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To Space or Not To Space EVE 105 Fixture/Compression

lakespyder

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Joined
May 2, 2022
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After a major fail due to purchasing a GTK pack on Ali Express for my golf cart (You can see my struggles with that pack in another post of mine), I have now purchased EVE 105 cells and a BMS to build my first 16S 48v battery for my golf cart.

I just finished top balancing the new cells and am putting them together. This is my first build and I want to be sure to do it right. My question is should the cells be tightly bound together or should I use some spacing material to allow for expansion. I have the material and a plan on how to do it, but I was hoping to learn if there is any reason that I should not. It will be a minimal space, but enough to allow for a very slight amount of expansion, and my thought is that doing this would prevent there ever being any stress on the busbars. Additionally, since this is for a golf cart, the battery will not be stationary so possibly this could reduce overall stress some. I have found posts on larger cells, but not seen any in this forum on the EVE 105.

Are there any advantages or disadvantages of putting this rubber material between my cells to provide space?

Thanks in advance



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I have read 2 different manufacturer documents, but have not seen anything that would indicate if this is a good or bad idea. It does show that they tested using a 300kgf clamp force. Does this imply that it would be better to have them firmly bound together, rather than using any type of spacer?



Screenshot 2022-06-07 143842.jpg
 
My question is should the cells be tightly bound together or should I use some spacing material to allow for expansion.
Nothing in any manufacturers literature suggests that room for expansion needs to be provided. They all talk about fixture or apparatus to provide compression. My guess that is to prevent expansion. That is how I have compressed mine.
 
Nothing in any manufacturers literature suggests that room for expansion needs to be provided. They all talk about fixture or apparatus to provide compression. My guess that is to prevent expansion. That is how I have compressed mine.
Thanks for the info! I decided not to put the spacers between each cell and used poly masking tape to hold each pack of 8 together. I do plan to put the spacers between the two packs before using fiber tape to hold them together as one. In that way I can slip the NTC wire in between the 2 packs. Is in between the 2 banks the correct installation for the NTC wire?


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How is your build going Lakespider?
I have just ordered 16 x 105ah EVE cells from Docan and starting to plan how to box them up etc. Any photos of your build?
Thanks
 
I think of the plastic sheets as isolation sheets more than spacers. I don’t trust the blue shrink wrap to isolate the cases from each other.
 
Ya'll quite anal. Time will kill the battery not because you didn't compress.
 
How is your build going Lakespider?
I have just ordered 16 x 105ah EVE cells from Docan and starting to plan how to box them up etc. Any photos of your build?
Thanks
Hi Jeff,
The build went well and has been use all summer. I used cutting boards, and grooved them with my table saw, then used a combination of JB Plastic Weld & a plastic stapler to hold it together. I also used plastic sheets to create an internal box, so the cutting board box is just added stability & protection. This probably isn't the ideal boxing, and certainly not the easiest, but it worked for my one time build to custom fit into my space. Here are some pics of my build..... As for spacers, I only used a couple of small plastic strips between the 2 banks so that there would be room for me to insert the temp sensor.
 

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Nothing in any manufacturers literature suggests that room for expansion needs to be provided. They all talk about fixture or apparatus to provide compression. My guess that is to prevent expansion. That is how I have compressed mine.
Will has 2 videos showing the inside of the server rack Lifepower4 batteries cells.. they appear to me having black plastic spacers between the cells to allow for expansion.. yes they are only 100ah cells but I’d assume expansion is fairly similar for most prismatic aluminum cases cells.. so therefor the same compression tactics could be implemented.. the server rack batteries I think are good for 6000 cycles (or 10,000?) and are barely compressed other than strapping. The server rack batteries have a limited amp output and maybe that’s why it’s fine to not thoroughly compress the cells used.. the cell tested in manufacturers literature was most likely put through hell using much higher c-rates than the cells in the server rack batteries are limited too via their bms.. with those much higher c-rates I’d agree it is absolutely best to compress as the literature explains. However I will be compressing mine for my home battery anyways..
 
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