Do you use every cell chemistry in your packs?


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drbacke

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Apr 3, 2019
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60
I'm currently harvesting used cells and asked myself wether to use every chemistryor not?
I don't mean mixing different voltages (only NCA, NMC, LCO, LMO) and of course only tested cells.
LCO and NCA seem to be the most dangerous types, but otherwise most NCA cells are of newer date (personal experience, maybe a coincidence).
What do you do and whats your opinion to that topic?
 

Wolf

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Sep 25, 2018
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1,760
drbacke said:
I'm currently harvesting used cells and asked myself wether to use every chemistryor not?
I don't mean mixing different voltages (only NCA, NMC, LCO, LMO) and of course only tested cells.
LCO and NCA seem to be the most dangerous types, but otherwise most NCA cells are of newer date (personal experience, maybe a coincidence).
What do you do and whats your opinion to that topic?

Good question.

What I am doing is sorting my batteries by low drain(LCO, NCA) and high drain(LMO, NMC) chemistries.
As I am harvesting more (many more) of the low drain chemistries mostly from laptop and medical packs and some high drain chemistries from power tool batteries my power wall will consist of all low drain batteries. My aversion to using high drain chemistries in my powerwall packsisthat the IR is so much lower in these batteries that I feel there would be an imbalance inthe pack. Most manganese and manganese-nickel based batteries have a very low IR and support high discharge rates which is good if you are Vaping (not my thing) or high draw power tools (my thing).IR on those cells usually is in the <25m? range.
The low drain cobalt and aluminum based batteries have an IR that is much higher as in the 35m? to 90m? range. So my consensus is that I would like to keep the IR of my individual cells in my packs as close together as possible. My thinking is 35m? to 75m?. That will give me an even charge on the pack and keep the parallel side balanced.

If I had a tremendous surplus of the high drain chemistry cells I would then build a powerwall using just those. In my case I do not and will use these cells in other projects as in small power banks for cell phone charging, A nice 4s10p ~14.4V Battery pack for spot welding with the Kweld,Jump-starting a car etc.

Wolf
 
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Overmind

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Jan 16, 2019
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457
@Wolf I also use a medium drain category (like the Sony V3s or red 2150mAh Sanyos.).
 

Wolf

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Overmind said:
@Wolf I also use a medium drain category (like the Sony V3s or red 2150mAh Sanyos.).

@Overmind
I haven't seen any Sony US18650V3s 2150mAh cells in my travels but I do have a bunch of Sanyo UR18650FJs 2100mAh,(some claim 2200mAh)I assume you are talking about those as they have a Orange/Red Insulator,cells.
The UR18650FJ is a really good cellunfortunately it has only 2100mAh so it doesn't meet my 2200mAh tested criteria. It does have a higher than normal IR but I wouldn't shy away from it in a powerwall build If your criteria is 1700mAh and above.It looks like the cells perform adequately up to75m? the lowest one I have so far is 59.5m? with perfect results. So I would not have a problem adding this cell to a mix of other chemistries.
Standard charge is 1C 2100mA and standard discharge is 0.2C 420mA also cutoffis at 2.5V.

Wolf

image_fqpmvz.jpg
 

Overmind

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Jan 16, 2019
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To clarify, Sony V3 is 2250mAh (would meat your standard).
The red Sanyos with pink cap are officially rated at 2150, but since my quality categories have a threshold at 2000mAh, they fit fine at above 2k.
 

Wolf

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Overmind said:
To clarify, Sony V3 is 2250mAh (would meat your standard).
The red Sanyos with pink cap are officially rated at 2150, but since my quality categories have a threshold at 2000mAh, they fit fine at above 2k.

Ah yes the pink cap Sanyos I see them every so often but not that many.
The Sony V3 non existent in my timeline.
Ah I see the rated capacity is 2150mAh but the nominal capacity is 2250mAh Sony cant make up its mind. Shheeeesh.
Wolf

image_tyuyuf.jpg
 

Generic

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Oct 23, 2018
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Personally, I'm not putting any high drain cells in my powerwall, those get separated for high drain applications (lawnmower, snowblower, power wheels, etc.) In my generic powerwall, the low drain cells get additionally sorted by nominal voltage (3.6V and 3.7V cells get separated) and cell model (5 models account for 75% of the cells I harvest). Not really recommending that way, that's just what I'm doing, since you asked.
 
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