not all can understand how much work, time and passion for to do these tests, thank you very much!

@SolarEngineering

Жыл бұрын

thanks!

@pavelsedov9982

4 ай бұрын

Да , но английский с русским акцентом ужасен!!😢😢

Thanks so much for the video. Sorry You had the problem with the seller and Alli express. I have been through so many disputes with Ally express sellers but I’ve just learned it’s not worth doing business.

@SolarEngineering

2 жыл бұрын

Yeah, unfortunately. You are welcome, hope this video will warn people.

@amanofmanyparts9120

2 жыл бұрын

Yup. been there, still waiting for the T-shirt to arrive!

Glad you did this Vid. Prefer if you were more direct - I walked similar road via Alibaba. Neither the Supplier nor the Vendor takes responsibility for corrupt products not financially worth returning. Tried a 2nd Supplier and backed off before giving them my money. Now I'm at point where I refuse to deal with Chinese mentality and really hope for another Country to offer LFP and BMS.

@guysgt5003

2 жыл бұрын

Absolutely correct my friend you are an intelligent person. Thank you for chiming in

@eyeswideshut2800

2 жыл бұрын

Didn't Prowse recoup from Amazon recently on bad cells from China? Shipping has gone up exponentially so bad deal.

@kevinmills5293

2 жыл бұрын

I’ve been burned twice when dealing with Chinese suppliers. I’ve asked for samples from potential suppliers but of course they refuse so I won’t buy any cells from China now. As he says in the video, it’s legal scamming.

@carmichaelmoritz8662

2 жыл бұрын

i bought four brand new 12 volt lead acid batteries for my 48 volt mobility scooter and they lasted one year use before one failed. i could go three days of short travels before a charge was needed. i now bought used headway cells and thats something i will never do again. even at 80 percent life they still only last about ten minutes before they start to drop to the point where the scooter shuts down due to low voltage. and the price of new compared to lead acid , i will stick with lead acid even though they weigh way more. almost 600.00 lost that this poor disabled person will never get back. very disappointed.

@claesmansson9070

Жыл бұрын

Think it s important to fix/compress cells before starting charging on them,even grade a cells will swell 1 mm, the reason for compression is that you should get a 1000 more cycles out of the battery in total.Ray builds cool stuff has made a video on who you should be able to trust of the sellers in china,think her name is Jenny, but you can find the video yourself.

Great video. Thanks for taking time to post it. We're all in this LiFePo4 mess together.

@SolarEngineering

2 жыл бұрын

thanks!

Great job! I have been drilling and tapping my bus bars to hold 8-32 screws coming from underneath. The BMS leads can now fit the little red 18 Gage ring terminals crimped on instead of the way too big ones everybody puts on the cell studs. These were made for larger wire and often the BMS wires have poor contact. Besides, once I tighten the cell studs down, I do not want to disturb them again for any reason. Having a ring terminal in there is a weak spot and will yield over time and create a hot terminal. I'm glad to see that you put the BMS leads on the bus bars too. I have that same kind of Renogy inverter charger not yet installed. Heavy!!! 250 amp Daly, too. My 560ah cells are on a home built ''solar generator'' that I use every day. It was a fun project.

@SolarEngineering

2 жыл бұрын

thanks! you are first noticed extra screws for sensing leads. I'm planning to use this pack to test multiple BMSs and other components. And yes the main reason is not to disturb battery studs every time, since it's really easy to over-torque and strip threads on cells. This Renogy is f... heavy, I need to do some exercises to move it around.

Great job with the video compressing your batteries I’ve seen many not as smooth as the way you’ve done it !

I love the perfectly alligned holes on the new busbars 👍👍👍

@SolarEngineering

2 жыл бұрын

it was huge luck

Thank you for making this experiment 🤩

Nice job. Looks tight. That being said, i just let my cells bloat as they want.

One important point is that, in your first test, the output cables were properly connected to the battery such that all cells will share current equally. In the second test, after the compression and the new bus bars, the output cables were not connected for equal sharing of current between all cells. Connecting them as in the first test would have improved the result of the second test to some degree.

Thanks for sharing, very educational and practical.

@SolarEngineering

2 жыл бұрын

You are welcome Malcolm. I personally would not recommend to compress swollen cells. This video is a pure experiment. I'll follow up on compression in follow up videos.

I think we are just going to have to accept that the chinese vendors of prismatic cells are going to over state the capability of their cells. This has been going on for two plus years and virtually all the vendors do it.

@SolarEngineering

2 жыл бұрын

I think the bigger problem is used cells. I'm "ok" with under-capacity new cells. But I guess these cells were used previously. But unfortunately, it's just a guess.

@ursodermatt8809

2 жыл бұрын

@@SolarEngineering my experience, the seller called himself "honourable" and then sent "A grade brandnew" cells that were second hand.

