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Wolf's PowIRwall
#11
A mentioned above here is the picture of the cell that had the rust hidden under the insulator.
I am now re-wrapping all my cells.




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#12
Update on 2 things.
# 1 I found another rusted cell that looked perfect on the outside had good readings as far as mAh, V and IR.

Sorry the picture is a little fuzzy but was trying to get as good as a closeup as I could.


#2 After watching HBpowerwalls youtube video https://www.youtube.com/watch?v=7rd4tDJ6eKs on rewrapping cells I gave it a shot.
Just a couple of changes.
I put the magnet on the cell first and slide it to the center then I put the cells on the back of a baking tin

 

Push the wrap down till it touches the tin then very carefully use the heat gun on low fan, high heat setting and point it straight down onto the top of the cell. slowly getting closer till the wrap closes over the insulator. You may still get an occasional insulator flyoff but much less than if you attack them from the side. Once the top of the cell is done you are in the clear.
The rest is easy and you will have perfect results every time. Takes the guesswork of the alignment of the wrap. Thanks for a brilliant method hbpowerwall!!


 10 more packs to go Big Grin

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#13
Those bastard insulators always time it just right, flying off as the wrapper starts to shrink!
Perhaps some sort of weight, or shrink wrapped magnet can hold it in place?
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Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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#14
Update:

So after Spot Welding the 5p Fuse sheets from Battery Hookup  (I really hope they get some more of theses sheets soon) I encountered a dilemma.
How was I going to get the power from the batteries to a connector safely and mechanically sound.
I couldn't just solder a big wire to the sheet somewhere and call it good.
Besides taking a mΩ reading of the sheet which is 12.5 inches  from end to end is ~ 5mΩ. enough to cause a small voltage drop.
So onto busbar design and planning

  

I spent a bunch of time looking at all kinds of busbar designs and sketched a bunch of them out and finally decided to go with my design #5.
The sides will be covered with Lexan to protect the cells and the wiring.


To bring it to reality I spun up some  AWG #8 solid copper wire with a drill to straighten it did some bending attached a 1/16 X 1/2 copper bus bar with solder and this is what the prototype looks like. It will be soldered to the fuse sheet every 3 or 4 inches. From the busbar I will use a marine tinned copper wire lugs AWG #6 1/4 Ring complimented with marine AWG #6 tinned cable, terminated with  Anderson PP75 Connectors.



Now to build a jig so I can mass produce 29 more of them for now.

Wolf
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#15
(03-30-2020, 12:50 PM)ajw22 Wrote: Those bastard insulators always time it just right, flying off as the wrapper starts to shrink!
Perhaps some sort of weight, or shrink wrapped magnet can hold it in place?
Yes sir - you've got to blow upwards 'just right' till the edge traps the insulator - burning your fingers sometimes Smile
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#16
I have found with the magnets and the baking pan trick if you hold the heat gun straight above the cell at about 6 inches with high heat (setting 4 on the Wagner Furno 500) and low fan (default setting) you can eliminate the insulator fly off almost to 100%. Patience is the key and slow movement of the heat gun. Additional benefit fingers and hands need not be used and no burns Smile


Again once the top closes you are in the clear.
This batch was done without a single fly off Big Grin

 

Wolf
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#17
Update

So how to replicate the prototype bus bars with a jig.

Ah Nice piece of wood cut 4 slots into it with a skill saw, 2 passes of the blade worked perfectly for a AWG 8 wire. Depth adjusted to the bend so the buss bars can all be at the same depth.
 

Then turn it upside down and place the copper plate under it with a concrete backer and solder. I used a Weller 100 Watt iron that worked perfectly.


OK so the jig is set up now  and works great! Now how to repeat this process and duplicate the bus bars bends the same every time.
Spin up the copper wire with a drill to straighten it, cut 14" lengths and bend the end with a pair of lineman's pliers.

