Group 24 cells

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Re: Group 24 cells

Postby Burgerman » 18 Jun 2024, 16:15

If all are that close I woud just build. Be aware that just because they all read the same at this state of charge, that doesent mean they will be balanced fully when charged. But thats good enough to build the pack.
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Re: Group 24 cells

Postby jefferso » 18 Jun 2024, 18:09

I had a little bit of assistance today so just set them up to sit for a while before building.

The bus bars Docan Power sent are two pieces each banded together with black plastic, almost like electrical tape but with no edge. Maybe it's some kind of shrink plastic. Are they meant to be used like that for extra flex, or are they single items packed together in pairs? There were 4 banded pairs with each box of 4 cells.

Wire interconnects are from shirley_hkg

IMG_2517-parallel.JPG
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Re: Group 24 cells

Postby Burgerman » 18 Jun 2024, 18:43

They must flex as the chairs bounce them about and even heat and cold as well as charge/discharge changes cell dimensions. Solid ones put stress on terminals causing fatigue and failure. And this is why I never use those at all. I just make wire connections like the ones shirley supplied you. They are better. As long as tinned, and soldered and not bare copper.

Also once you get below around 4.55V on these types of cells, the voltage can be quite different from state of charge, and varies between cells by a few mV. But at this part of the discharge curve (below 3.4V) then even identical voltages can be a good couple of Ah out of balance.

So connecting together while topping off charge will 100% balance them, as you charge at 3.60V and they are all FULL at 3.50V as far as capacity goes, but just connecting together as you have at a lower state of charge will not balance them. Because the same voltage can apply across batteries of different state of charge. For e.g if one cell is 1 degree warmer, then its voltage wil be a few MV higher. If one cell has a tiny difference in internal chemistry (less dry condition during build, minute difference in impurities etc) then it may be a few mV higher or lower at the same state of charge.

This is why a typical BMS that balances all the time rather than only above 3.45V or 3.50V actually can unbalance a pack all day long in use. Causing many hours of rebalancing later on during charge.

This is why with this chemistry we only ever top balance.

But wht it will do is drag up any substantially low ones. Or drag down any that are substantially high. This means that it will be easier to top balance when charging later on. But in yor case with all identical voltages then enen if they are a little unbalanced by capacity, then no current is going to flow anyway and so they wont really change. But it wont hurt either.

You may still find you have some time on charge needing to balance though.
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Re: Group 24 cells

Postby jefferso » 18 Jun 2024, 21:26

Does this diagram make sense for connections?
Will be using Shirley's beefy interconnectors represented by the red arcs.

I'll add balance wires to the diagram once I've understood where they should go.

160Ah v4.png

IMG_2514-interconnectors.JPG
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Re: Group 24 cells

Postby Burgerman » 18 Jun 2024, 21:56

You wiring is correct.

Your cell numbering is reversed.

Cell 1 is the one that starts with the main negative (and the 1st of the 9 cell balance wires), and its + end is cell 1 one (the 2nd wire out of 9) the balance wires.

Cell 2 neg is the one it connects to. And that cell 2 + end is the next wire, the 3rd one out of your 9 balance wires. Rinse and repeat until you get to the plus + on the final cell 8 which is the 9th wire, a plus wire.

I have done this with hundreds of hobby packs and a few chairs, mowers, tools, etc and its all 2nd nature now!
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Re: Group 24 cells

Postby Burgerman » 18 Jun 2024, 22:23

So...

Like this.

Balance wire 0 goes to call 1 negative.
Every colour then goes to each cells positive in turn.

So after this every cell is numbered. Starting at 1.
Dark Blue = cell 1 (2nd wire on your balance connector)
Light Blue = cell 2 (3rd wire)
Green = cell 3 (4th wire)
Yellow = cell 4 (5th wire)
Orange = cell 5 (6th wire)
Pink = cell 6 (7th wire)
Purple = cell 7 (Which I have just noticed that I marked incorrectly as EIGHT!!!) banghead
Red = cell 8 (which is your final 9th wire.)
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Re: Group 24 cells

Postby jefferso » 18 Jun 2024, 22:48

That's great, thank you!

I was just working on similar. The only difference I think is I started numbering from 1 instead of 0.

160Ah v5.png
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Re: Group 24 cells

Postby jefferso » 18 Jun 2024, 23:40

Updated to number from 0 to 8 as per your previous and to match Shirley's balance wire labels.