@peterlindstrom8865

2 жыл бұрын

Just like used car sellers!

2 жыл бұрын

Some cells were stored for long periods and not maintained. They can swell even in storage and they degrade faster if outside the storage voltage and temperature. And the Chinese overstate products performances since the 90s. There are plenty 900000000mAh 18650, sand filled cells on ali/bang/dx/etc

@ursodermatt8809

2 жыл бұрын

@ i doubt very much they keep cells for long periods in storage. they want to sell them as quickly as possible.

Some vendors recommend applying pressure _before_ cells have swollen to get maximum cycle life. Doing it afterwards might be dangerous and will not result in benefit. I never even got an answer if one is allowed to recompress a stack that had been properly compressed in the first place, but then needed a single cell replacement. I think you can book the 8Ah to slight differences between runs and measurement uncertainty.

@SolarEngineering Nice video and I applaud you for testing this. Yes, it is not the most wise thing to do with bulged cells, but it is not that catastrophic. Even if you had used springs there would be some "expert" to find something to tell you it is not good enough. About the refund, there is a trend that only Amazon buys or big youtubers get a refund when they "discover" such cells. I wish you good luck with your cells and refund and hope to see an update video about your situation.

@SolarEngineering

2 жыл бұрын

definitely will post an update if any progress about return/refund.

@CL-yp1bs

Жыл бұрын

@@SolarEngineering You can get refund if you make dispute with aliexpress... it will take a couple of months.. liiokala and varicore are known scammers.. still selling used b stock cells

@SolarEngineering

Жыл бұрын

@@CL-yp1bs I did open claim, but Aliexpress declined refund.

I just ordered some similar to these... Sold as grade A 320 AH. 16 cells delivered for about 500 USD. Shipping should cost most of that. I don't need full capacity but the price was so good to pass up. Excellent video. Thanks for the data. Greg in Hawaii.

@Loolanga

2 жыл бұрын

Hell could you chuck us a link to 16 cells for $500? Even if they're grade b garbage that's an insanely good price.

@YelloJello

2 жыл бұрын

I just received my 105 aH Littokala from AliExpress. 2 x 16 packs. Almost all had slight bulging except 4.

@ForbiddTV

2 жыл бұрын

Hey Greg, any update? Since you seem to have disappeared we aren't quite believing the deal you claim to have gotten.

@gregguithues855

2 жыл бұрын

@@ForbiddTV well thanks for the reminder. No delivery, lying seller, Aliexpress refunded with no fuss.

@gregguithues855

2 жыл бұрын

Btw I bought five sets total 20 batteries. Nicely balanced 3.293 and 3.294 voltages.

I'm so glad that over here in europe a seller has to cover the cost of return shipping.

@Frolleglse

2 жыл бұрын

Are you sure? Is that something new? I had some issues where i also ended up as the looser due to high return shipping cost.

@asArsenic

2 жыл бұрын

@@Frolleglse No, this isn't new. You may be in the position to demand that you be reimbursed for your shipping costs. You shouldn't have had to pay them in the first place.

@asArsenic

2 жыл бұрын

@@Frolleglse Within 2 years the sellar has to repair, replace or refund a defective product at no additional cost to the customer. Prior to six months any defect is assumed to have been present at purchase, afterwards the seller may demand evidence that the product was defective at the time of sale.

@Frolleglse

2 жыл бұрын

@@asArsenic ok. Thanks for the input. I will refer to "EU directives" next time i end up in a bad position.. If a success I guess it will be the first time something good comes out of this EU crap..

@asArsenic

2 жыл бұрын

@@Frolleglse There are a remarkably large number of good things that come from the EU.

Cool vid! Thanks man

@SolarEngineering

2 жыл бұрын

thanks

Thank you for doing the test, interesting but sorry that sellers aren't being honest with you.

@SolarEngineering

2 жыл бұрын

yeah. many people is the same situation, unfortunately

They are supposed to be compressed before they swell not after.

@jasonwarren781

2 жыл бұрын

They came swollen, he didnt cause them to swell

thanks for sharing theia really important and interesting information

@SolarEngineering

2 жыл бұрын

Glad it was helpful!

your brave doing that. I done the same with 'Zippy' branded lifepo4 packs from hobbyking, they were swollen only a little more than what you have, and under compression the ends of the cells exploded...

@NeilBooth

2 жыл бұрын

Are you sure they weren't zippy lipo? Lipo explodes, not lifepo4

@Ra-zor

2 жыл бұрын

@@NeilBooth 100% LifePo4, cells pressurised and ends exploded. LifePo4 still explode, they just don't catch fire, just smoke (quite a bit!).

Tighten the top two bolts tighten more than the bottom. Keeping the top bolts tight shouldn't allow much pressure on the terminals. Keeping the bottom rods little looser would allow for some expansion.....

