Hi from Portugal - 48v DIY battery help

[Joca]

Hello to all

I'm from Aveiro, a great region of Portugal

I have a Goodwe 6KW G2 and 14 solar panels with a total 7.2kw capacity.

I'm searching for a stable and consolidated project of diy battery pack. 48v

My mains concerns are:

- Where to by good cells in europe?
- Where to buy the chassis in europe?
- How long this systems are running?
- HAzards and explosions history
- Can i put the battery inside my house? (25º - 30º max temp)
- Are you compressing the battery pack or not? Does the chassis take care of this?


Thanks a lot for your help

 

[SeaGal]

Where to by good cells in europe?

nkon.nl has a good reputation amongst European customers on here.

 

[Joca]

And about compression and/or chassis for the batteries?

nkon is the only option?

thanks

 

[SeaGal]

And about compression and/or chassis for the batteries?

nkon is the only option?

thanks

Fogstar in the UK also supply raw cells, pre-made battery packs and "kits" based on the Seplos Mason box and BMS. But we're obviously not in the EU now

As for compression, there are more threads on here about compression than you can shake a stick at - search is your friend.

 

[Suijkerbuijk]

About compression.
Well yes and no.
If its a big deal than alle compleet battery pack in the store will have it.
And no its just tape and nothing more if you open it.
Really you only see it by diy self project

Explosion .
It have a blow off systeem so normal use it will not burn down your house or blow up a car
Its one of the save battery you can have.
Even lead Battery can explode.

My systeem are running 2 years now.
But its only a 12 volt systeem .
The battery i use cost a 1000 euro for 150Ah .
Yes i can go for cheaper but , i go for battery that are EU make (Franse) but cells are still china.

I living on a boat .
The spot i use in the boat its about 20/25 celcius.
Even if inside go up to 40 celcius the battery stay cool.

Wy i not go for a DIY systeem.
Wel its insurance for the boat .
Reason i go for a battery systeem that is ready from the store so i do not have future problem if somtings happens.
And can easy replace if i have to.
If its fail i can always switch back easy to a lead battery systeem.
If i'm in a other country and do not have a lifepo4 battery on the shop.
So the systeem always work.

 

[Daddy Tanuki]

Welcome to the forum.

My mains concerns are:

- Where to by good cells in europe?
- Where to buy the chassis in europe?

sea Segal and other EU members answers

- How long this systems are running?

System time: for me 8 years total, 3.5 years with AGM, 4.5 years with LiFePo4.

Day to day power use: (70 Kw -1300 aH, 48 volt system) up to 4 days with no solar input, this is powering refrigerator, freezer, split pack a/c, and sewage pump all 24-7 (summer), or refrigerator, freezer, sewage pump and heat tapes for water lines 24-7 (winter).

- HAzards and explosions history

No explosions, but I have been shocked once or twice (DC ) while working on the system due to my own stupidity.

- Can i put the battery inside my house? (25º - 30º max temp)

with the power that a pack can make I always suggest separate form living spaces, but this is simply my preference.

- Are you compressing the battery pack or not? Does the chassis take care of this?

I built my own compression rig that also serves as a battery heater for the winter, -20°c here is not unusual (temp range is -20°c ~ 30°c).

Thanks a lot for your help

for what my help is worth, you are welcome, and I wish you the best of luck in your endeavors.

 

[Joca]

Thank you.

I read about compressions and it's not a big deal i think. The diy chassis are doing it already but without knowing the force in Nm or Kgf. i'm searching for the chassis but in europe it seems that's not so easy to find. Alibaba? aliexpress? The Jk bms seems to be the choice to go and the option for active balancing is still a bug for me. There are some people that do the capacity tests and calibrate the pack for the high and lows of the worse cell. Is this right?

Thank you

 

[Daddy Tanuki]

Thank you.

I read about compressions and it's not a big deal i think. The diy chassis are doing it already but without knowing the force in Nm or Kgf. i'm searching for the chassis but in europe it seems that's not so easy to find. Alibaba? aliexpress? The Jk bms seems to be the choice to go and the option for active balancing is still a bug for me. There are some people that do the capacity tests and calibrate the pack for the high and lows of the worse cell. Is this right?

