on Friday to get leaf bms firmware updated. 20 amps is only .1C so should be no issue for cells. Did you save / graph the readouts from the discharge test. Try https://github.com/misdoro/Electronic_load_px100 if needed

mrohare

I think issue might have been with the cables I was using. The voltages on the tester were not matching my multimeter. I have crimped up 2 sets of very short wires. Used speaker wire for voltage pins and 2.5mm for amp pins. Voltage on tester is reading much closer now to both multimeters, though test only running for 30mins. I will be keeping a close eye. I had crimped 2 sets of 2.5 together before and cables were 50cm long. Will let you know how this test goes.

mrohare

So it appears OYE store is trying to rip me off. I put ammeter in circuit and used 2 different multimeters for voltage. My capacity tester is measuring accurately. OYE have sent me 150ah cells and not the 200ah I paid for. I have now seen a few 1 star reviews on aliexpress claiming the same thing, dated August and September.

championc

https://www.boards.ie/discussion/comment/119643845#Comment_119643845

If you lodge a claim, lodge photos but add arrows and large text simple commentary, that an idiot can understand, because you have to make a clear undisputable case. You only get one shot, so you need to make it count.

I personally lost another claim because I didn't spell out what my photos were saying. I had blurb in my claim, but pictures speak 1000 words !!!

munsterfan2

https://www.boards.ie/discussion/comment/119643845#Comment_119643845

It could also be that they are old / used 200ah cells and will deteriorate quickly as has happened to mine. After 2 months trying to run them as 140ah one of the cells died completely.

unkel

I've had a few claims before where I had to use video as evidence. I'm brutal at that sort of thing, but I was given plenty of chances to explain my videos and re-do some. I have got a full refund every single time I entered a dispute with AliExpress, in fairness to them. I'd say I've had at least 12-15 disputes over the last few years. I buy a lot of stuff over there.

Nelbert

Is this issue confined to the OYE seller or has anyone used PWOD and been impacted?

Considering a DIY battery to avoid day rate over winter but this is worrying.

mrohare

They refused at first but now offered a refund, BUT I have to pay postage!! It is ridiculous as cost of return is huge. Cannot get talking/messages to a real human on aliexpress and the eve bot keeps saying it is buyer's responsibility to pay return on this sale. Scam.

munsterfan2

Did you use paypal, if you did try to cancel your payment with them. You cant ship batteries back easily due to shipment requirements.

munsterfan2

Make sure to leave a review on their store before the time limit on that expires

unkel

https://www.boards.ie/discussion/comment/119651743#Comment_119651743

I've been there with batteries. Simply tell AliExpress that it is illegal to ship any battery with lithium in it to outside of the country. Simples. They accept that (and it's not far from the truth)

mrohare

https://www.boards.ie/discussion/comment/119651858#Comment_119651858

Good call @munsterfan2. Lodged a complaint with PayPal this evening.

mrohare

Hi @unkel, how do I tell Aliexpress? I just get their chat bot. Cannot find a link to a human chat or email etc.

unkel

Keep telling the chat bot that you want to speak to a human. Or better, do it formally through the dispute progress, you can update it with your statements

unkel

https://www.boards.ie/discussion/comment/119652196#Comment_119652196

I would wait until a resolution with AliExpress is definitely not possible. If needs be, threaten AliExpress that you will start a claim procedure with the credit card company if they seem to refuse

mrohare

https://www.boards.ie/discussion/comment/119652219#Comment_119652219

But, I can't even get talking to Aliexpress. The seller agreed a refund but I have to pay return. There is no option to do anything (on the page) but enter return details. I have searched Aliexpress site for a live chat or email address but it is only an automated "Eve" bot that gives generic answers. If you have any way to get a message to Aliexpress, please let me know.

munsterfan2

Any progress with your claim @mrohare

S'

For those that went the DIY route and purchased from OYE or PWOD, are you happy with the capacity?

Looks like I got used cells from PWOD.

Top balanced to 3.65v

Resting voltage is 3.4v, all within 20mV of each other and battery voltage is 54v

When a 10A load is on them they all drop to around 3.25v and battery voltage is at 52v.

If I turn on the oven the BMS (seplos) low voltage alarm cuts in, this is when battery should be >90%.

unkel

When your pack is resting at 3.4V (fully charged) and you switch on the 3kW oven, you get a low voltage alarm from Seplos straight away? Something strange going on there. What is that reported voltage and do your inverter and the Seplos both reported the same voltage? What is the alarm level on the Seplos set for? Some of the default values in Seplos are way over protective imho.

