Get a load of these "Grade A" cells..

Will Prowse

Admin
Staff member
Moderator

Not surprising anymore. Did not pull full capacity. Even after I top balanced the pack.

Also, I am being told by some that these cells naturally bulge because the cell walls are thinner (because they are designed for use in EV's).

But some people are finding non bloated 302Ah cells. What is your experience? Are your large cells always bloated?
 

podilamaya

Solar Enthusiast
I got 32 calls from Michael which are supposed to be 310ah. (shipping and cells had a big drama, but that is totally different story). some of them were bloated and some were not, I tested few cells and they only reached the capacity of 290is ah.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Also, I am being told by some that these cells naturally bulge because the cell walls are thinner (because they are designed for use in EV's).
ROFLMAO and the Sun Rises in the West too. I suppose they rationalize that by saying "They make Pouch cells for EV's" too. Never seen any commercial EV's with Blue Cased ESS Grade LFP... Possibly some of the lesser makes in China like TukTuk's and LEV'
s like the PakYak (Imported into Nevada) https://electricimportmotors.com/collections/trucks

Tesla & Others may be also going to LFP BUT that's NOTHING like these Blue Skins.

EDIT, Just watched your Video.
In your last vid or two back, you yourself noted the cells expanding & contracting with charge & discharge so there is that. A bit of Undulation in the soft cases is no surprise and somewhat expected but no more than 2mm total is allowable I think BUT that likely varies a bit between brand/case types (Sino or Winston ABS casing type versus aluminium).
 
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Substrate

Solar Addict
LiPO pouches (whether they contain LFP or non-LFP) inside prismatic batteries, or for that matter laptops and cellphones are NOT supposed to swell. Imagine Apple, Microsoft, or any other computer manufacturer telling users that rocking laptops and cracked keyboards are ok.

Part of the problem can be due to cost-cutting in the manufacturing process, which takes a lot of time to do right. There is also the possibility that Grade-A turns into Grade-B during shipping and storage under high-heat conditions inside a ship-hold, or warehouse in Arizona in the summer.

This document from Schmuel De-Leon describes the process, and the problems of cutting corners. Although the voltages listed are wrong for our chemistry, the manufacturing process as described and problems involved are the same:


Again - ask any laptop manufacturer if they think the lipo pouches used in their laptops are "OK" to swell - with the reminder that "lipo" is a manufacturing process, albeit it gets confused with the higher-voltage non-lfp chemistries as a battery voltage spec, when it just means a way of making a cell with either LFP or non-lfp.

As noted in the document, the switch from gel polymer electrolyte to liquid electrolyte in order to achieve higher initial capacity is a concern - however I don't have any references that this technique is definitively being used in LFP Lipo's.
 
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Bob B

Photon Sorcerer
I think that what this guy is saying is probably true.

 

cinergi

1.21 Jigawatts
I have direct experience with EVE and Lishen cells - same physical sizes. The EVE's expand/contract and bulge a little depending on SoC. The Lishen's do not. It's obvious when handling the Lishen that the outer case is much sturdier. There's also no electrolyte sloshing around in the Lishen's like you hear in the EVE's. These two cells are obviously manufactured differently. So painting all of these prismatic cells with a broad stroke regarding expansion or bulging is over-generalizing.
 
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