How to buy cells

[kenryan]

I have never bought anything off of Ebay or alibaba.

I want to build a 24v LiFePO4 battery of approximately 5,000 to 7,500 watt hours.

What is the best way of negotiating the maze of cells offered so that I make a smart purchase?

This battery will perform two functions: power for an RV and backup power for a house.

Thanks for any help you can provide.

 

[snoobler]

Welcome to the forum.

Two trusted sources are:

Introducing the New & Improved Shenzhen Luyuan Technology Co.

Dear Members of DIYSolarForum, With the experience I gained while working with Shenzhen Xuba Electronic Co., which I am infintely grateful for. I was introduced to a group of very enthusuiastic and most helpul people which helped me to grow & improve my own knowledge which helps me to better...

diysolarforum.com

and

@Michael B Caro

There are likely more, but these two have a good reputation.

 

[Q-Dog]

I just bought a battery from here https://www.treelinepowersystems.com/24V-LiFePO4-Batteries_c_26.html and everything seems to be good so far. just under 2 weeks from order to delivery. Within an hour of delivery I had it together and taking a charge. I am going to paralell it to what I already have and need to build some cables and move a few things before I can put it to use, but the cells seem to be matched, and I didn't have to wait 3 months for it.

My only issue is the cells are stuck together with double sided tape and the terminal layout is opposite of how I wanted to do them. So, I'll either have to cut one cell apart from the new pack and move it around, or take my other pack apart and flip-flop the layout.

 

[Just John]

I have never bought anything off of Ebay or alibaba.

I want to build a 24v LiFePO4 battery of approximately 5,000 to 7,500 watt hours.

What is the best way of negotiating the maze of cells offered so that I make a smart purchase?

This battery will perform two functions: power for an RV and backup power for a house.

Thanks for any help you can provide.

Snoobler gave two excellent sources.
Always use a credit card.

 

[kenryan]

Does @Michael B Caro have a website?

 

[snoobler]

Does @Michael B Caro have a website?

No. He's a trusted forum user that "brokers" purchases with various other suppliers. Send him a message.

This is a VERY long thread started when he first began to offer services:

Lishen 270ah-272ah cell group buy.

Ok, this will be a longish post but I want to lay some foundation before taking orders on these cells. Eve 280ah cells appear to only be available at this point from suppliers that want a premium price for them From everything I can find, Lishen is extremely popular in China but has yet to get...

diysolarforum.com

 

[OffGridInTheCity]

One of my favorite US sources is Battery Hookup - I've purchased over 5,000 18650 cells over the last 3 years and all have been exactly as advertised. They don't do huge variety of LifePo4 and you don't say how big/many you are after - but Battery Hookup has this listing - https://batteryhookup.com/products/new-3-2v-25ah-lifepo4-topband-navitas-prismatic

 

[snoobler]

One of my favorite US sources is Battery Hookup - I've purchased over 5,000 18650 cells over the last 3 years and all have been exactly as advertised. They don't do huge variety of LifePo4 and you don't say how big/many you are after - but Battery Hookup has this listing - https://batteryhookup.com/products/new-3-2v-25ah-lifepo4-topband-navitas-prismatic

Not poo-pooing that source, but it's always worth considering a couple things:

1) $/kWh - A pack of 24 of those cells is $168/kWh vs. about $110-120/kWh for the larger commodity cells.
2) more cells = more labor and more cost in connections. Strapping together 4X 280ah cells is relatively simple and quick vs. building an 11P4S pack from 44 of those cells.

BUT they have a good reputation for cell quality (not so great reputation for packing of these particular cells), and they do seem to legitimately test if they say they do.

 

[kenryan]

I am having trouble finding any sort of specs on raw cells. For example, the Shenzen link above doesn't seem to provide any information regarding the cells other than voltage and amp-hour rating. In order to properly implement the battery once it is built, wouldn't I need to know the C rating for charge and discharge? Also, wouldn't I need that information to properly select a BMS?

 

[Just John]

I am having trouble finding any sort of specs on raw cells. For example, the Shenzen link above doesn't seem to provide any information regarding the cells other than voltage and amp-hour rating. In order to properly implement the battery once it is built, wouldn't I need to know the C rating for charge and discharge? Also, wouldn't I need that information to properly select a BMS?

The resources section of the board has many (but not all) of the spec sheets. I know it has spec sheets for the 280AH Eve cells, likely for the Lishen 272AH cells as well. It won't hurt to search and see. Most of the larger cells are rated up to 1C, although with commodity cells, better to stick to 0.5C (also documented in the spec sheet).