Regarding swelling and bus bars.. Why not use "soft" bars bended in an upward arc that will flex? Or just short thick cables in arc with a lug at the ends. I remember that cars used to have a flat braided connection on the minus pole down to the chassis that will easily flex.

@gelisob

2 жыл бұрын

would recommend that too, in case of decompression or expansion - you dont want to rip off terminals.

Hi. Great Video, can I please ask if 2 to 3mm Battery Seconds is alot and if it's a concern...

Great job! I believe compression keeps the electrolyte within contact of the most of the internal media. If a battery bloats the electrolyte is no longer in contact with 100% of the media. With out the media in full contact with the electrolyte I would imagine you would not get full capacity. In addition I have seen batteries that have failed and it appears that it was from media drying and separating. Cycling without compression will do both of these things. Therefore in my opinion compression is safer and adds life to the battery. I really do not believe the manufacturers of these batteries really care and say it is not necessary because they really have not done their own testing and are going off info from initial manufacturers knowledge from years ago.

@mickwolf1077

11 ай бұрын

Something would have changed in the cell for it to bloat, likes produce gas maybe? Compression after bloating will increase pressure but still increase electrolyte contact.

Thanks for the interesting video. I was wondering what is the insulation material you use between the cells.

@SolarEngineering

2 жыл бұрын

it's just thick paper.

Thanks

Лучше не заряжать до 3.65в, это максимально допустимое напряжение при котом идет уже деградация и распухание) LiFePo4 можно считать заряженными когда напряжение начинает резко расти, в зависимости от тока это может быть 3.4-3.55в

Super Akku habe auch so was 🤗👌👍

My concern about compressing cells is that it might cause an internal short between the layers of dielectric material inside the cells. They need to be able to expand naturally so that the pressure doesn't turn inward on the insulation layers.

I have the same batteries as you 32 PCS 280Ah 3.2 v i’m going to be linking the batteries together similar to the way you were but in a past video I saw flexible bus bars put less stress on the battery terminals with the very little fluctuation the batteries need do ! It was on KZread a lady did the video check in the amperage in the batteries in the heat on the terminals in the braided busbars perform the best not the rigid copper bus bar ! Hopefully this may help you in any future frustrations you may have but things out working correctly !

When Testing batteries there are many factors. U may find that the ah goes up a little on each of the next 10 cycles. Slow charging and discharge also gets more ah. A few more cycles would be interesting.

@SolarEngineering

2 жыл бұрын

will do another capacity test later

@steveclunn8165

2 жыл бұрын

@@SolarEngineering testing batteries can go on and on. You could uncompress half of them and then do another 10 Cycles and see where that uncompressed half compares to the compressed half.

Maybe I’m late to the party, but was a proper too balance performed? Edit: looks like yes. To rule out improvements from cycling alone, why not perform the test a few more times? I’ve heard these can be “woken up”. What was the deviation at cut off? Also, I’ve been weary to cut the threaded rods that close. Not sure I can recompress if I needed to disassemble. Another pro tip, you can cut soft metals like aluminum and copper with a normal saw. Works great.

@SolarEngineering

2 жыл бұрын

>>Maybe I’m late to the party, but was a proper too balance performed? Edit: looks like yes. yes, top balanced all cells till 3.65V To rule out improvements from cycling alone, why not perform the test a few more times? I’ve heard these can be “woken up”. >> usually cells perform little bit overcapacity while new. What was the deviation at cut off? >> Since discharge rate was very low, all cells were about +-50mV Also, I’ve been weary to cut the threaded rods that close. Not sure I can recompress if I needed to disassemble. >> good point, I have some extra length on other side Another pro tip, you can cut soft metals like aluminum and copper with a normal saw. Works great. >> need to try it, thanks. Also I tried to search how to cut oval whole for studs to allow some play. Do you have any suggestions?

@antonkireev4098

2 жыл бұрын

@@SolarEngineering Я использую несколько надфилей разных размеров для получения необходимого профиля и размера. Медь мягкий металл и легко обрабатывается. Удачи.

Couple questions. Why didn't you arrange the cells with the smaller sized side ? Fixed circular holes can overtension the connector and break them when bloating. Is the compression wo torque measurement ?

@SolarEngineering

2 жыл бұрын

Because I want to test if compressing cells would recover any capacity.

@janosvarga962

2 жыл бұрын

@@SolarEngineering no it won't significantly, but will increase the cycle life of the pack.

Hi Thanks for the video! Is there any update on these cells. Did you continue to use them?

@SolarEngineering

2 ай бұрын

I was using them a few times to record some tests. But mostly it was sitting in the garage.