160Ah for 2x group 24 v6.png


IMG_2532-shirley-balance-wires.JPG
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Re: Group 24 cells

Postby Burgerman » 19 Jun 2024, 05:06

In the lithium world, 0 is always the negative. So that 1 to 8 each represent a correct cell in turn. At least this is how the hobby world has done things for 20 years.

So better that way. Also better to make sure when you always connect the wire with say 4 on it to the terminal on cell 4. On the face of things you would think it makes no difference to connect to the other end of that connector (on the neg end of cell 5) instead if its easier. But it seems to sometimes change the graphs due to the resistance differences and possible disimilar metals (galvanic voltage difference). It shouldnt but it seems to be the case.
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Re: Group 24 cells

Postby jefferso » 19 Jun 2024, 13:58

I saw in some old threads mention of putting a bit of grease on the cell studs when tightening the nuts down. What kind of grease would be good for that? Is it just to help prevent corrosion?
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Re: Group 24 cells

Postby LROBBINS » 19 Jun 2024, 15:48

Stainless steel has a strong tendency to sieze, hence the need for something on the threads. Any grease should do in the chair environment, or even just some Loctite, but the strongest anti-sieze grease is copper (or silver) paste. If exposed to marine air, that might be a good idea, but in this case it's probably overkill.

Don't forget to put a fuse in your wiring! And, if you have the fuse in a SB50 removable link, it also gives you a convenient way to completely disconnect the chair (a very welcome suggestion from Burgerman). I've mounted Rachi's on the side panel of her chair with the fuse entirely within an SB50 with a length of shoelace attached to it and tied elsewhere a the other end. Thus, when traveling by airline, for example, I can pull that SB50 while being sure to not lose it.
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Re: Group 24 cells

Postby shirley_hkg » 19 Jun 2024, 16:08

His F5 has a breaker. No need to change.

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Re: Group 24 cells

Postby jefferso » 19 Jun 2024, 19:53

The Permobil F5 has 4 cables to attach to the 4 posts of the 2 12v batteries. One red, one black and two grey. The grey ones seem to go into the little white box at the back of the battery box. Does anyone know if the grey cable does anything other than connect the opposite terminals of the 2 12v batteries? Or is that where the breaker is connected?

Will I just connect the red cable to the positive of cell 8 and the black cable to the negative of cell 1 and ignore the grey cable?

f5-battery-cables.jpg
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Re: Group 24 cells

Postby Burgerman » 19 Jun 2024, 20:39

The grey cable is your breaker. Add this into the loop. At the positive end.
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Re: Group 24 cells

Postby jefferso » 19 Jun 2024, 20:45

Burgerman wrote:The grey cable is your breaker. Add this into the loop. At the positive end.


Thanks. So I'll connect the black cable to the negative of cell 1, the short grey cable to the red cable directly (not attached to any post, maybe with a nut and bolt, then perhaps covered in insulating tape), then the long grey cable to the positive of cell 8.
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Re: Group 24 cells

Postby jefferso » 19 Jun 2024, 21:53

I lost my ancient Windows 8 virtual machine from my old Mac laptop so I'm looking for the best Windows version to install on an older cpu to run the PL8 software. Is Windows 10 the best version for older hardware? I remember reading some posts about an LTSC version, is that worth getting? If I remember right, there's a version of Windows 10 that runs without requiring purchase of a licence.
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Re: Group 24 cells

Postby Burgerman » 20 Jun 2024, 01:11

Where to start...
Right now the ONLY good version of windows, is the 10, 64, IoT LTSC. That means, its Internet of Things. And Long Term Licencing version.

Why is that good?
Because windown is now full of crap, added nonsense that microsoft pushes on you as its their money maker. And it tries to force you to log in to microsoft, and to use their browser, and see thair ads, and so on.

Windows 11 is even worse.

There isnt a Windows 11 LTSC version yet, but there will be soon.

Meanwhile all other (noddy bedroom versions) of windows 10 is out of time (no longer updating, no more security updates as fixes and vulnerabilities are patched. And they are all full of crap and metro nonsense anyway.

So you need my copy of Windows 64 bit, LTSC which the included crack file makes into a LEGAL :lol: version of the embedded IoT version. And this version is supported by microsoft until 2032... By then I will have 11 LTSC.

