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So It Begins
#31
I understand you want to hurry up and finish your monster power-wall.
But you can mix 123123,but why you don't do a capacity check.
If one or two cells are really low they will drag the whole string down and thus your pack in total capacity.
I would strongly advice to test the cells, what if there are 6 almost dead?
Would be a waste of work.
I would like to know why you dont want to test them, it takes a couple of days.

With best regards Igor

Looking great by the way, my compliments
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#32
If you don’t capacity check your heading for trouble. I have obtained leaf modules anywhere from 250wh to 360wh - that’s a big difference and unless you sort your stacks roughly equal some will be way better than others and will never balance.
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#33
Patience Grasshoppers , I'm working on it, my little charger only goes so fast. I will have some numbers for u before long. No battery is discharging on it own , was checking voltage at cells every other day before I starting stacking them.
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#34
If you need spacers, see: https://powerwall.fergo.net/2020/03/13/the-spacers/

Any laser cutter will be able to take the PDF and laser cut the spacers for you. Thou, don’t make the same mistake I did and use 3mm aluminum- it’s a tiny bit thinner than 3mm steel and it adds up when stacking 20 modules. :-)

Also note: you should be balance charging!!
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#35
With all due respect: checking v alone does not give you soh only soc.
The soh is pretty important.
Here is how it should be done in my opinion:
Each separate cell must be charged to full (8.3v), then discharge to there minimum voltage (5v) with a discharger that counts watts or ah.
Optimum is 41ah ofcourse--->100% SOH.
Very good would be a minimum of 32,8ah left------>80% SOH
Duable:60-80% soh--->24,6ah- 32,8ah

Those numbers you write down on each cell (including date of testing), also handy for future testing (after 3 years or so) to see how your wall is holding up.
Before stacking/connecting your cells you can calculate for each string how much it holds total, so you can build all the strings in the same capacity.
I would be really a waste of time if there would be one cell with just 20% (8ah) of capacity left, that cell will break your whole powerwall.
Make 7 packs that are close to each other and start building from here, with the lowest SOH on top.

This is my favorite tester:
https://nl.aliexpress.com/item/400105712...web201603_
Oke it can do max 3A an hour discharge, but it will give you the numbers you need.
It will take a 10h to 15h to complete for each cell, just buy 10 or so,they dont cost much

To charge if needed:
https://nl.aliexpress.com/item/328726073...4c4druX18I

Before connecting them in series let them balance like slimf said, by just connecting each string parallel and let them equalize.
That will be a very good start, the Batrium can only do so much, but equalizing would give it a good start.
With this little extra effort you will get the MAX capacity and lifespan out of your powerwall.

This is just some advice, it is your wall.
Looking forward to see the rest of the build.
With best regards Igor
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#36
(10-09-2020, 11:37 AM)daromer Wrote: But Wolf dont forget all of us running without testing it and still no issues Wink  IR is alot more important on high current system or those with very few cells. And if you test at your max current (Like you do on 18650 or should do...) You also know that the IR is low enough.

I still dont test IR on any cell going into powerwall and will not do it. I push the cell into the Opus and let it do its job. for me the time processing the cells is so important that i just dont see the value in knowing the IR. I rather stick to one test only Wink

Yes IR is a valuable factor but its not needed to build a generic wall as such for it to work.  Imagine sorting my 29000 cells based on ir.. WOW.....

I know a lot of you are refusing to check IR and that is fine with me. Your choice!
The problem I have with your method is that time as you mention so eloquently is at a premium for you. I understand as it is the same for me it is precious as we can never get any of it back. So in defence of my procedure checking IR first is my time saver as it allows me to avoid testing the cell to begin with and not wasting the chargers time to find out a cell won't perform. I eliminate an 8 hr or so cycle on the OPUS or whatever charger/tester is used and free it up to actually test a cell that will give me good results. So does IR save time? In my case yes quite a lot. 29000 cells is a lot of cells and how many cells did you test to get those? Probably at least twice that if not three times. If testing the cells for IR first you could have eliminated a major portion of testing from the beginning.
So time saving by not checking IR is a misnomer.
How many times have you loaded up the OPUS chargers and pulled maybe 2 or 3 good cells out of 24. I think you have 6 OPUS chargers?
Be honest and tell me that never has happened to you.................
As far as I know the world is still relatively free and it is your choice to do as you wish as for me I recommend checking IR you don't, so we chose to agree to disagree.
Wolf
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#37
(10-09-2020, 11:25 AM)Wolf Wrote: Sheesh all this talk of SOH, SOC but not a word about IR.
I just scratch my head that this reading easily obtained with a very reasonably priced tester ≈$50US
can reveal so much about a batteries health and no one uses it. Huh
I don't get it ..............
It is the first measurement I do on any battery before I commit to doing anything with it.
It is also a measurement I use to balance the cells within a pack.
There are many threads out there that discuss the advantages of IR, matching cells, and how cells behave in parallel.
Just shaking my head why anyone would try to start a car without checking the tank for gas and the motor for oil and then wonder why it wont start or breaks down.

Wolf       Yea I agree with this, if IR is high the battery is going to self discharge and  a indicator of health. My charger shows IR as it is charging. These cells charge so easy compared to lead acid. 
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#38
(10-09-2020, 12:32 PM)Heilopilot Wrote: ...............charger shows IR as it is charging. These cells charge so easy compared to lead acid. 


Oh yes they do charge very nicely compared to Pb.
Glad you are at least looking at IR
Looking forward to your build.

Wolf
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Great ABB shunt breaker seller River City Industrial
Great prices and superb service.
 [Image: em2566%20(1)__19172.1521541365.jpg?c=2]

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#39
(09-27-2020, 07:10 PM)Heilopilot Wrote:
nice post
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#40
Came across this link can check a Nissan leaf battery in 3 minutes for capacity,  short read.
https://www.blue-scientific.com/grading-...batteries/
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