Hi! I see you used some kind of inductive load in the discharge test. How accurate is your consumption measurement with an inductive load compared to discharging with a resistive load? In my opinion, any cheap consumption meter is not necessarily close to accurate when the consumption takes place with an inductive or capacitive load.

@Mike-01234

6 ай бұрын

If you use the same load for both tests should be the same. He got recycled cells probably see re-lasered QR codes an old one under that plastic top. Compressing a swelled recycled batteries won't fix the problem they are recycled likely been used for streetlights in China what I heard. These companies go around and replace the battery sell it to a 3rd party who puts new plastic on them re-lasers the QR sells them as Grade A batteries to Americans.

This is exactly the same problem auto mfgr are going to have with pouch cells,there is not enough compressive strenght in the housing to keep the plates properly aligned . The cylindrical cells have great strenght to be able to resist the outward pressure, the inner separators provide the containment needed for the vertical expansion. This is like a jelly sandwich when you squeeze the jelly comes out the sides.

@tacticallithium7831

2 жыл бұрын

There are no plates in prismatic or pouch cells.

@firstbigbarney

2 жыл бұрын

@@tacticallithium7831 It may be a foil but it is still a plate. They may be rolled or folded in the case.See kzread.info/dash/bejne/i6Z1m8l9dKXHm8Y.html

@raphofthehills4405

Жыл бұрын

That's why in the Nissan's Leaf battery pack all the cell stacks are sandwiched between metal plates.

I was scammed by Aliexpress also; 300 Ah only have 110 Ah; brand new,big,but only 110Ah and one cell even less; a dispute is going on, and thanks to your video,i refused a return and refund,i want a partial refund; i spent countless hours making videos and photos,all kinds of tests they asked for; the dispute is going on for 2 weeks now, what a effing nightmare; it won't be long now but i have a bad feeling about it; again,thanks for your video; you still lucked out, they have decent Ahs.

@estartermanual

Жыл бұрын

I received 20-30% capacity scrap batteries, the same as your nightmare, 50h spent to only 40% refund

@josepeixoto3384

Жыл бұрын

@@estartermanual Not too bad after all? º.º my UPDATE: after a 2 week battle, i received 187 euros refund, and that had been my sugestion to Aliexpress to end the dispute it is actually easy,time consuming but easy: FIRST thing is to prove with pics and videos that the product is NOT as sdvertised; SECOND thing is to say that (according to Aliexpress policy,READ IT!!) the Seller pays for the shipping to return the items,since he is at fault,not you THIRD, you WARN the seller that the cells and buss bars are now USED, they now bear the marks of the heavy tests he demanded during the dispute,and that you will NOT accept any excuses when he receives the items... º.º you then suggest a reasonable,for both, amount to be refunded if the seller does not pick the Cells up; he won't and you will be refunded.

Seems it might be worth testing individual cells and going back to 1p. 1 cell could be messing up the whole pack.

Yeah, unfortunately its pretty common on Aliexpress to run into those issues. But for the price, its still WAY better than when I buy here in the US. So, if I buy 4 280ah batteries and I pull 260ah, for the price of $400, its still worth it. Just lower your expectations when ordering and you'll see its value.

@alexgunner1882

Жыл бұрын

Not anymore you don't. It's double now :(

So have u bought grade A cells and tested them to see if they're pulling capacity?

@SolarEngineering

2 жыл бұрын

I did purchase grade A cells before, my bigger bank contains only grade A: kzread.info/dash/bejne/hHaTscFugNPcZ8o.html

I got 4 280ah cells on alliexpress. was lucky and non are bulging. still need to perform a capacity test though. it's a roll of the dice with alliexpress. probably wounldn't chance ordering more than 4 though

Can anyne please explain? What is the point of compressing, if in this case eventually it will most likely lead to blowout safety valve on the top of the cell (instead of inflating the cell)?

Get ready to get attacked by the internet experts lol

@SolarEngineering

2 жыл бұрын

haha, bracing myself :)

I did order a set of four 280 Ah batteries from this same company ( same ali store) earlier this year and they tested out at 283+ . It makes me wonder if they just fill in orders with pure crap if they don't have good stock.

@SolarEngineering

2 жыл бұрын

I think they build reputation and now is a time to cash-out.

@5nowChain5

10 ай бұрын

they have mixed cells in stock, its random what you get. looks like he would up with 240Ah on average. if tested individually there might be higher or lower Ah cell in the group

Hi there, what are the dimensions of your custom bus bars? Especially the thickness. What would you recommend for a 16S 280AH system 1C. Thank you.

@SolarEngineering

Жыл бұрын

I think I got 0.125" x 0.75" Copper Rectangle Bar 110-H02. purchased from here: www.onlinemetals.com/en/buy/copper-rectangle-bar

Will the battery explode when you compress it?, maybe now but maybe month to come. I got some grade B cell too but I use flexible buss bar.