There are lots of things in the resources section, apparently many don't think to search, but it can be quite fruitful to do so.

 

[kenryan]

Thanks @Just John Is "Eve" a manufacturer, a brand name, or a battery type? Same question for Lishen. How does one know if they are purchasing "commodity cells?"

 

[Just John]

Thanks @Just John Is "Eve" a manufacturer, a brand name, or a battery type? Same question for Lishen. How does one know if they are purchasing "commodity cells?"

Eve and Lishen are cell manufacturers.
Commodity cells are cells that (for one reason or another) aren't rated grade A. Every single seller will tell you their cells are grade A.
Unless they come with a manufacturers test report, they are not.

This post is an example of grade A cells:

Introducing the New & Improved Shenzhen Luyuan Technology Co.

My sixteen 280 AH cells are being shipped now. These are the specs. Now I need to make sense of them!!

diysolarforum.com

To the best of my knowledge, VERY FEW actually offer grade A cells, but every single vendor claims to.
The commodity cells are generally a much better value, you get a lot more storage for the same price. Grade A cells start at $120/cell plus shipping. Commodity cells are much cheaper. You may or may not get the rated capacity for the cells, but 270AH storage for $85/cell plus shipping is a much better value than the grade A if you want a lot of storage. Many will give you full rated storage or above, might just have been sitting on the shelf too long (as an example). Mostly they are mis-matched in the IR or capacity, this will give you "runner" cells at the extreme end of charge or discharge, so just avoid the extreme ends.

Commodity cells generally do better when not used at 1C rates, which would be the vast majority of users here. I have no complaints about the value of the commodity 280AH cells I purchased.

 

[kenryan]

Thanks @Just John

Very helpful.

 

[kenryan]

What are the relative advantages/disadvantages of ordering through Shenzhen vs @Michael B Caro ?

 

[Just John]

What are the relative advantages/disadvantages of ordering through Shenzhen vs @Michael B Caro ?

Amy will always have the grade A in stock. Eve manufactures them when you order. For commodity cells Michael is more likely to be able to obtain them and have a better price since he uses multiple companies.

To me, the most important factor is do the cells arrive undamaged. Amy packs extremely well. Michael uses multiple companies, so it is likely harder to say. I however have no experience with Michael other than by reputation, and it's good.

I would rather receive undamaged cells the first time, and would gladly pay a couple of dollars extra. Others are much more interested in the cheapest price. It is up to you to decide. You can likely beat their prices on commodity cells, but not by a lot. Both will get you cells with as close to zero risk as is possible when ordering things shipped from China.

 

[Just John]

I have never bought anything off of Ebay or alibaba.

I want to build a 24v LiFePO4 battery of approximately 5,000 to 7,500 watt hours.

What is the best way of negotiating the maze of cells offered so that I make a smart purchase?

This battery will perform two functions: power for an RV and backup power for a house.

Thanks for any help you can provide.

FYI, sounds like you want a 24v battery. If you order commodity cells, order 9 just in case. Probably not a necessity, but I wish I had ordered extra when I bought commodity cells. If you order grade A, don't bother.

 

[Michael B Caro]

Michael is more likely to be able to obtain them and have a better price since he uses multiple companies.

I also have true grade A cells that come straight from the manufacturers....not just commodity cells.
And I have them at a much better price than Eve cells.

 

[snoobler]

FYI, sounds like you want a 24v battery. If you order commodity cells, order 9 just in case. Probably not a necessity, but I wish I had ordered extra when I bought commodity cells. If you order grade A, don't bother.

I did this with the Eve commodity cells. Oddly enough one of the 9 was a notable outlier, though still a good cell.

 

[Just John]

I also have true grade A cells that come straight from the manufacturers....not just commodity cells.
And I have them at a much better price than Eve cells.

Do they come with the test reports? Because literally, they day after I ordered, they were manufactured and the test reports sent.
Grade A from Eve means it can't be more than 5 months old (that's why there were a lot of commodity cells).
I'd be very interested in grade A Lishen.

 

[Just John]

I did this with the Eve commodity cells. Oddly enough one of the 9 was a notable outlier, though still a good cell.

Yes, that's why I mentioned it. Of the 16 I ordered, 14 measured 274 to 281 AH, two measured around 268 AH. A pack is only as good as the weakest cell. I caught the tail end of the Eve cells last year. Still a bargain.