DOUBLEPOW...Any experience buying these batteries???

R

ronwalling

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View attachment 9
Good Day SecondLifers,

Does anyone have experience buying from this supplier / manufacture in China.

https://www.alibaba.com/product-det...l?spm=a2700.7724838.2017115.76.83773e0fzQaWsW

I am seriously thinking of buying a couple thousand due to the low price.
I will of course buy a sample pack to ensure they are legit, however if anyone else out there has experience I would value your opinion.
(the advertsaysUSD$0.1 - 1.90per cell, however this is
image_fcilxd.jpg
not the case I was quoted USD$1.37 for10, USD$1.33 for 100, 1.30 for USD$1.30 for 1,600+ and USD$0.95for 10,000. I didn't ask about more.Shipping,customs clearance and GSTnot included.)

The "salesman" stated they manufacture all their own cells and guarantee these cells are 2600mah +/- 10%. The advert stated "protected" however they dont state the full specifications, i.e current draw, max current. I could have missed it on the website, and I am waiting for a response to my request.

Perhaps I am getting ahead of myself.If I can get enough people together, perhaps we can get the cells more cheaply. (we would likely need to ship to a major port / customs clearing house... I.E sydney, brisbane, melbourne, Adelaide, Perth, etc). Not sure of logistics.

Any thoughts are welcome.

image_lppvfk.jpg

Thanks
Ron

PS: I have contacted the company and they have sent me this Specification sheet. Not sure if the constant discharge current is accurate because there is mention of 7800mah as well. Not sure if they are just making the numbers up or if they are actual? Comments appreciated.
 

Attachments

  • Doublepow 18650-2600mah-3.7V spec.pdf
    299.5 KB · Views: 319
Hi Ron, knowing Chinese suppliers you will receive sample parcel in excellent condition ,for your big order I wish you a good luck
 
Moved thread to appropriate location. This is a "question" about buying cells. Please only post in the Marketplace if you are Buying/Selling to other members.
 
Korishan said:
Moved thread to appropriate location. This is a "question" about buying cells. Please only post in the Marketplace if you are Buying/Selling to other members.
Click to expand...

Sorry about that. I am new here. Thanks for moving appropriately.
 
Best option - ask them for test data for the cells and cycle life. If they are making them and are anything reasonable they will have actual test data for many cycles and not just a line chart or image copied from another site. A lot of sellers are re-wrapping cells with issues as their own brand - rejected low capacity cells from other production lines.
 
What is the C rating of these cells? I didn't see a rating at first glance...
 
completelycharged said:
Best option - ask them for test data for the cells and cycle life. If they are making them and are anything reasonable they will have actual test data for many cycles and not just a line chart or image copied from another site. A lot of sellers are re-wrapping cells with issues as their own brand - rejected low capacity cells from other production lines.
Click to expand...
 

Attachments

  • Doublepow 18650-2600mah-3.7V spec.pdf
    299.5 KB · Views: 328
Min capacity 520mAh? Not sure if I was reading that correctly.

Weight doesn't match between ad and spec.
 
I have a hard time trusting these sellers - never really got much from Ali Stores - what sort of buyer protection do they have?
 
Why would you even consider buying questionable cells? Because of the price? You get what you pay for! When buying new cells there are plenty of sources available selling high quality cells. Also, don't go 18650 when buying new cells. It's a huge effort and a waste of time.

I mean, come on. 2600mAh +/- 10%?! Really?! This is not acceptable at all. Also they aren't able to provide a proper datasheet as it seems. It's absolutely clear that you don't buy these cells. There is not a single reason why you would do that.
 
ronwallingford@gmail.com said:
completelycharged said:
Best option - ask them for test data for the cells and cycle life. If they are making them and are anything reasonable they will have actual test data for many cycles and not just a line chart or image copied from another site. A lot of sellers are re-wrapping cells with issues as their own brand - rejected low capacity cells from other production lines.
Click to expand...
Click to expand...

Typical data sheet from a cell supplier - ask for actual cycle test chart/data as this is what any reasonable manufacturer would invest in if they are making and selling anything worth buying. The data if it looks like a curve/line on a chart, it is a line and not an actual test... real test data over a period of time usually contains a small bit of measurement noise due to the inability to test in complete isolation for 500+ cycles.
 
Can you post an example completelychard? I haven't seen one yet. (kinda new to 18650's)
 
Bubba said:
Can you post an example completelychard? I haven't seen one yet. (kinda new to 18650's)
Click to expand...

Look at the Cell Database and just pick one. Then look at the datasheet for that cell. That's what datasheets should look like.
 
The cycle life tests can look like this (Battery Universe website) with relatively few sample points and incomplete testing... looks like a nice reasonably linear line...

image_jxhogi.jpg


Or with longer durations and less controll of the tests like this (temperature variations usually cause part of the noise) - also imcomplete testing....

image_socgqx.jpg


Or more like this were the actual end decline of the capacity accelerates to failure, in this case lead-acid.

image_eweeiv.jpg


Lithium cells that suffer from any expansion distortion in the charge/discharge cycle (all 18650) will suffer a failure that is not completely linear and will accelerate towards the end.

Linear interpolation (wishing the cells would last that long..) can make it look like the cells will last longer than you will... especially if the charge/discharge process does not fully take into account the increasing rate of self discharge.

image_vgdxhr.jpg


Again, chart from battery university...

This is the sort of end of profile of failure that is nearly always chopped out / excluded from any cycle data test that is made public...


image_gfxrif.jpg
 
I ordered a few cells to test from this company and they tested slightly above rated capacity. I then ordered 56 2600mah 5C cells for $1.85/ea (same that I tested) for a pack and it now has been cycled approx. 100 times and its still going strong. I will absolutely be ordering more from this company.
 
ronwalling said:
View attachment 9
Good Day SecondLifers,

Does anyone have experience buying from this supplier / manufacture in China.

https://www.alibaba.com/product-det...l?spm=a2700.7724838.2017115.76.83773e0fzQaWsW

I am seriously thinking of buying a couple thousand due to the low price.
I will of course buy a sample pack to ensure they are legit, however if anyone else out there has experience I would value your opinion.
(the advertsaysUSD$0.1 - 1.90per cell, however this is
View attachment 5619
not the case I was quoted USD$1.37 for10, USD$1.33 for 100, 1.30 for USD$1.30 for 1,600+ and USD$0.95for 10,000. I didn't ask about more.Shipping,customs clearance and GSTnot included.)

The "salesman" stated they manufacture all their own cells and guarantee these cells are 2600mah +/- 10%. The advert stated "protected" however they dont state the full specifications, i.e current draw, max current. I could have missed it on the website, and I am waiting for a response to my request.

Perhaps I am getting ahead of myself.If I can get enough people together, perhaps we can get the cells more cheaply. (we would likely need to ship to a major port / customs clearing house... I.E sydney, brisbane, melbourne, Adelaide, Perth, etc). Not sure of logistics.

Any thoughts are welcome.

View attachment 10844

Thanks
Ron

PS: I have contacted the company and they have sent me this Specification sheet. Not sure if the constant discharge current is accurate because there is mention of 7800mah as well. Not sure if they are just making the numbers up or if they are actual? Comments appreciated.
Click to expand...
I think they mean 2520 minimum capacity, not 520, lol. 3C discharge would imply that they are relatively recent good cells, not rebranded old junk. Price range is normal for this type of cells. I had similar 2600mAh grey for testing, they were up to declared specs.
 
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