@kimmer6

2 жыл бұрын

No, they won't explode. When they are overcharged, they create a gas and that causes the swelling. The blue plastic oval on top of the cell protects a scored aluminum burst disc which is set to relieve the gas pressure. The cells can swell about 3/4 to an inch in width before the little burst disc operates. Ask me how I know.......

@w3bb0y

2 жыл бұрын

What flexible bus bars are you using?

@pierreqiu8147

2 жыл бұрын

@@kimmer6 ok thank you, then should I leave the battery uncompressed or compress

@kimmer6

2 жыл бұрын

@@pierreqiu8147 I assembled mine in 2 packs of 4 cells, 8 long, 4S 12.8 volts. They fit tightly inside a wooden box. While I was testing them, I wrapped each pack of 4 cells in 2 layers of Fiberfix 10X tape. That is an incredibly strong tape with glass fibers embedded within. Then both sets of 4 cells went into a wooden box that I made and the free space on one end was shimmed tightly with a 1mm thick Bakelite plate the size of the battery side. The battery has been successfully operating since May 2021 and discharges to about 80% capacity by nightfall and recharges at about 26 amps when the sun hits the panels. The bus bars are the solid ones that came with the cells. There are times when I discharge the cells at 160 amps and recharge them from a generator at 75 amps. I have seen no problems with the cells in several months. I believe the excess gas that causes cell swelling happens only at charging at more than 3.65 volts. I do not think there is much gas production at all with normal operating voltages. If I make another battery, I will use the 10X tape to bind them together. They were designed to be compressed inside electric vehicle battery cases. With solid bus bars I would absolutely compress them to prevent looseness and hot spots at the terminals. I'm sorry that I did not take photos of the assembly of the unit. The battery box is all but hidden. The 10X tape link: www.amazon.com/FiberFix-Stonger-Bearing-Untearable-Resistant/dp/B01H2SH92Y/ref=asc_df_B01H2SH92Y?tag=bingshoppinga-20&linkCode=df0&hvadid=80401840125272&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584001418376754&psc=1

@pierreqiu8147

2 жыл бұрын

@@kimmer6 hi, thks for all those useful information,👍👍👍👍👍👍

What kind of inverter are you using for the 560AH per battery now ? I’ve been told by POWERMR inverters to get MPPT stronger inverter then GVW is so post to be a weaker inverter !

@SolarEngineering

Жыл бұрын

Renogy 3000W amzn.to/3OTQ5Kw

It sounds silly but I always had a hard time pinpointing drill points on a bus bar ... I have no idea why I never thought to do it your way. Duh. hehehehe. Thanks!

@SolarEngineering

2 жыл бұрын

we are all learning

Hi, i just bought 16 brand new grade A Eve 304 cells. I want to have the same setup as you but two rows of 8 for 16s block for 48v system. What Nm should I tighten up the nuts on the 4 threaded rods to meet Eves recommendation. They dont specify how to do it. Thanks so much.

@peter572

Ай бұрын

I think the specs recommend 300Kgf. Too tight is as bad as no-compression. I am thinking of adding a spring to the rods or some soft material in between the cells. Any ideas?

What are the insulation sheets/plates do you use between the cells?

@SolarEngineering

2 жыл бұрын

just thick paper

I always see these with the terminals facing up. could these cells be rotated 90 degrees toward the camera direction.

@SolarEngineering

Жыл бұрын

It's better to check with manufacturer. cells that I'm using can be positioned as you described.

The CCP says thanks for buying our used/waste batteries - keep the cash coming

@SolarEngineering

2 жыл бұрын

yes, it's a nice way to recycle used batteries.

@kumarhimar3683

11 ай бұрын

your house is full of made in china dude.... mine your own business😂

I wouldn't try to compress bulging cells. The pressure has to go somewhere. Your batteries so do as you want, but would advise releasing that pressure. Better to have a working cell with less capacity than blown cells.

@ursodermatt8809

2 жыл бұрын

well, he just did, and there was no explosion, no releasing pressure.

@kevinmills5293

2 жыл бұрын

Has anyone actually had the pressure valve blow? I’ve not seen anything on KZread.

@ursodermatt8809

2 жыл бұрын

@@kevinmills5293 i have never seen it either, except when they deliberately over charged the cell.

TG found this video b4 buying those, now it makes sense why they are selling these free shipping...

@SolarEngineering

2 жыл бұрын

I feel like the seller built reputation by selling good cells, and now they just started to scam people.

I'd of thought you would reduce their life compressing after expansion. I payed way more money to get them locally just because of this potential problem but I rely on mine 24/7 for all my power so...

