Dagoth Ur Does Solar
Solar Enthusiast
Could I ask why specifically it is that you need to buy from Aliexpress though?
Aliexpress is pretty much the place I'd go to if I specifically wanted to buy crappy, probably-a-scam batteries/components.
Aliexpress 24V 100AH battery horrible internal resistance.
- Thread starter Luk88
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Could I ask why specifically it is that you need to buy from Aliexpress though?
Aliexpress is pretty much the place I'd go to if I specifically wanted to buy crappy, probably-a-scam batteries/components.
Brucey
Solar Wizard
Well you did deliberately choose the cheapest unit on AliExpress. If you can step up to the Amazon tier then there's a large amount of proven batteries available, hard to beat two ecoworthy 12V 280Ah in series for 7.5 kWh at $1000:
As already mentioned you should name the battery and store bought from. Aliexpress is simply a market place like Ebay.
I do agree that the majority of lowest cost batteries you will find are not great for meeting ratings. However one should do a cost analysis between what you pay and get from all items. Cheap lead acid batteries are just as likely to disappoint as cheap Li. In some case I found them much worse in terms of price per ah and longevity.
I have been pleased so far with my dead cheap Littokalas (oldest one is 1.5 years now) shipped from China from a recognized store (not one of those that is just numbers). They have out performed similar rated low cost deep cycle lead acid. But I had low expectations and never worried about internal resistance measurements.
As I already said I will name the store once I have no more doubt he knows about it and I've got all the supporting "evidence" done (pictures, videos). You can go to Aliexpress, put in "lifepo4 battery 24v 100ah" select shipping under 15 days to any EU country and you'll see all these stores with no internal resistance numbers or very high internal resistance numbers.
Litokalla is not amongst them. All their stuff is shipping from China now.
However, I wonder, can one call the stores that openly say they sell 200mOhm batteries scammers? I think they prey on people not noticing it, but it is a completely different, much lesser grade of scam than selling 50ah battery as 100ah. This guy has sent me the spec sheet for the battery where it says internal resistance is up to half an ohm (500mOhm) and I stupidly assumed it is a mistake (the battery was already on its way to me at the time, but I could've declined delivery).
Stores that don't give you this spec and then do the same is another matter.
I've been very happy with my very cheap cell purchases. Also with lots of other "cheap" things including my cheap lead acid, a lot of my electronic equipment and tools etc. Cheap doesn't have to be bad at all. It often is, but not always.
I have only head good things about Litokalla. So the below is in general.
With batteries, you may say "you don't worry about internal resistance measurements" and whether it will really matter to you or not depends on the type of load you plan on using. If all you want to power is a 100W terrarium heater so your lizzard doesn't get cold during a power outage you'll not notice any problems even at 200mOhm (24V). But try running a 1kW device and instead of slightly derating the capacity because you're doing a 0.5C discharge while the cell was rated at 0.2C you get 20% of the capacity because there is 3V of voltage drop so your inverter cuts off with 70% of juice left in the cell.
That's why horrible internal resistance numbers matter. It is not an abstract number to put on a sticker. It is a measure of what current you can get out of your cell while it is being discharged.
Also, on the subject of my battery. I've completed a full 6A discharge to 21V. It measured 71AH or 1828wH. This is significantly less than 0.2C it is supposed to be rated at.
After it cut off, the battery recovered to 22.5V. If the internal resistance was good I'm pretty sure it'd be 100ah.
Here's during the test. You can see 200mOhm measurements. Cables add 57mOhm to it so the battery is really about 150mOhm
Oh and before anyone says you measure internal resistance at full charge, lifepo batteries have pretty flat internal resistance during discharge. It is slightly higher at the very top and bottom.
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Sorry, I missed your two posts. I'm replying now.
Why Aliexpress specifically and not amazon/Ebay? Because I like the interface, the good communication with the sellers, good prices, and the fact they process refunds in minutes if both parties agree. Also it seems that's the only place that has 24v 100ah batteries around here at reasonable prices you don't have to wait 45 days for.