So yu need a few things to make everything work.
1. A copy of LTSC
2. The MAS 1.8 or newer (the "medicine"...)
3. A small program to disable the damned built in anti virus so it doesent keep deleting the medicines... You dont need any antivirus RUNNING in real time at all. I havent used one in decades. I periodically run one as a check but never a problem. I exclude anything that is a crack or a "medicine"...
4. MS Office latest...
5. Adobe Photoshop, adobe raw, adobe Premier, etc etc. And a load of other stuff.
6. FIREFOX latest with UBLOCK ORIGIN installed so no ads ever.

EVERYTHING is "free" if you know how. And I know how.

So what do you need?
I can upload it to a file sharing site...
But it takes many hours so let me know.
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Re: Group 24 cells

Postby jefferso » 20 Jun 2024, 01:41

I think all I really need is Windows itself, so 1, 2 and 3 in your list.
I would only use the Windows to run the PL8 software.
It worked fine in a Virtual instance of Windows last time I had it running. I haven't connected to the PL8 in a while, I've just been using it with an SB50 plug in my old Permobil C500 which starts up by pressing enter a bunch of times on the PL8.
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Re: Group 24 cells

Postby Burgerman » 20 Jun 2024, 02:32

Will do it in he morning...
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Re: Group 24 cells

Postby Burgerman » 20 Jun 2024, 14:16

Half uploaded. FTP server to my webspace/hosting in USA...

Will post link when complete...
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Re: Group 24 cells

Postby Burgerman » 20 Jun 2024, 16:01

Done...

http://www.wheelchairdriver.com/doomed/

Grab all. They are zipped so your existing anti virus doesent spot all the various cracks and stuff and delete them before you can stop it. Or before your safety nazi browser detects a "dangerous" download. Trust me they are not!

Will delete in a few days. Let me know when you got them.
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Re: Group 24 cells

Postby jefferso » 21 Jun 2024, 00:54

Got them, thanks!

Here's the arrangement with interconnectors.
Once I get the Windows running I'll connect to the PL8, attach the balance wires and try a test charge.


IMG_2537-arrangement-interconnected.JPG
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Re: Group 24 cells

Postby Burgerman » 21 Jun 2024, 02:21

The metal case of these cells are connected to the negative terminal Since they all get connected in series that means each case is 3.3V different to its neibour. So you need some tough but thin insulation layer etween each one, and around the outside. And underneath.

A tough close fitting polythene bag would work. Or thin plastic sheet. Etc. For safety.
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Re: Group 24 cells

Postby jefferso » 21 Jun 2024, 21:19

I got the Windows to run in a virtual machine. I had some trouble because I couldn't figure out how to make the files into a bootable .iso. I found another bootable installer .iso, installed, then mounted the files and was able to re-install the good version over it.
The CHGM8Sv2 app works, but I haven't had a chance to plug in the PL8 usb to it yet. I have a few profiles I downloaded a while ago from here including "LiFe Charge 8S 230AH Pack.PS8". I should be able to load that and use it for the 160Ah pack right?

For insulation I have 8 thick plastic sheets which Docan Power sent (photo below). They're big enough that I thought I could fold over the bottom and cover one side and the bottom, but they're too stiff to fold and crack if I try, so I'll cut them to be the right size for in between, then for the bottom and outsides, I got some 240 micron acetate sheets which I'll tape in place.

IMG_2469-insulating-sheets.JPG
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Re: Group 24 cells

Postby Burgerman » 22 Jun 2024, 01:51

Sounds all good. Except one thing.

Better to junk that nonsense you got the virtual machine running on and natively install Win64 IoT LTSC...
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Re: Group 24 cells

Postby jefferso » 04 Jul 2024, 19:48

I finally had some time to get the cells together with the plastic between them and the balance wires connected. Reads 26.38v
Hopefully soon I'll be able to set things up for a test charge.

IMG_2709-connected-balance.JPG
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Re: Group 24 cells

Postby Burgerman » 04 Jul 2024, 19:51

Hopefully those crimps are also soldered?

If not then expect balance issues or worse if not now then later on.
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Re: Group 24 cells

Postby jefferso » 04 Jul 2024, 19:54

Those are highest quality shirley_hkg interconnects. I expect no issues.
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Re: Group 24 cells

Postby Burgerman » 04 Jul 2024, 19:56

I thought I included the ISO file in that windows rar file? Maybe not...
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Re: Group 24 cells

Postby jefferso » 04 Jul 2024, 20:04

Burgerman wrote:I thought I included the ISO file in that windows rar file? Maybe not...


No, it was all the necessary files in the zip, but not in a bootable .iso file.
I got there in the end, thanks again!
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