Using Donor LIPO Cells with Individual Integrated BMS Per Cell for a DIY Pack?

[Hillhater]

You certainly need to find a way of reliably connecting EACH of the individual cells in the 10.4 Ah pack in parallel such that each cell is charged/discharged evenly.
..unless you are prepared to tear a pack down and test an individual cell ?
Get yourself a data logging RC charger to help test the cells

 

[john61ct]

Will do.
I'm sure there's a significant amount of info on here regarding equipment options for testing/charging these. Is there anything specific to these cells that I should know about/take into consideration when looking into equipment?

Started a "collection" thread dedicated to such questions

https://endless-sphere.com/forums/viewtopic.php?t=103013

 

[LanM]

Will do.
I'm sure there's a significant amount of info on here regarding equipment options for testing/charging these. Is there anything specific to these cells that I should know about/take into consideration when looking into equipment?

Started a "collection" thread dedicated to such questions

https://endless-sphere.com/forums/viewtopic.php?t=103013

Excellent. Thank you John.

 

[LanM]

You certainly need to find a way of reliably connecting EACH of the individual cells in the 10.4 Ah pack in parallel such that each cell is charged/discharged evenly.
..unless you are prepared to tear a pack down and test an individual cell ?
Get yourself a data logging RC charger to help test the cells

I believe someone said I should never open the silver packs. OK, just so I understand this:

Each cell inside the packs needs to be individually balanced? So the connectors get chopped regardless. I'm emailing the manufacturer with a few questions to assist in defining the composition of these things.

It it an unusual setup to have these multi-cell packs operate like this, or is it because this project has a much higher draw than the tablet it was in? I guess another way to ask is would the tablet these were mounted into balance these cells?

If I'm making a 14S pack, if there are 3 cells in each pack, will my 14S be 14 of these packs, or 14 of the individual cells in this pack (5 packs which would be 15). And does that mean the last one is left dead or will I have to make a 15S pack due to the structure?

 

[Hillhater]

From The image, it appears that each cell in the 10.4 Ah pack is individually wired to that connector.
Often, laptops and tablets have the BMS functions (balancing, LVC, HVC, Thermal monitoring, etc) all on the device, rather than the battery,..hence the multi wire connection from the individual cells in the battery.
So you either find the mating connector, or cut (very careful !) and discard that one.
But either way i do not suggest you attempt to separate the cells out from the packs..(high damage risk)
You will need to check the voltage of each individual cell and if necessary equalise them such that you can connect the cells in parallel.
Once all the +ve and all the -ve wires for the individual cells are connected you can treat it as one 10.4 Ah cell for testing.
Your 14S pack will need 14 of these “bricks” in series...and depending on how they test out, you will have to have multiple “bricks” in parallel at each of the 14S connections.
You have a lot of testing, and wiring connections to make since your chances of finding a suitable ready made harness is less than none !......and you do not want to risk a “lazy” or dud cell anywhere in that assembly of several dozen cells.

 

[john61ct]

Yes, each cell needs individual care, or at least each paralleled group at the bottom-most level.

The physical "packs" of multiple cells are just physical packaging, irrelevant to the logical / electronic design aspects.

No problem testing each individual cell, long as those wires are connected to each individual cell directly, no "protective" chips inside.

Just make use of those existing wires, even if their max current-carrying spec becomes your limiting factor.

You can arrange your xSyP any way you like, no reason to use that idea of treating each pack as a single unit, work at the cell level.

That way, mix & match your "xP virtual groups" to balance performance (capacity / resistance) between them, even bypassing individual bad cells if any rather than discarding the whole pack.

None of this requires breaking any of the physical packaging.

> I'm emailing the manufacturer with a few questions to assist in defining the composition of these things.

Don't expect any support there, but worth a shot I guess.

 

[LanM]

Thanks for the info guys.

I am a little confused on the wiring description, as it seems that Hill is describing potentially wiring the 3 cells for each pack together and treating it as 1 cell vs John's description of treating each cell as individual.

Would they only get wired together so each pack is treated as 1 cell if they all are balanced, and otherwise wire each cell individually so potentially bad cells can be skipped but keep the pack itself?

From the photos, does it look like there's just 2 cells? I know there are 8 wires, 3 pos, 3 neg so does that mean there are 3 cells per pack? Any idea on how to figure out what the 2 other wires are for? Is there a safe way to dissect one to figure it out?

 

[john61ct]

I am a little confused on the wiring description, as it seems that Hill is describing potentially wiring the 3 cells for each pack together and treating it as 1 cell vs John's description of treating each cell as individual.

That's because we're offering different approaches, waddya expect, a consensus? Not the way forums work

**If** the cell count per package happens to coincide with the xSyP layout you end up choosing,

and all the cells turn out to be matched and healthy

sure you could use the packages as units to fit your layout.

I personally would treat the cells individually and leave the packaging irrelevant.

When you get the boxes home, a DMM will reveal (some of it) all, but yes certainly likely cell count per package.

 

[LanM]

Ha, yeah I definitely didn't expect a consensus.
I guess its just a waiting game until I get them home at the moment.

I'll be following your new thread, and putting together the equipment I'll need for the build.

I'm guessing I won't know much until I have answers about how these cells test out. If I end up needing a massive pack, it may change my intended build. It would seem a waste to not take advantage of the volume of cells I have on hand. Maybe I'll end up building multiple packs and alternate their days' use to stretch out the life vs having leftover cells age on the shelf.