Aliexpress is a market. There are better or worse sellers. I've been buying stuff there, including the cheapest stuff since the beginning of it and I have to tell you I never saw such a concentration of scammers in any other field as in ready made 12/24v batteries(maybe early on in inverters). This is why this thread exists. To tell people about this scam I never heard about. Everyone knows about "half capacity scam". I never before heard about "no ability to push amps but good capacity" scam.
Seriously. Step up to amazon. I don't consider any of eBay, amazon, Aliexpress,any different. They are all one tier above temu, shopify, benggood etc. But amongst themselves they are equal.
Shipping a battery like that is going to cost more than its worth from the US, Amazon knows that and they do even make it available in my region. Then add 23% VAT and it makes zero sense. They're getting better with logistics. I can order small items and get them from the US in a couple of days. But not a 30kg battery.
Also I'm not looking for a 280ah battery. I have plenty of sources of these. I even recently bought 16 280ah cells shipped in 3 days(on Aliexpress, they are great cells BTW) I'm specifically looking for 24v 100ah. At the time I bought this battery it was the only one in stock. Yes 10 others were listed as having "EU stock", but every one of these sellers replied no stock when I asked them. Yesterday, another one restocked. So I ordered that one too. I'll test it and if it's bad I'll send it back for free. (I'll write about it too).
Do you think Amazon or eBay are any different? I don't. I buy on all 3 and often the same item and same sellers are on all of them. An exception are items I can order from the US through Amazon at very good shipping prices. But this doesn't apply to huge bulky items like batteries.
Why Aliexpress specifically and not amazon/Ebay? Because I like the interface, the good communication with the sellers, good prices, and the fact they process refunds in minutes if both parties agree. Also it seems that's the only place that has 24v 100ah batteries around here at reasonable prices you don't have to wait 45 days for.
Aliexpress is a market. There are better or worse sellers. I've been buying stuff there, including the cheapest stuff since the beginning of it and I have to tell you I never saw such a concentration of scammers in any other field as in ready made 12/24v batteries(maybe early on in inverters). This is why this thread exists. To tell people about this scam I never heard about. Everyone knows about "half capacity scam". I never before heard about "no ability to push amps but good capacity" scam.
Because it was the only one in stock.
Seriously. Step up to amazon. I don't consider any of eBay, amazon, Aliexpress,any different. They are all one tier above temu, shopify, benggood etc. But amongst themselves they are equal. There are two issues with this.
Shipping a battery like that is going to cost more than its worth from the US, Amazon knows that and they do even make it available in my region. Then add 23% VAT and it makes zero sense. They're getting better with logistics. I can order small items and get them from the US in a couple of days. But not a 30kg battery.
Also I'm not looking for a 280ah battery. I have plenty of sources of these. I even recently bought 16 280ah cells shipped in 3 days(on Aliexpress, they are great cells BTW) I'm specifically looking for 24v 100ah. At the time I bought this battery it was the only one in stock. Yes 10 others were listed as having "EU stock", but every one of these sellers replied no stock when I asked them. Yesterday, another one restocked. So I ordered that one too. I'll test it and if it's bad I'll send it back for free. (I'll write about it too).
One thing to add. This has absolutely nothing to do with the AC internal resistance. I measured this battery that has horrible DC internal resistance of 200mOhm and it measures only 14mOhm AC internal resistance. For comparison, my 280ah cells measure 0.1~0.08miliohm.
Ok, further development... The battery in question is being sent back. There will be pictures and more info once everything concludes.
In the meantime I bought a more expensive battery reviewed multiple times on YouTube. Also from a Chinese seller, but on a local portal (not Aliexpress). This is the Kepworth branded battery. And I'm very pleased to say it has correct DC internal resistance!