Thank you

if you have the time to do it I would highly suggest that you capacity test your cells.

On my first batch of cells, this was what was causing me issues with cell balance. (4p16s). after fighting with pack balance for about 6 months I capacity tested all of the cells (64) I was able to reconfigure the pack into a 3P16s and actually gained usable capacity.

8 or 9 of my cells were so far out of spec that they were dragging the pack down. by removing the lowest performing 16 cells and pairing the other cells into like internal resistance and capacity 3p groups i was then able to balance the pack better and gained usable capacity.

to compress or not to compress is something that everyone needs to decide on their own. if the battery box you choose does nto allow the cells to expand then you have achieved the same result. my cells are not in an enclosed box, but are under compression. the compression fixture also acts as the framework for my heating pads helping to spread the heat out more evenly so prevent hot or cold spots.

first set of cells (CALB) during test assembly without compression. I had 4 sets of these (64 cells) and one set had issues.




My newest (Winston) cells they have no balance issues at all.




this is a photo of my latest cells I purchased. they do not have any blaance issues but were quite a bit more expensive then my first batch of cells. the orange pads are heating pads wired in series across the bottom and side aluminum plates which also act as compression plates so two for the price of one. then when finished the cells are totally enclosed in the blue XPS foam to help control temps.

 

[Zezo]

I have a Goodwe 6KW G2 and 14 solar panels with a total 7.2kw capacity.

I'm searching for a stable and consolidated project of diy battery pack. 48v

I have an ES G2 Goodwe my self and I'd advise researching if you'll be able to get the inverter to work with your BMS for a DIY battery. I never intended to install a DIY battery but during my research I have seen mention here and there people having difficulty getting them set up and supported with Goodwe inverters.

Again I'm not saying you will have an issue, but I would recommend researching before buying.

 

[Daddy Tanuki]

I have an ES G2 Goodwe my self and I'd advise researching if you'll be able to get the inverter to work with your BMS for a DIY battery. I never intended to install a DIY battery but during my research I have seen mention here and there people having difficulty getting them set up and supported with Goodwe inverters.

Again I'm not saying you will have an issue, but I would recommend researching before buying.

to be honest, your BMS should be able to do its job without the coms. the same goes for your solar charge controller. while them talking can help in some ways, it should not be a necessity. if they cannot do their individual jobs on their own, do you really want them in your system??? my inverters, my SCC, and my BMS's cannot speak with each other. They are all separate items and both the inverter and SCC are tier one products, albeit dated a little hence the lack of BMS coms being built in. but guess what, the whole system plays nice and works like it should without the coms... would it be nice if they could? of course, is it a requirement? no.

 

[Zezo]

to be honest, your BMS should be able to do its job without the coms. the same goes for your solar charge controller. while them talking can help in some ways, it should not be a necessity. if they cannot do their individual jobs on their own, do you really want them in your system??? my inverters, my SCC, and my BMS's cannot speak with each other. They are all separate items and both the inverter and SCC are tier one products, albeit dated a little hence the lack of BMS coms being built in. but guess what, the whole system plays nice and works like it should without the coms... would it be nice if they could? of course, is it a requirement? no.

I agree with everything you said, I just didn't want OP to be blindsided by lack of communication or support.

 

[profesor79]

I am waiting for cells from Amy from Docan, so that was processed over Alibaba. There are some sellers that have stock in EU (Poland and Germany) - so you don't need to do a long wait for the cells. nkon.nl many times sells stuff that are on the ship - so be diligent reading their item descriptions.

I did my case by my own, and due to different reasons I keep the battery in my home-office room.
Compression is made by 10mm rods that are connected to 20mm plywood on top and bottom - but mostly to keep them in place.

Monitoring is crucial, as my first purchase on alibaba for balanced and matched cells was a f...up, but i am ok for the price to kWh ratio.
As you can see below my cells have some Ah capacity mismatch that leads to reduced capacity of the set, as the voltage is dropping rapidly on some of the cells.
With purchase from Amy, I also decided to buy cell capacity meter, so I will be able to match the cells on my own.