So you got 240-260 Ah out of 280 Ah cells? Did you pay for grade A or lower batteries? Did the price reflect the 10% capacity loss that you have documented? Was the discharge test conducted at room temp, around 20-25 Celcius? As we all know, low temps reduce capacity.

Compression does not change the capacity - why should it? Its not working like a capacitor where the distance of electrodes playes a role :-)

you should also top balance and see the result.also if your gonna compress the cell you should atleast have clearance on your bus bar as it will tear those contact.

@SolarEngineering

2 жыл бұрын

cells were balanced. thanks for the suggestion.

Be careful, cells increase their volume during charging, so you can't do it like that. 1Kg per Ah is a good value so this pack need 300Kg so 75 Kg per screw. You need some springs to compensate for volume increase during charging. Compression should be done from the begining off cell life to avoid dentritic building between electrods and then wollen cells. These cells are already used.

🤗👍 Super danke 👍👍🤗

@SolarEngineering

Жыл бұрын

you are welcome

You should do the compressed one first? the first one swol the cells and ruinds them?

Are still these cells working ?

Ordering direct from China is just a way of gambling. It's not if you will lose, its do you have any chance of winning? They hold the buyer hostage with the high shipping costs. Especially when even if you send it back they could still not pay you and then you would really lose.

Hello. I bought 16 EVE brand 280ah cells to make a 48v 280ah battery pack. I also bought JK BMS, it also has other connection equipment. However, during the final assembly, I could not decide what I should put as an insulator between the cells. They install epoxy sheets in commercial products. I don't have any epoxy sheets. I am thinking of using corrugated (cardboard / cardboard sheet etc.) for both insulator and heat ventilation, but I do not know if there is a fire risk in this. As long as there is no arc or heated cable, I do not think there will be an ignition due to cell temperature. Because if that degree of heat is released, the cell is already dead. WHAT IS YOUR ADVICE?

Hi what the recommended charge level for 12v life po4 ? From my research its 3.65 per cell.Whats the maximum discharge voltage for the batteries to get maximum cycles from them? I bought 310ah and they are very bloated … i balanced them out and charged each cell to 3.6 and now want to discharge them but unsure to what level its reccomended to do so, can you advice?

@SolarEngineering

Жыл бұрын

14V should be good enough to charge battery fast and keep some safe margin.

It is my understanding that you have to compress the cells once they are fully charged, and not to compress and then charge them. Also, it's best to use springs to offer resistence and not completely block their expansion and retraction. Finally you can't improve the battery by this method, but you add longevity to the cells, which, off course, works best for cells that arent bloated already.

@gymkhanadog

2 жыл бұрын

It was my understanding that it depends on the type of cell and if the manufacturer calls for _compression_ or simple fixturing. These bare cells often have a +/- dimension for different SOC.

@kandkob

2 жыл бұрын

Why compress when fully charged? is that too late, cells will have swollen?

@PablumMcDump

2 жыл бұрын

@@kandkob perhaps it's like the advice to buy shoes when your feet are swollen? Calibrate based upon the high side of the normal cycle.

@rafaelbronzon85

2 жыл бұрын

@@kandkob It's the nature of the prismatic cell to expand and contract. You don't want to stop that, you want to control it a bit. That's why you can use springs to offer resistance to this movement. That makes more sense when you have brand new cells, though. To tight already swollen cells like that risks blowing the overpressure valve and killings the cells.

@bradley3549

2 жыл бұрын

That is contrary to what I've seen. You want to fix them at their lowest state. You're right that you don't want to completely stop movement, but it does seem that controlling the plane that the growth occurs in is the reason the cell life seems to improve. You don't want growth perpendicular to the jelly roll layers, you want the growth to occur parallel to the layers. This is one area cylindrical cells absolutely excel. Prismatic cells don't have the benefit of geometry, so they need mechanical help to maximize longevity.

I think you have to add the compression before the cells swell

Have you tried ordering through Alibaba and not aliexpress? I notice that your cells are out of balance by quite a lot. Is the bms not balancing them well? While one cell hit 2.5, the other were at 2.7. If they get balanced properly, you should be able to get 490~500 ah from them. Just a guess. Thank you for the video.

@SolarEngineering

2 жыл бұрын

I haven't as I understand it's same company with same customer support.

@asderven

2 жыл бұрын

​ @SolarEngineering the company behind them is the same. But Aliexpress is more retail, while alibaba is more wholesale and actual factories that take your order directly. CATL or BYD won't be there. Unlikely to find EVE either, but you can find good companies who sell cells on wholesale and can provide you with balanced and grade A cells most likely. As with any such platform, have to research the seller more than the product :D. Bansen tech, deligreen and a few more like that are very reputable. They also provide videos and pictures of your order (that is not proof enough, things can always get mixed up). But way better than using aliexpress in my opinion. I personally haven't tried them yet. I will be ordering once I get my import license in my country. A thought for the next time.