With any battery, you will always get voltage sag if you apply a load to it that is a significant part of its total capacity. So a 60A load on a 200Ah pack will not go unnoticed 😁

E30M3

https://www.boards.ie/discussion/comment/119704611#Comment_119704611

It sounds s if you have a BMS calabration issue currently. What BMS do you have and have you calibrated the battery capacity for the BMS?

S'

https://www.boards.ie/discussion/comment/119704922#Comment_119704922

Get a low voltage alarm after 20secs when I switch on the Oven. Pulls 80A on startup.

Yes, at the minute battery voltage is 55.3v on Solis inverter, Seplos BMS and on my fluke multumeter.

Inverter displaying 100% but the last few evenings when the battery is drained to 65% and then hits low voltage alarm when a load of around 11A is present during that time.

I loaded the following parameters to the Seplos and this firmware

Seplos BMS Modified Firmware.zip

Parameter 20220402_1210.xls

S'

https://www.boards.ie/discussion/comment/119705032#Comment_119705032

Seplos 48v 16s 200A BMS

https://www.aliexpress.com/item/1005003443741614.html?spm=a2g0o.order_list.0.0.21ef1802ZdxOvd

Seplos is unable to calibrate as it either hits low voltage alarm (discharging) or high voltage alarm (charging)

I have set the Seplos battery to 200A.

E30M3

https://www.boards.ie/discussion/comment/119705261#Comment_119705261

Did you do a controlled Calibration as per the instructions initially? Both of those things will happen but in a controlled way.

S'

https://www.boards.ie/discussion/comment/119705332#Comment_119705332

No, I didn't. Can you point me to these instructions?

championc

Personally, I charged my cells to 3.65v, one by one. When I finally finished with cell 16, I went back to the beginning again, since all were below 3.5v.

I previously read that LiFePO4 does NOT lose voltage.

So re-commencing charging, I once again charged each up to 3.65v. This time, each settled around 3.60 - 3.62v. Some cells took quite a while on this second round, so I am quite sure that there is definitely extra capacity which I would have lost had I finished after the first round

E30M3

https://www.boards.ie/discussion/comment/119705410#Comment_119705410

They should have been written on a leaflet stuck to the inside of the box the BMS was delivered in. Did you see this note on the box?

Calibration instructions also discussed on the SEPLOS BMS thread

poker--addict

Before I look at some videos of top balancing on YouTube, can anyone bring me up to speed in simple terms why batteries only giving say 60% of capacity until this step is completed? And why we use a bench power supply - like why doesn’t the inverter or BMS eventually sort it out? ( yes I’m starting looking at thus from a low bar 😂, at least until I see a cheap relatively trustworthy powerwall)

graememk

https://www.boards.ie/discussion/comment/119742458#Comment_119742458

To give an example, of how I think of it.

Battery pack is made up of usually 16 cells.

If them cells are thought of as buckets, that hold water for instance. Each bucket is slightly different size.

They are all holding different amount of water too. One could be at 50%, another at 75% and another at 25 %to give a extreme example.

When they are put in a string, they all fill and empty at the same rate. When any of the buckets get full, the bms stops all charging. So not to "overflow(overcharge)" that bucket

When empting the bms will stop discharge so not to " over empty (over discharge)" a bucket

Top balancing gets all buckets completely full so they all hit "full" at the same time. So that was they are all at the same state of charge. And all move as one.

The bms can balance cells, but it's like a slow drip out of the highest cells. It will get there eventually but it takes a long time.

It's good enough to keep it in check though.

There is active balancers that can balance at 4 amps (the neey for example) and they can move power instead of just burning it off.

poker--addict

Plain as mud thank you.

poker--addict

10kw or 20kw of batteries?

8kw of panels on the roof. Day night esb meter for now. Intend to get an EV once the car to house/grid tech is more widespread and doesn’t cost a fortune to hook to house- and that will be the cheapest large house battery anyone could want. So do I stick with 10kw, or is there any logic in 20kw? I am cash flow poor post panels so happy with avoiding 20kw cost unless there is strong roi reasons to pay up. Houses uses a lot of power, heat pump draining battery quickly probably isn’t ideal so I am thinking 10kw to manage shoulder peak hours is the way to go, pump uses grid at night, charge battery before sun rise. 20 might actually be counter productive as I write about it - as it will just get trashed by heat pump?

unkel

It's insane that decent €200 BMS have only passive balancing (which is plainly sh1t - not fit for purpose and lossy / inefficient as it just burns electricity from cells that are too high) doesn't have the built in active 4A balancing that a €40 balancer has. The active balancer takes electricity from cells that are too high, stores it in a capacitor and then sends electricity from the capacitor to the cells that are too low

I installed a balancer myself a couple of days ago (had it for years, never tried 🤣), the results are astonishing. And I don't even have to qualify that with "for such a cheap device"

Here's your man from the off grid garage about them: (summary: "you should get one")

https://www.youtube.com/watch?v=1SRUhgBdy_g

DC999

https://www.boards.ie/discussion/comment/119743013#Comment_119743013

What about no battery for now. And get an EV. You’ll save a grand a year on petrol (give or take) for ~15000kms a year. And tax is 200 quid. Charge on the cheap night rate so it’s the cheapest cost to ‘fuel’ it. And get the 600quid grant for the EV charger. Get the cheapest charger you can, not a Zappi that can take power from solar (as you get paid more in FIT that cost of cheap rate juice).

