Chinese Batteries

[rffffffff]

I've been digging into this a bit lately. There's a group buy on diysolarforum right now through a member there, quoted roughly $97 per cell shipped to me in NM. (280ah 3.2v)

If you look at will prouse on YouTube he brought a set and tested them and they hit rated capacity. The guy on the forum told me they could capacity test your specific cells for an extra $5 each when you buy them but many of the diysolar people are getting rated capacity from theirs. I'm thinking of making a 2p8s pack for my house first and then an 8s pack for my bus.

The price is cheaper than lead acid at this point, it's hard to not at least give it a shot given the reviews they get and the history on the other forum.

[john61ct]

People citing BB and Dakota

the quality if their cells is a complete unknown

and likely to vary greatly from year to year.

Rely on the warranty maybe the companies will stick around ling enough, if it turns out to be a low enough return rate.

Originally Posted by PNW_Steve

If you order from Chinese manufacturers insist that they include customs/duty and shipping in the price.

Shipping yes, but no one can predict duty, that is a complete wildcard into the US anyway likely many countries depends what the inspector (if any) had for breakfast, and

always the buyer is responsible.

So far have not heard of any USian getting hit on sets under a few grand

and maybe now less likely in the new administration.

[john61ct]

90% of rated capacity, if measured at 0.1C or lower

is a **terrible** result, marker of shoddy maker for sure.

On the big very reputable makers' cells, 4-8% above rated is the norm.

One batch of 180Ah Winstons I got measured at ~12% over, but that was back about 15 years ago

[rffffffff]

I think the us marketing companies are buying cells in volume and likely testing and matching them and warrantying them and selling them for double cost most likely, which seems inline with what we know of the cost of raw cells. If you're willing to run the risk of a bad cell or two, build it yourself with the r and d of the others in forums and not have much of a warranty you can have a cheap battery... if you need support buying retail makes sense, but it depends on each individual.

Customs stuff has not come up in any forum that I have read, no one has been bothered by that to my knowledge, and the group buy insulates you from that experience as well.

[rffffffff]

Originally Posted by john61ct

90% of rated capacity, if measured at 0.1C or lower

is a **terrible** result, marker of shoddy maker for sure.

On the big very reputable makers' cells, 4-8% above rated is the norm.

One batch of 180Ah Winstons I got measured at ~12% over, but that was back about 15 years ago

On the video will prowse did he got 282ah from 280 rated batteries at 1C, pulling 292amps at the end. It was pretty impressive honestly.

https://youtu.be/3U4ZfQ_IToI

One battery was a little funky but the whole pack of four performed well together.

[john61ct]

Just as important as cell quality itself

is very close matching so all the cells are very close to identical.

That's why getting fresh production Grade A direct from the factory or from a known-good reputable vendor, supply chain is **so** important.

The cheap stuff sold via Ali even if genuine from top reputation makers, is 99% mixed bag QA rejects, often secondhand sold as new etc.

The weakest link determines the capacity / reliability / longevity of the bank as a whole.

[rffffffff]

Originally Posted by john61ct

Just as important as cell quality itself

is very close matching so all the cells are very close to identical.

That's why getting fresh production Grade A direct from the factory or from a known-good reputable vendor, supply chain is **so** important.

The cheap stuff sold via Ali even if genuine from top reputation makers, is 99% mixed bag QA rejects, often secondhand sold as new etc.

The weakest link determines the capacity / reliability / longevity of the bank as a whole.

matching is important for sure, but they have figured out a way to 'top match' and 'bottom match' on the forums, and I will buy a couple of spare packs so I can ditch the two that are the most different.

I think you may be underestimating the communication and reliability of the supply chain that I have seen, with the manufacturers reps directly on the forums, and the group buy guy negotiating good prices with multiple vendors that don't want to lose his volume so they make sure he gets decent cells. People have looked at the reports and seen issues or cells that didn't look matched well and they have swapped them with closer numbered cells before shipping. They seem to actually care about customer service and reputation more than you would imagine.

[john61ct]

Yes and those (when genuine) are the way to go.

But go read the OP. . .

[rffffffff]

That's why I recommended the group buy on diysolarforum. They're still the same suppliers from alibaba, just a little extra security and accountability.

[s2mikon]

Originally Posted by kazetsukai

If they are lithium, they're compromised of several cells in series. If you intend to parallel them, don't. Parallel only at the cell level, otherwise energy moving between them will reduce cell life. Also, if a cell in one of the batteries fails, you could end up with a condition where the other batteries in the bank uncontrollably dump their energy into the battery with the bad cell, overcharging the good cells.

I ran Tesla packs in parallel (24V) for a while, moved to series (48V) for longevity, and to better leverage my MPPT charge controller.

First off sorry to hear you lost your job been there done that. So just for illustration if I use 4 280 AH cells in series I would have a 12 volt 280 AH battery pack right? If I use 8 280 AH cells with 4 pairs in parallel and connect those pairs in series I would have a 560 AH 12 volt battery pack right? Of course a 24 volt battery with all cells in series would be better.