 

[Daddy Tanuki]

I am waiting for cells from Amy from Docan, so that was processed over Alibaba. There are some sellers that have stock in EU (Poland and Germany) - so you don't need to do a long wait for the cells. nkon.nl many times sells stuff that are on the ship - so be diligent reading their item descriptions.

I did my case by my own, and due to different reasons I keep the battery in my home-office room.
Compression is made by 10mm rods that are connected to 20mm plywood on top and bottom - but mostly to keep them in place.

Monitoring is crucial, as my first purchase on alibaba for balanced and matched cells was a f...up, but i am ok for the price to kWh ratio.
As you can see below my cells have some Ah capacity mismatch that leads to reduced capacity of the set, as the voltage is dropping rapidly on some of the cells.
With purchase from Amy, I also decided to buy cell capacity meter, so I will be able to match the cells on my own.

View attachment 229924

i think most of us get taken at least once in this game.

 

[profesor79]

i think most of us get taken at least once in this game.

we say if you not fail - then you will not learn, it is a hard way, but always progress :D.

 

[Joca]

Thank you for the guidance.

When you purchase 4 cell pack from docan (alibaba) or nkon , are they matched? The seller will pay atention to a 16 pack battery and provide them within the capacity range we want? Or is everything randomly sent to us? If that’s the case, what’s the worst case scenario I’ll be facing?

Thank you

 

[Daddy Tanuki]

Thank you for the guidance.

When you purchase 4 cell pack from docan (alibaba) or nkon , are they matched? The seller will pay atention to a 16 pack battery and provide them within the capacity range we want? Or is everything randomly sent to us? If that’s the case, what’s the worst case scenario I’ll be facing?

Thank you

this is just my thoughts and I have no proof other than my own experience.

This is a long read so standby: if you buy from a reseller, or "agent" you have no guarantees other then what they say to you. normally its 98% lies and bullshit.
If you buy form the Company that actually makes the cells then you can believe what they say. the difference in price is immense like almost 4-5 times what the resellers are selling them for.
Over the last two years, all of the sellers including every single one that sells to the members of this forum at one time or another were pawning off second hand and blemish's as if they were brand new EV grade from the factory... first it was no bar code or QR codes, then it was faked stickers, then it was faked QR codes applied to stickers, then it was re-lasered QR codes.

Finally Eve stopped it all by themselves lasering a "B" onto the rejects. once EVE stated doing that actual non reject cells started appearing as they could no longer lie and get away with it. but i personally doubt they are the cream of the crop. I would bet they are outliers that meet the EV standard but probably do not meet the match and batch standards. Once again this is jut my gut feeling.

I have bought both from vendors, and directly from the factory from a company employee who was communicating to me from a company email address. I also independently verified this by making several discreet email communications behind that person's back to verify with that company to ensure that they were not a scammer.

what was the difference? a five year warranty, packed and shipped in accordance with all applicable laws both Chinese and Japanese and international, batteries that were packed in an actual wooden crate not some combination of cardboard. The final difference was a price that reflected theses differences... some members here on the forum think that I must have been ripped off. No i was ripped off when I paid for supposedly grade "A" EV cells that turned out to be pull offs from a bus or an electrical forklift and resold by unscrupulous vendors. Yes they were cheaper but I got what I paid for... cells that need re-balancing about once a year, that did not meet capacity but have settled down at about 90% of nameplate rating after a year of use.

now the ones I bought direct from the factory, tested in at 120% of their rating, IE the 400 amp hour cells from Winston came in at 455-460 amp hours of capacity that was drawing at .5c and charging at the same (this was for testing, not actual daily use) they have not needed a re-balancing after 6 months and show no evidence of drift form the initial top balance. I am not using active balancers, and the puny balancers in the Dalys BMS's i use would not do anything anyway with a cell this big. they are right now just at the start of the 9th month of use. Other than while testing, the cycle use has been 70~100% daily verified by a bogart engineering trimetric shunt based monitor.