I also tested capacity at 1C and I got about ~2350Wh 91Ah(rated at 2560Wh 100Ah) by using an amp meter and a clock, which is perfectly fine as I read lifepo batteries at 1C are showing 90%-95% of their capacity.
Then I did a low C test with my 180W dl24 tester and this showed exact same result.
WTF?
Not another one...
This was at 10C (Celsius) I have found charts which show diminished capacity up to 10% at 10C but for 1C discharge. Not at 0.05C.
So, I'd love to hear from anyone who tested lots of batteries with dl24. Is this a fault of the meter? Wires are exactly 58mOhm so there was about 27Wh of lost energy there. Any other ideas, other than again I have got a battery that's not meeting it's specs?
In the meantime I bought a more expensive battery reviewed multiple times on YouTube. Also from a Chinese seller, but on a local portal (not Aliexpress). This is the Kepworth branded battery. And I'm very pleased to say it has correct DC internal resistance!
I also tested capacity at 1C and I got about ~2350Wh 91Ah(rated at 2560Wh 100Ah) by using an amp meter and a clock, which is perfectly fine as I read lifepo batteries at 1C are showing 90%-95% of their capacity.
Then I did a low C test with my 180W dl24 tester and this showed exact same result.
WTF?
Not another one...This was at 10C (Celsius) I have found charts which show diminished capacity up to 10% at 10C but for 1C discharge. Not at 0.05C.
So, I'd love to hear from anyone who tested lots of batteries with dl24. Is this a fault of the meter? Wires are exactly 58mOhm so there was about 27Wh of lost energy there. Any other ideas, other than again I have got a battery that's not meeting it's specs?
Brucey
Solar Wizard
Can you use ring terminals instead of the alligator clips?
How did you do the initial charge?
How did you do the initial charge?
Brucey
Solar Wizard
Kepworth has been discussed in the cheap online deals forum, looks like search might be down right now. I think someone tried their 12V 300Ah model.
I'd be vary of Liitokala products also. They are well known for selling counterfeit or repurposed Panasonic 18650 Cells for example.
I'd rate Liitokala batteries B-grade at best, sketchy but usually "close enough" to rated capacity.
btw the correct spelling is "Liitokala" that means literally "flying fish" in Finnish. For some reason they have have picked their brand name from the least known, smallest and most obscure language on earth.
You see on the picture I'm using properly torqued copper lugs (clean) onto which these aligator clips are grabbed. Total resistance of both of these connections and the wires is on the order of 50mOhm while I'm using 6A. 0.36V drop exactly. As I mentioned before this amounts to ~30Wh. Nowhere near the 200Wh we miss.
What I can make better is to make a separate set of voltage detection cables to take even this 0.36V drop out (dl24 has a provision for this).
I charged it with an inverter set at 50A and 29.0V (connected with 70mm2 cables with crimped lugs) when it reached 29V the current was dropping. Once it dropped to zero the inverter cur off charging. Then the inverter was switched off and the battery was left for few hours to let the voltage drop to 27.3V.
Then the test commenced.
Indeed, also there are a number of youtube videos showing the inside of the battery.
Oh boy... And here I thought, heck, if everyone scams maybe ill buy from them and swallow the 55 day wait. Guess not. Also I found mentions of "pregnant" batteries in their reviews on Aliexpress. I think most of these sellers. Litokala, PWOD (and his 6 shops under different names), Deligreen, Spanish Lithium battery store etc. Are all the same. If they have good batteries, you get good batteries. If they have shit batteries, they still sell them hoping for the best. How else can you explain me getting very nice batteries and a week later complete crap from the same seller?I'd be vary of Liitokala products also. They are well known for selling counterfeit or repurposed Panasonic 18650 Cells for example.
I'd rate Liitokala batteries B-grade at best, sketchy but usually "close enough" to rated capacity.
btw the correct spelling is "Liitokala" that means literally "flying fish" in Finnish. For some reason they have have picked their brand name from the least known, smallest and most obscure language on earth.