@SolarEngineering

2 жыл бұрын

@@asderven interesting, thank you for the information. Need to do research about it, curious to hear people who placed orders on Alibaba.

@asderven

2 жыл бұрын

@@SolarEngineering Not sure if Andy from offgrid solar used them. People on secondlife forum and diysolar forum have reviews of different sellers they have used from alibaba. There are a few lesser know lifepo4 battery buiders (diy) who have used them. Mostly good experiences with communication and patience.

I wonder if the slight increase was due to charging and discharging rather than compression? If you could be bothered to charge them again and check the capacity without compression?

@SolarEngineering

2 жыл бұрын

will try

how they work after 1 year of use?

@SolarEngineering

Жыл бұрын

I'm not using them.

I had the same problem with Aliexpress they sent me grade b cells even though the ad said grade a. The only options I was offered were a discount or send it back at my own expense. This is definitely cheating for me but what can you do? First of all, I gave the app and the seller a bad rating. Then I resold the cells as grade b and luckily I got plus minus zero with the discount.

@SolarEngineering

2 жыл бұрын

I did the same - 1 star rating for the product.

In order to keep them from potentially leaking in the future, would you recommend putting them end to end instead of side to side?

@SolarEngineering

2 жыл бұрын

I'd recommend fixing cells to remove any movement and remove stress from busbars. Going to build a pack soon and record it.

Do LiFePO4 batteries need a BMS?

@SolarEngineering

2 жыл бұрын

yes, overcharge/discharge could reduce cell life significantly.

Where you get that copper flat bar from ?

@SolarEngineering

Жыл бұрын

purchased copper from www.onlinemetals.com/

For the price these cells are a steal. I got lucky I guess. Mine look brand new and the sides are actually a little concave. 8 x 280AH, same as your. Paid under $870 USD ($1200 AUD) shipped my door in australia. $110/KWH is a bargain even if they fall well short of their claims. I'm a remote power system sparky from way back and used to do all this with lead acid, which even now are still over 3 the cost per watt. And this is China dude. Ya pays ya money and takes ya chances. You know that. ;)

@SolarEngineering

2 жыл бұрын

I understand what you are meaning, but I would like to get what I pay for. Otherwise, it's just a game without rules, where the buyer is going to lose.

Can you post a link to that ammeter you were using to conduct the test?

@SolarEngineering

2 жыл бұрын

here you go: amzn.to/3F0PXTZ

@J.DiPietro

2 жыл бұрын

@@SolarEngineering thanks. I picked one up and I love it. I discharged the batteries completely and then charged it and found my batteries to have a higher than rated capacity (294Ah vs 280). I realize that the 280 would be at 280 amp discharge but i don't really have huge draws like that so it seems more realistic for my usage.

@SolarEngineering

2 жыл бұрын

@@J.DiPietro wow, you are lucky! glad to hear that you got good quality cells.

What do you do use for insulation between cell?

@SolarEngineering

2 жыл бұрын

just thick paper.

My battery setup is 200 ah plastic encased prismatic cells and no compression they are just put in a plastic box and I use a 200 amp Daly BMS too plus renogy 500 amp battery monitor

What I'm not getting is: if it costs 1.1k to send it, how do they send it to you? it must cost them as well right?

@SolarEngineering

2 жыл бұрын

I think China postage is a lot cheaper, I can buy something from China for $2. If I ship same weight back to China from US it would cost $5.

@raphofthehills4405

Жыл бұрын

Shipping batteries is very expensive bc they are classified as hazardous material. Many oversea sellers don't declare them as such and therefore pay regular low prices.

I have a 2p 4s 400 ah setup here in my camper van

De cuantos amperios es el bms

For the bus bars I recommend oval shaped holes instead of the round ones that fit almost exactely to the thread. With almost no space for expansion the tension/force will damage the housing of the batteries. At the same time, I don't think it is wise to compress battery cells, no matter what kind of technology is involved. Lead acid cell can also swell, suppose you would do the same ?! This is a blue print for disaster...

@MatthewN8OHU

2 жыл бұрын

I would agree with you for Grade B cells, but let's not forget that the battery cell manufacturers actually do recommend it to increase the cycle life of the cells. I think that as long as you don't go to extremes with the pressure when compressing them, you're going to be fine.

@jmacd8817

2 жыл бұрын

The cell manufacturers recommend compression. Eve batteries are give 2500 cycles lifespan uncompressed, and 3500 when compressed. It seems counter intuitive, but that's what I've seen

@jmacd8817

2 жыл бұрын

@@MatthewN8OHU beat me by 14 seconds! lol

@SolarEngineering

2 жыл бұрын

could you give me an idea of how to cut oval holes? I was thinking about this, but cannot get an idea of how to do it with standard tools. Thanks.