I got a 2nd hand Leaf a few months ago and it's brill. It's our only car now. So don't need to spend a fortune on EVs. Can if you have the deep pockets - we didn't :)

poker--addict

DC999 all valid points. I am waiting however because with two small kids and their belongings we “need” an SUV size EV. Straight away that means fairly large outlay, and not all of them make vehicle to grid/house power transfer easy. The two way power I think adds significant value to EV ownership ( currently, unless doing big miles, I think a lot are over priced). I think the lack of 2 way power from car to house will change rapidly now that big names like VW are getting there, and we should I feel get to a point where the house charger is not 1000s to support that two way power too. Happy to be corrected if wrong, sorry off topic.

poker--addict

is it easy to add more batteries later? i.e If I was to DIY 5kw, could I add another 5 or 10 later? Would there be issues if the first batch were 1 year old when new ones added?

Logic is better putting money to an EV with a vehicle to house a battery in it, but a 5kw battery would manage the issue of short-term clover on an otherwise ok say. Today is a prime example of some cloud and showers around but strong sun 70% of the time. The immersion is on and off manually 😂

Do people find 5kw battery gets them through "peak period" - suspect we will all eventually end up on smart meters. Will monitor my specific usage in that period over next week.

EDIT to add did I read 8 DIY batteries wont get me to required voltage so need to go 16 (10kw)?

unkel

No you couldn't really add another 5 or 10 later. The batteries would be mismatched. Well I suppose you could, but you would not get the full capacity. It's better to either make your mind up, up front. Or to sell what you have and buy more if you want to expand. That's what I did earlier this year. I had 10kWh, but bought 20kWh and then sold my original 10kWh

Battery prices are going up though and people are prepared to pay a premium not having to wait 2-3 months for the batteries to arrive from China. So I sold my old 10kWh for significantly more than I paid for them about 18 months earlier

championc

For the 10kWh vs 20kWh dilemma, I had 10 and had to start thinking about automating the process of charging based on the forecast.

But in the back of my mind, there was

A) I could buy 10kWh VAT free in case they cop on and stop it

B) I'd be covered with plenty for when Time of Use tariffs come and Day / Night meters cease.

C) I'd have no forecast worries

So I now have 20kWh. All I have to do is ensure that I have about 60% SOC each morning. If the day is crap, I have enought to get me to midnight, and if it's a cracker, I have space for that charge (from my 3.9kWp)

Throw into the mix the fact that you have 8kWp, I personally think you would be nuts only getting 10kWp.

Remember, you have your GivEnergy (or whatever it is), which will make back a huge chunk of the money you previously invested

poker--addict

Asked about 5kw get talked into looking at 20kw 😂

givenergy??

unkel

Givenergy? Eh no. And please read the last few comments again. A message from us battery loves to you:

Do not pay anyone to install any battery for you. You will lose a lot of money if you do. If you really do want a battery, install it yourself and make it yourself. And even if you do, it is unlikely to ever pay for itself...

poker--addict

Miscommunication . I don’t have a GivEnergy. I meant what was the previous posters reference?

championc

https://www.boards.ie/discussion/comment/119750528#Comment_119750528

Ah ok, so you have nothing currently ?

In any case, you have an 8kWp system. That can easily support a 20kWh battery.

A 5 will cost more than a DIY 10, and a 5 could be full in under an hour.

This thread is only about DIY building of a 10kWh bank, and all the info needed is pretty much in post #1 of this thread

poker--addict

I pulled trigger and ordered 10kw for a DIY job.

I agree 20KW at DIY prices would work far better for me, just post paying for panels too there is cash flying out all directions at moment so there is limits and 20kw will have to come later.

Anyone else at similar stage let me know.

unkel

Nice one, keep us updated when you get them and about your build. Now as a point of order, power is expressed in kW, the capacity of your battery in kWh 😃

You buy from PWOD, did they still deduct the VAT, how much did you pay for the 16 cells delivered?

poker--addict

PWOD, €1585 paid (so far). Reckon two full months for delivery.