[rffffffff]

That’s correct. With some of what I heard about paralleling these packs it may be worth switching to 24v if possible and using dc - dc buck converters for 12v things you don’t wanna buy again... but I’m not buying another $1200 inverter so I’m sticking to 24v instead of going all the way to 48 by using 16 in series personally.

[s2mikon]

Originally Posted by rffffffff

That's why I recommended the group buy on diysolarforum. They're still the same suppliers from alibaba, just a little extra security and accountability.

Good morning northern neighbor. Have you bought any of these yet? I have been looking at this too and don't want to be penny wise and pound foolish. I looked at the video link you posted, it looks impressive. Of course anytime you buy Chinese made you are taking a risk. I've won some and lost some on Chinese made items. I'm sure that even battle born are Chinese cells.

[rffffffff]

Originally Posted by s2mikon

Good morning northern neighbor. Have you bought any of these yet? I have been looking at this too and don't want to be penny wise and pound foolish. I looked at the video link you posted, it looks impressive. Of course anytime you buy Chinese made you are taking a risk. I've won some and lost some on Chinese made items. I'm sure that even battle born are Chinese cells.

I haven’t bought them yet, but if you want to feel better about it look at diysolarforum and see the experiences there. They’ve been on it since June it seems and I didn’t come across any negative experiences yet... I’m sure there are some and I may have missed it but even if you have to buy double the amount of cells to get it right it’s still cheaper than anything else out there. It’s hard to pass this one up.

[s2mikon]

As soon as I finish my morning chores I'll ask Dear Wife if I can look at another forum.

[Jaybz]

Originally Posted by PNW_Steve

I am going to be placing an order for various batteries, BMS and such. If anyone wants to join in, let me know.

I would be very interested in joining in.

[turf]

when i got my battery, the customer service from the seller was outstanding. i would not hesitate to purchase again from them.

i figured my charges and sent the money to china on an electronic transfer. i should have waited for the company to make a me a bill, because they discounted shipping from the original bill. i had overpaid about $100. they refunded the difference, but transfer fees ate a big part of it. it took a week, but i received the refund from my overpayment.

they also sent videos of my batteries, wrote my name on them, measured matching voltage on them. then i waited. the boat from china was 6 weeks. i got the batteries the day after fedex tracked the packages in the US.

the same batteries they wrote my name on.

another forum member was on the DIY Solar forums the same time i got my battery. i thought he did the same. some day _Dzl_ will probably chime in

anyway....

my regrets:
i should have gone bigger.
my build is sketchy - i see big premade packs on their website i'd choose over building another from scratch.
the change over from lead acid is'nt really plug and play

[john61ct]

Originally Posted by s2mikon

if I use 4 280 AH cells in series I would have a 12 volt 280 AH battery pack right? If I use 8 280 AH cells with 4 pairs in parallel and connect those pairs in series I would have a 560 AH 12 volt battery pack right? Of course a 24 volt battery with all cells in series would be better.

It is not possible to get to nominal 12V from li-ion cells at nominal 3.7V

5S plus a "12V DC-DC" converter or "voltage stabilizer" would work.

7S gets to 24V nominal natively though.

And yes just one string, the Ah of each cell at the capacity desired for the whole pack is best

unless you need redundancy for a mission critical use case, then use 2 strings.

3P would be as high as I'd go using an S-first layout..

[rffffffff]

Originally Posted by john61ct

It is not possible to get to nominal 12V from li-ion cells at nominal 3.7V

5S plus a "12V DC-DC" converter or "voltage stabilizer" would work.

7S gets to 24V nominal natively though.

And yes just one string, the Ah of each cell at the capacity desired for the whole pack is best

unless you need redundancy for a mission critical use case, then use 2 strings.

3P would be as high as I'd go using an S-first layout..

This is completely true for 3.7v cells but the ones we’re talking about are nominal 3.2, 3.65 high cutoff (14.6 for 4 cells) and 2.5v low cutoff (10v for 4) so they’re pretty great for 12, 24 or 48v systems.

You want to chop the top and bottom 10% off of the normal usage cycle so it’s a good range once you do that, albeit requiring custom charge profiles.

[john61ct]

Yes sorry I thought we were talking li-ion at 3.7

With LFP 4S makes perfect 12V nominal.

I use 3.45V charging for longevity, consider 3.0V a good LVC at high C-rates, say over 0.4C

For low current use cases, better to cut off a bit higher, say 3.05V or even 3.10V for good lifespan

[joeblack5]

I bought total 52 of the lishen 272 AH cells.. the lishen has a lower internal resistance , that is on paper. Also the test procedure seems to be slightly more robust then the eve cells.

A friend needed 16 cells for a 48 volt system for his home solar backup.
We want 8 cells at 12 volt for our small bus and 24 cells at 24 volt for Dory.
I bought 4 spares as to avoid high shipping cost for incase we had duds or dropouts.

They were stuck at FedEx for a long time.

For myself we are going to use the 8 cel bms.