I have two of these packs in 16s (22kWh each, 44kWh total) along with a 3p16s pack (27kWh) of CALB cells i originally bought that together power my house 24-7 with no grid tie.

so if you are building this to power a solar shed, or power a couple of split pack a/c untis or as an emergency backup ,then go with the eve or catl or calb's that the vendors are selling cheap, they will suffice for what you want. if you are building for a house that you want to work daily for the next 20 years buy from the factory and pay the premium. once again this is all my opinion and your mileage may vary

 

[profesor79]

Thank you for the guidance.

When you purchase 4 cell pack from docan (alibaba) or nkon , are they matched? The seller will pay atention to a 16 pack battery and provide them within the capacity range we want? Or is everything randomly sent to us? If that’s the case, what’s the worst case scenario I’ll be facing?

Thank you

As @Daddy Tanuki said - it all depends for what you need the cells:
Recently I got 32 cells that were "ESS Grade", which meats no "A", but shall be good for storage, from Amy at Dockan, and as you can see, 2 cells were below 260 (one is re-test as I was not expecting that). Other tested at 280+-3Ah.

 

[Daddy Tanuki]

yes if you have the ability to capacity test and test for the internal resistance then you can do a basic cell match which will be close . almost not worth it for a single pack of four that you are playing with though.

if the OP wants it to learn with then the cheaper, the better (to an extent) as he can see all of the various problems that crop up, but i would not want to see him get robbed and then think that all cells are the same.

these days instead of saying things like grade "B" or whatnot they have renamed them into ESS at least they are getting more honest in how they label stuff and that is primarily due to places like this forum. a definite benefit for the novitiate.

 

[Daddy Tanuki]

Also depending upon how many cells you buy you can pair strong and weak together to get them to balance out better as well so Professor79 has 32 cells, if he is running say a 48 volt system then he could run a 2p16s setup where he pairs the storngest to the weakest and then next strongest to next weakest etc. etc. to make a pack that essentail works well and balances out OK.

thats what I did with the calb cells I had, I had bought a total of 68 over three orders and currenlty am only using 48 of them where I capacity tested all 68 and then also did a Internal resistance test on allfo them and then matched the best matching 48 up. that left me with 4 that were stellar and I kept as a sepeparte pack for a 12 volt system and then 16 that were varying grades of yuck. (actually only about 5 or 6 were total trash, but at 120 per when purchased that represents 700 USD totaly wasted.

 

[Daddy Tanuki]

here is aperfect example of used cells being passed off as new... the owner does not realise this of ocurse, he was jsut screwed like so many others were back then.

S

Thread '24v catl battery issue'

Jul 15, 2024

Hello All,
I must be using the wrong search criteria as I cant believe someone else hasn't posted something similar but I cant seem to find it. I have an 8 cell catl 280AH battery, an overkill BMS off grid running a well pump, all works pretty good. But I keep running into the same issue over and over and I finally have a little time so I am going to try to find an answer.
Short version: one of the cells charges faster and discharges faster than the other cells. This causes the other seven cells to never be charged up to capacity or discharged to capacity.
The long version: I...

• ShoNuff
• Replies: 11
• Forum: DIY LiFePO4 Battery Banks

• 

 

[Joca]

It's not so often i can find really helpfull information like i'm finding from your insights. Thank you

My goal is to build a battery pack that can support my house that has all the normal appliances and 3 or 4 a/c. In the near future i also want to support some of the daily mileage (10-15 km) of an eletric vehicle. I dont want an off-grid system but one that can pay for itself. So, i want to avoid battery problems because i dont the time to play and learn.

My system:

16x 545w bifacial panels
6kw goodwee inverter

My idle consumption: 150-250w

My average grid consumption without system: 300kw/month - without a/c. I will be getting those till the end of the year. Maybe my winter average consumption will get close to 500kw/month.

The eletric vehicle is not the problem right now.

What are tour thoughts?

 

[Recovering EE]

It's not so often i can find really helpfull information like i'm finding from your insights. Thank you

My goal is to build a battery pack that can support my house that has all the normal appliances and 3 or 4 a/c. In the near future i also want to support some of the daily mileage (10-15 km) of an eletric vehicle. I dont want an off-grid system but one that can pay for itself. So, i want to avoid battery problems because i dont the time to play and learn.