@Sylvan_dB

2 жыл бұрын

@@SolarEngineering two holes drilled adjacent and a little file to smooth the ridges between.

Интересное решение против вздутия ячеек. Они реально дуются при зарядке :-( Надо будет так же на фанеру и шпильки посадить, возможно лучше перед этим разрядить каждую ячейку отдельно до 2.5В, тогда мне кажется проще корпус выпрямить.

@SolarEngineering

2 жыл бұрын

я в итоге добавил сверху и снизу ячейки проставку в 1мм, и затянул шпильками. 1мм позволит ячейке в центре расширяться при заряде/разряде но при этом ячейки зафиксированы и нет нагрузки на контакты там где басбары стоят.

@ibrownbear6531

2 жыл бұрын

@@SolarEngineering а шпильки какие, 6-8 мм?

@SolarEngineering

2 жыл бұрын

@@ibrownbear6531 6мм, ужали без проблем.

@ibrownbear6531

2 жыл бұрын

@@SolarEngineering Спасибо

Yes Akb LiFePo4 🔋 ⚡ 👍

Hello, how did the batteries do within the last 12 Months?

@SolarEngineering

Жыл бұрын

I don't use these cells.

You could have left the length on the threaded rod and tightened them from the other end...

@SolarEngineering

2 жыл бұрын

don't want to have sharp rods sticking too much.

hi i think those busbars not avaible for 500A BMS

Compression makes sense over many cycles. It is not possible to see this effect in one cycle. The difference of a few Ah is not the point. Due to the new datasheet from 2019 (website: off grid garage) you can see the advantage over thousands of cycles. The main part is not the central force of 3000N, but the right pressure ! The gap between the cells should filled - thin layer of epoxy for example, otherwise this is not effective and would cause damage.

there are two things I won't buy from AliExpress one of them is a cell phone and the other one is use large batteries or any batteries in my experience. also anything that requires you to have it reviewed by customs.

950$ for 8 cells of 245Ah is not a bad price. It's cost you 0.49$/Ah, and the average price is 0.53$/Ah.

Do you a link for that copper bar?

@SolarEngineering

2 жыл бұрын

buying from this store: www.onlinemetals.com/en/buy/copper-rectangle-bar

@dave9447

2 жыл бұрын

@@SolarEngineering Cool thanks

Do you really think compressing has any effect on capacity?

@bloodcarver913

Жыл бұрын

Nope. Only on longevity.

If I buy supercheap aliexpress cells, I will expect them to have just 80% of their rated capacity, so just order more than you need, but it's still much cheaper than buying grade A cells

Is it possible to connect 32 cells With 16 cells in two parallel groups That is, summing all two cells parallel to each other Complete with a 51 volt system Any breath, 51 volts Note with the use of one bms

@SolarEngineering

2 жыл бұрын

yes, checkout my latest video. I have battery 3P16S

@munirzangana3594

2 жыл бұрын

@@SolarEngineering Thank you for the information But why don't we notice it a lot, especially in its great capabilities, unlike the Package Parallel separately?

@SolarEngineering

2 жыл бұрын

@@munirzangana3594 almost every EV has cells in parallel.

To be clear: the manufacturer specifies more cycles, not a larger capacity of compressed batteries. So, the experiment is interesting, but neither proves nor rejects the effectiveness of compression.

hi, what is significate of grade b??

@SolarEngineering

2 жыл бұрын

Grade A cells - it's a new cell, never been used, every cell has a unique ID number and capacity is equal or more than in specs. Grade B (or not A) - cells that potentially were used or cells that have defects and/or under rated capacity and unique number were destroyed.

How many amps is that daly bms?

@SolarEngineering

Жыл бұрын

500A

@boblazarrss

Жыл бұрын

@@SolarEngineering thanks I just ordered a 250 smart bms im just wondering how big it will be

Alternative title: how to trigger the overpressure release valve 100% on grade B cells

@SolarEngineering

2 жыл бұрын

)) good one

@kimmer6

2 жыл бұрын

@@SolarEngineering Can you please tell me if my Grade A cells look bloated? See burst discs...... 2 of 4 gone. kzread.info/dash/bejne/fomcrc-ahM3ZadI.html

@SolarEngineering

2 жыл бұрын

@@kimmer6 😂 just a little bit, what happened to the cells?

@SolarEngineering

2 жыл бұрын

ah, nm, read the description.

@kimmer6

2 жыл бұрын

@@SolarEngineering My brand new power supply arrived defective. It did not hold the voltage setpoint. It ran for a week top balancing 12 cells but made little progress. I disconnected 8 cells and put the leads on 4 cells. This happened overnight. The replacement power supply works as it should. Its an expensive mistake.

Copper on the aluminum terminals will cause galvanic corrosion