I guess you can't really trust anyone. That's one of the reasons I only buy from sellers that have product in the EU. I'd rather find out I've been had 2 weeks in than 2 months in.
However, I have a cautionary tale for anyone here in the EU thinking if you buy batteries that have free returns and you want to return within the 14 day "no reason needed" time period you'll actually be able to do this with cells. Why not?
Well, because when you request a free return Ali generates a single shipping label. Your cells will always (if you both more than 4) arrive in multiple 25kg+ boxes. Good luck returning them on a single shipping label. And you're not allowed to return at your own cost to Aliexpress local warehouse.
I currently have a case open with Ali like this. They accepted my return and full refund, but provided just one shipping label for two 25kg boxes (while the courier they use has a max of 30kg). Well see how this gets resolved. Just a month ago the EU commission started an investigation against Ali for non compliance to certain rules (including making it easy to make returns on some items). I hope they took notice and will resolve this by either supplying another label or giving me an address where I can post them at my expense (I could accept that free return postage covers only 1 parcel as long as it goes to a warehouse in the EU not China).
DPC
Solar Enthusiast
btw the correct spelling is "Liitokala" that means literally "flying fish" in Finnish. For some reason they have have picked their brand name from the least known, smallest and most obscure language on earth.
I learned some Fin words from local kids growing up.
One that sticks in my mind translates to "excrement head"
Oh the wonders of multiculturalism in the modern age lol.
Ok, running it again... Well see tomorrow, but I'm not having high hopes.
Also, other than making new cables with proper sense wires I verified it is calibrated correctly voltage and current.
Yes, these are 4mm2 PV wires. The lugs going the other direction are an extra HP voltage meter.
Also, other than making new cables with proper sense wires I verified it is calibrated correctly voltage and current.
Yes, these are 4mm2 PV wires. The lugs going the other direction are an extra HP voltage meter.
MisterSandals
Participation Medalist
What is this? Is that for an external load?
I have the same tester and my understanding was that it messed up the readings of the discharge test as that load was unknown and not counted. I could be mistaken.
I have the same tester and my understanding was that it messed up the readings of the discharge test as that load was unknown and not counted. I could be mistaken.
Problem with these sealed "mystery boxes" is that it is very difficult to know if the cells have reached balance.
"mystery boxes" can also have varying quality of cells that have slightly different self-discharge rate and after sitting 1 year in warehouse one of the cells could be at 20% lower SOC.
Brucey
Solar Wizard
Yup for a new battery it's good to let it sit at float to let it balance, from a long time napping in a warehouse.
Nope, computer, for data logging. Pretty graphs etc.
How is "long time"? A day, a couple of days? I have about 10 days left to decide if it's worth keeping.
Graphs like this. Sadly the old laptop I have in the workshop decided to crash so I only have the latter part of the previous test, but still it is interesting to see. The last test was run as constant current. This time I'm running co stany power So hopefully it will complete sooner.
Also I think it is possible the cells are out of balance, because today when I tried to top it fully up with a power supply it cut off at 28.9V. So at least one cell reached 3.65 for the BMS to cut off. If so and one cell is 0.15V lower can this explain 10% lower capacity? I'm not sure.
Also I think it is possible the cells are out of balance, because today when I tried to top it fully up with a power supply it cut off at 28.9V. So at least one cell reached 3.65 for the BMS to cut off. If so and one cell is 0.15V lower can this explain 10% lower capacity? I'm not sure.
You could have 7 cells at 3.65 and one cell at 3.35v.
3.35v cell voltage during charge can be anything above 10%soc
OK, let's say this is indeed the case. How do I resolve this without access to the pack and no active balancer? I imagine by keeping the battery at float voltage of 3.4 per cell or 27.2V but for how long?
Would you say, if indeed there is imbalance I should see more current consumption at float voltage as the only cell that is below tries to get charged.
How does charging of the cell that is at much lower voltage work? Is it even possible to equalise such a battery?
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