 

[john61ct]

Or build some nice packs for portable solar storage, camping, vans etc and sell them at a profit, enabling you to buy some really great high-performance brand new cylindrical cells well suited to feeding a very powerful ebike

 

[flippy]

Will do.
I'm sure there's a significant amount of info on here regarding equipment options for testing/charging these. Is there anything specific to these cells that I should know about/take into consideration when looking into equipment?

these are unknown cells.

if you have -that- many you can afford to lose a couple.

i would recommend sending a couple to someone here that has the equipment to test these cells for you and give solid recomenddations.
i can do this but i am based in the EU, so i would look for someone in the US that has the proper equipment and knowledge. its a pretty small list as testing equipment is really expensive.

 

[LanM]

Or build some nice packs for portable solar storage, camping, vans etc and sell them at a profit, enabling you to buy some really great high-performance brand new cylindrical cells well suited to feeding a very powerful ebike

As entrepreneurial as I have traditionally been, I hadn't considered that route. I'm assuming that may be a viable option since these seem to be a decent quality cell. I see them being sold on ebay and the like for $35-45 each (absolute highway robbery). I assume the bulk of that price is solely for the specialized connector/ oem fitment need otherwise there seems to be nothing special about these.

 

[LanM]

these are unknown cells.

if you have -that- many you can afford to lose a couple.

i would recommend sending a couple to someone here that has the equipment to test these cells for you and give solid recommendations.
i can do this but i am based in the EU, so i would look for someone in the US that has the proper equipment and knowledge. its a pretty small list as testing equipment is really expensive.

I certainly would be happy to take that option should that be on the table for someone. My only question would be: based on John's and others' advice it seems like I'll need my own testing equipment to test each individual cell prior to pack construction. I haven't dove into the differences in equipment for each step of this process yet, so I am unsure whether I can get away without purchasing the equipment myself.

 

[flippy]

if you have a baseline you only need basic tools and instructions to weed out the bad cells.

 

[john61ct]

The nice thing about having at least the basic gear, is that as you wear out the packs, you can make an informed judgment on EoL replacement time, see how different usage/care standards impact longevity, continue to educate yourself and others as you work with other cells.

With buying platforms supporting decent guarantee policies, you can take a chance on a maybe dodgy deal, do a standard test upon receipt, and then if no go, just send them back with proof they were "not as described".

 

[Hillhater]

Some online digging reveals little real data on these cells, other than a box of 40 of them weighs 8.2kg ...
..and also acording to the packing label they are a 1s, 2p pack !! :? Suggesting 2x 5400mAh cells
...which just makes the 8 wire ,( 3 red, 3 black ) connector even more mysterious.
https://www.auctionsinternational.com/auction/16961/item/new-li-ion-batteries-103681/basic

 

[LanM]

John, yes with the volume of cells I have it will probably be in my best interest to get setup properly with gear. I'm following the thread you created and I'll hopefully get a clear picture of what I should have with relative affordability to get this project rolling.

Hillhater,
yes those are the ones. Same auction house mine are from. Picking up by the middle of next week. My lot is 350pcs, a mixture of those cells and 2 other types.
What are the implications of having a 1s2p pack arrangement?

 

[john61ct]

maybe multiple packs per tablet.

more wires likely just gives more flexibility, in vs out, lets you go to higher amps per cell, monitoring separate from supply, who knows, wait and see

 

[john61ct]

What are the implications of having a 1s2p pack arrangement?

None, if the wiring is per cell may be able to do 2S1P or arbitrary just treat each cell as a cell.

If the 2P connection is under the silver packaging the leave that as is of course, just treat as one cell with double the mAh capacity.

 

[Hillhater]

I am struggling to understand why a 2 cell pack has 8 wires connecting it to its host device. ?
4 would be obvious,
2 more for thermal monitoring
2 more ....???
Let us know when you get your hands on one.

 

[LanM]

Will do, I guess its a waiting game at the moment.

I'm assuming if 2 of the wires are for thermal readings that would be a good thing, right?
This cell has twice the amount of wires as I'd normally expect right?

EDIT**

 

[LanM]

Update- I picked up the batteries today. I carefully peeled back the covering and took some photos. Hopefully someone can make heads or tails of the board attached to them.
breakdown:
1S2P
3 positive, all originating from the same solder point
3 negative, same thing.
White wire originates from a point labeled "T" -which I'm assuming is temperature.
Yellow wire originates from "ID" on board. No idea what this wire is.

View attachment 3




Does this mean that each one of these cells have a built in BMS?

 

[LanM]

When I begin testing these, would I solder the 3 leads of each polarity together and use that, or do I have to open each of these cells to remove that board? I'm not sure if what I'm assuming is a built in bms based on a few online searches.

I'm guessing it is a bms based on the labels on the pcb, R1, R2 (resistors), C1,C2 -capacitors. I've seen several different references to the "U" on the board being a label for an integrated circuit, and also one other document referred to it as a mofset. No idea what the yellow wire is. Is there a way to test that/figure it out?

Does anyone know what I might start at for charging voltage? I considered looking up the laptop these likely went in and using that as a baseline for charging voltages.

After reading the other thread on equipment, I'm gravitating towards a cellpro powerlab
I'm also probably going to purchase the cheapest, simplest setup to test a random sample of these packs to verify condition, not that I'm all that concerned since they were actively being used in production.

 

[LanM]

Almost ready to start testing.

picked up an icharger 106b+, with CB1010 balance board. Still need to figure out which connectors to order to wire to battery/plug into balance board.

Testing will start with 1 individual pack, leaving it complete with whatever built in bms it has. I'm assuming that will do no harm.