End result

A little tweaking on some but that can be done on the second bend

Now how to reliably replicate the 2nd bend. Crescent wrench in a vice and a pair of slip joint pliers.

End result
 

After soldering the 4 bus bars to the copper plate The hole can be drilled while still in the jig to avoid  any bending of the bars.

Nice consistent results.
Now on to soldering the bars to the batteries. Since I was using the cell level fuse sheets by battery hookup that was pretty easy.
Still using the Weller 100W iron it took mere seconds  for each solder joint to attach to the sheet.


For the finished product.


Now only 11 more to go unfortunately I ran out of #8 wire but I should have some more today.

Wolf
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#18
(04-06-2020, 01:37 PM)Wolf Wrote: Update

So how to replicate the prototype bus bars with a jig.

Ah Nice piece of wood cut 4 slots into it with a skill saw, 2 passes of the blade worked perfectly for a AWG 8 wire. Depth adjusted to the bend so the buss bars can all be at the same depth.
 

Then turn it upside down and place the copper plate under it with a concrete backer and solder. I used a Weller 100 Watt iron that worked perfectly.


OK so the jig is set up now  and works great! Now how to repeat this process and duplicate the bus bars bends the same every time.
Spin up the copper wire with a drill to straighten it, cut 14" lengths and bend the end with a pair of lineman's pliers.

End result

A little tweaking on some but that can be done on the second bend

Now how to reliably replicate the 2nd bend. Crescent wrench in a vice and a pair of slip joint pliers.

End result
 

After soldering the 4 bus bars to the copper plate The hole can be drilled while still in the jig to avoid  any bending of the bars.

Nice consistent results.
Now on to soldering the bars to the batteries. Since I was using the cell level fuse sheets by battery hookup that was pretty easy.
Still using the Weller 100W iron it took mere seconds  for each solder joint to attach to the sheet.


For the finished product.


Now only 11 more to go unfortunately I ran out of #8 wire but I should have some more today.

Wolf

This looks really nice, good job. What happens if a cell goes bad? I don't really see an easy way to replace/remove it.

Thanks for posting all the pictures and letting us follow your progress.
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#19
(04-07-2020, 07:18 PM)NotSoAlien Wrote: This looks really nice, good job. What happens if a cell goes bad? I don't really see an easy way to replace/remove it.

Thanks for posting all the pictures and letting us follow your progress.

Thanks.


If a cell goes bad.............

Yea I was thinking that too. But as I have checked these cells 3 times I do not foresee a problem in the near future.
All these cells have passed an extensive V and IR check at least 3 times if not more.
That being said I am also building a 15th pack in case I have a pack in trouble.
Now to replace a cell yea well you would have to pull one side of the 5p strip off and find the offending cell and replace it.
You would then have to solder a fuse to the bottom cell and replace the sheet on the top.
In my case I would disassemble the whole pack check all the cells and replace as necessary. That's why I decided to go with an 80p
as  my original 204p was going to be impossible to work with in this configuration. My ideal solution is to have a couple or three spares for easy replacement and giving me the time to rebuild the offending pack.
I'm kinda sticking my neck out as I am a huge proponent of IR and the importance of it indicating the health and longevity of a cell.
I look at all the packs that have been put together without any regard of the IR of the cells and they are still running so with me and my IR "phobia"
I expect to be in good shape.
Only time will tell.

Wolf
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#20
Production has begun on the packs.
All bus bars have been completed and 9 of these packs have been built.
Every one (720) have been rechecked for IR and V and re-wrapped.

I must say I do like the Kweld a lot once you get it dialed in it gives consistent results.
Only 5 more to go and 1 spare.
Testing the Ah of the packs right now and will post results as soon as all of them have been tested.
Testing paramiters are:
Using Icharger x6 initial testing was done with a external resistor to allow 20A discharge. Once 3 packs where initially tested
those were hooked up in series to provide a charging and regenerative discharge holding tank capable of 30A either in or out.
Sneak peek at the results so far? OK



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