My guess is cost and ease of connecting them to the tabs of the pouches inside. Years ago my Prismatic Winston and Thundersky cells actually had one terminal that was copper and the other was aluminum.I dont understand why the manufacturers dont make the terminals from copper anyways
Wonder where they get those holders from....makes a neat job of stringing 8 cells together.here they say 4.5nm
I think those may be proprietary to their system. I did not see any significant compression like has been discussed here.Wonder where they get those holders from....makes a neat job of stringing 8 cells together.
Yeah, but the compression came later with the metal plates(at 2.05) on the outside to stop " irreversible swelling".I think those may be proprietary to their system. I did not see any significant compression like has been discussed here.
Cost and weight. Aluminum is 1/3rd to 1/4th the cost of copper, and 30% of the weight. But mostly cost. Those Yuans add up.My guess is cost and ease of connecting them to the tabs of the pouches inside.
Yes, this has been thoroughly discussed as anti torsion in the past 100 or so posts of this very long thread. For the LF280 cells which are the subject of this thread the anti torsion of the terminal is LESS than 8Nm. Most people have concluded that 4 to 5 Nm is sufficient for the torque of the terminal bolts.Normally, the manufacturer will list the suggested torsion on their specification. If not, just ask them.
I would disagree. The clearance between the roll (or accordion stack) and the case is negligible. If you try to compress the center of a cell, it doesn't move appreciably, even with 20lbs of force. This tells me that the electrode/separator roll is tightly packed inside the casing. Also the fact that the spec lists 0.5mm of expansion during charging shows there is little or no free space inside. This makes sense of course, as movement between the two is likely to cause damage long term. The layers are as thin as possible to maximize energy and material density. The case itself is quite thin, and even the short sides would buckle if they were carrying significant load. Thus the majority of the clamping load is carried by the roll itself. Obviously the roll isn't crammed into the corners though. If memory serves, when they manufacture the cell, a tool expands the cell casing slightly, then the roll is inserted. A series of dies compress the casing and roll until its square ensuring a tight fit. Then the electrolyte is added, and the cell is capped.
The attached excerpt briefly discusses how pressure is needed in wound cell designs.
X ray photo of an jelly roll from a lithium cobalt cell.
View attachment 22187
Hello
can I also install the EVE 280AH LIFEPO4 cells horizontally without problems?
thanks
do you mean this?Wonder where they get those holders from....makes a neat job of stringing 8 cells together.
4.5nm it is then... well spotted.
Thanks for the link, but i now wonder where the compression of the cells comes from with this set up?do you mean this?
My personal theory is that these large cells are primarily aimed at bus use. Thus the objective of the fixture mentioned in the data sheet is to prevent terminal movement and the accompanying loss of connection and power. I also suspect the torsion measurement of the terminals means how much the terminals are rated to withstand before damaging the cell internally. I certainly could be wrong, but so far it seems like a fixture won't prevent a cell from bloating, and the torsion measurement certainly isn't the correct torque spec for terminal connection.Thanks for the link, but i now wonder where the compression of the cells comes from with this set up?
Yeah, all my terminal connections are only torqued to 4nm. Using flexible busbars, should keep all the stresses/vibrations off the terminal posts.My personal theory is that these large cells are primarily aimed at bus use. Thus the objective of the fixture mentioned in the data sheet is to prevent terminal movement and the accompanying loss of connection and power. I also suspect the torsion measurement of the terminals means how much the terminals are rated to withstand before damaging the cell internally. I certainly could be wrong, but so far it seems like a fixture won't prevent a cell from bloating, and the torsion measurement certainly isn't the correct torque spec for terminal connection.
I've now started assembling an EVE 280ah 8s battery inside one of my custom battery boxes from Amy.
Xuba Pre-built 200AH LIFEPO4 Battery??
Does anyone have experience with this plug-n-play pre-built XUBA 200AH LIFEPO4 battery? https://www.alibaba.com/product-detail/Xuba-4S2P-12V-200AH-Lifepo4-Lithium_1600137902571.html?spm=a2700.icbuShop.84.14.39f3b917IufXCf I've contacted Amy about them and she said they're build with grade A...diysolarforum.com
I chose custom larger dimensions because of my enormous 200A BMS, and because I wanted to mount a bluesea fuse on the positive terminal.
200A Smart BMS from LLT Power
Hi! Anyone used this BMS from LLT Power: https://www.lithiumbatterypcb.com/product/7s-to-20s-200a-smart-bluetooth-bms/ Model No: JBD-AP20S002 Looks like a good bargain, what your views?diysolarforum.com
I still need to crimp connectors to the Anderson cables and wire the case voltmeter to the terminals. Probably a separate common battery positive and negative busbar would be the cleanest.
View attachment 29607
I also haven't bound the cells or BMS yet. The MDF boards are 10mm each and were originally used to compress the cells between hose clamps outside the metal box. As it turns out 10mm MDF is too flexible for the task.
Happy Australia Day (here) . I have to buy a couple of extra cells from XUBA and was going to get them to build a custom box for me - I was going to spec it 1/4" or so larger on the interior (my BMS will be external). Anything you would have done different when speccing the box that I could learn from? All I really need is the box and none of the other stuff they show on their site for anderson connector etc.
My cell spec sheet said nothing about compression (120Ah Higee).Regarding extra space, you can either use the walls of the box for compression (Not advisable for Lishen cells), or have space for external compression (straps, plates, planks), space for the BMS and overhead room for the cabling and a battery fuse.