Creating a spare pack

Dr. Dickie

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Sep 23, 2020
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I have finally processed and cataloged my cells for my Powerwall build (14S160P). It was my understanding that many folks make an extra pack, so they have one to swap in if they need to fix something in one of the packs. Is this common or unusual?
 
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floydR

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Aug 23, 2017
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Not sure about common but makes good sense I will be making an extra pack, Just haven't decided if I go 80p or 160p. leaning towards 80p easier to manage. and making 14s80p2p
Later floyd
 

OffGridInTheCity

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Dec 15, 2018
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I started off thinking the same as you and made all my packs the same for swap out - but not sure how desirable that is in practice due to different cell chemistries. I have less problems if the entire 14s100p battery is the same cell type. So I've migrated in my thinking that spare cells (of same chemistry) sitting at 3.7v for long term storage are better than spare packs. This will let me rebuild/fix packs and since I have 6 separate 14s batteries I have enough capacity to take one offline to work on it without disabling the overall system.

I'm nearing 1,000 cycles and no problem so far... not sure if all this will be put to the test soon or many years yet, will definitely share when it happens :)
 
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jdeadman

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Mar 28, 2017
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I have 1 spare sitting at 3.8V that i can easily get charged or Discharged similar to the rest of a string to swap out for errors. I also like to have more strings (packs of 7 cells in series) and have the ability to take down a Pack without loosing power totally
 

Dr. Dickie

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Joined
Sep 23, 2020
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123
Thanks all!
Since I have all same cells (year, chemistry, everything). I will make up an extra pack. What complicates my situation is, my packs have a "handiness" to them. That is, every other pack had buss bar that exits the packs differently (one in the front the other in the back). But I will make and extra one, and just have to undo the welding if I want to swap it out. Unfortunately, I don't have enough cells of the capacity I want to make 16 packs.

On second thought, I think I will take the 10 cells and just discharge them to about 3.6 V for storage, and not put together the spare pack until needed. In fact, I can use my two MegaCell Charger to discharge the cells!! Perfect, I want to try it out and this will give me the opportunity to use it and get familiar.
 
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