My system:

16x 545w bifacial panels
6kw goodwee inverter

My idle consumption: 150-250w

My average grid consumption without system: 300kw/month - without a/c. I will be getting those till the end of the year. Maybe my winter average consumption will get close to 500kw/month.

The eletric vehicle is not the problem right now.

What are tour thoughts?

On the EV charging side of things, you'll want to be able to charge at different power settings, to better match your system's output capacity throughout a day. You can probably charge at 2-3kW during high solar times, but only 1kW or so over night. If you're only driving 10-15 km per day, a 1kW charge rate will probably be plenty. If I'm not mistaken, your mains is 230V at 50Hz, so the lowest you can go with the J1772 charging standard is 6A, which would be about 1.4kW.

 

[Joca]

On the EV charging side of things, you'll want to be able to charge at different power settings, to better match your system's output capacity throughout a day. You can probably charge at 2-3kW during high solar times, but only 1kW or so over night. If you're only driving 10-15 km per day, a 1kW charge rate will probably be plenty. If I'm not mistaken, your mains is 230V at 50Hz, so the lowest you can go with the J1772 charging standard is 6A, which would be about 1.4kW.

The 1kw is a battery limitation or are you figuring it from my home details i gave above? A little bit lost here. However i understand the charge/discharge battery ratings.
Thks

 

[Suijkerbuijk]

The 1kw is a battery limitation or are you figuring it from my home details i gave above? A little bit lost here. However i understand the charge/discharge battery ratings.
Thks

https://www.amazon.nl/VEVOR-elektrische-auto-oplader-EV-laadkabel-EV-laadstation/dp/B0CB5HHSTK?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A17D2BRD4YMT0X

Here you have a nice charger cable do not cost a lot and you have a lot of functions to the app.
Even timer and max charge profile.

 

[Joca]

Also depending upon how many cells you buy you can pair strong and weak together to get them to balance out better as well so Professor79 has 32 cells, if he is running say a 48 volt system then he could run a 2p16s setup where he pairs the storngest to the weakest and then next strongest to next weakest etc. etc. to make a pack that essentail works well and balances out OK.

thats what I did with the calb cells I had, I had bought a total of 68 over three orders and currenlty am only using 48 of them where I capacity tested all 68 and then also did a Internal resistance test on allfo them and then matched the best matching 48 up. that left me with 4 that were stellar and I kept as a sepeparte pack for a 12 volt system and then 16 that were varying grades of yuck. (actually only about 5 or 6 were total trash, but at 120 per when purchased that represents 700 USD totaly wasted.

I want to buy 16 cells for a good battery pack and no worries for next 10 years.

From your insights my options are:

Option 1

Buy Eve cells - Grade A verified - what sellers do you recommend in europe or aliexpress? Because at aliexpress i can find dozens and i feel unsecure.
I've looked at nkon. But it's the only place in europe i can find. Is it legit? Trustable?

Everyone is talking about a person called Amy...And others...it's really frustrating that i can't know for sure from where i must buy the cells. Then, you have a lot of different cells when you look at the pictures. Threaded bolts and others...

I don't want to play with the batteries till o find good ones and match them. However i'm considering buying the capacity tester and the internal resistance device for the purpose of continuous maintenance. But i dont want to find after 2 years that i have to buy more 4 cells because the pack is not so good anymore. Because after a 20 year period the overall price would reveal that at the begining of this endeavour i should have bought a 15kw pack from a renowed brand like pylontech, LG, Byd and others.


Option 2

Buy other brand - premium - what are the name of the brands and where can i find them? Still within a diy project.

Conclusion:

Going the diy route, a ~15kw pack would cost ~ 1800€ (case included)
If i have to buy another 4 cell pack every couple of years (is this the worst case scenario?), and use it to balance the capacity of the initial 16s pack in the case of finding a bad cell, at the end of the 10 year project i had spent ~4000€

Can't do the math for the premium cells you talked about, like winston. Where can i find them?

If i buy a 15kw battery from a brand (10 year warranty) i'm spending from 4000€ - 5000€.


What are your thoughts?

Thank you.