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So your expecting to use that extra? That is like adding a couple more batteries to your pack because your controller can handle two more batteries but it's pushing the threshold. I buy 100 AH cells and if there is more in there then great. They are not 210 or 220 AH cells, they are 200 AH cells. There is built in extra so you can use that to your advantage. Well if you need to know how well balanced they are why not ask them. I won't use my cells in that manner. I will build for a 200 AH pack, not a 210 AH pack. So all the cells do fit within the 200 AH range so are matched quite well. If you match them at 210 then the 200 AH cells are lower capacity and those are your limiting factor. So you have cells at 210 and 220 and all are in this range? You do have a fully matched 200 AH pack. If you want 220 AH cells then you must contact them and order a fully matched set at that AH range. It will cost you, I guarantee you it will. If I find my cells are in the 90 to 100 AH range then I have a pack that is balanced at 90 AH and not at 100. If I have a batch of batteries that are over 100 AH then I have a pack that is balanced at 100 AH. So I don't use the extra. No big deal. I only paid for 200 and planed on 200 so I put it all together at 200. All will provide 200 AH. That is good.

Pete :)
 
You do know that Winston Battery company is the leader in these cells. What makes you think that they are not balanced from the factory in voltage and AH ratings? More likely who makes you think that? Who are you following? The Trolls (who by the way have taken over a few forums but left their mark) or those who are really doing and showing?

Aren't you running lithiums?

PS. Did you notice how quiet the forum has gotten since the main daddy trolls left?
 
You're missing the point. No I don't use the full capacity potential most of the time. However the farther apart the cells are in actual capacity the different SOC each cell will actually operate at. If you have 100 ah cells where some are at 110 ah and some are at 120 ah, even if you only charge to 100 ah that means the 110 ah cells are at a higher SOC than the 120 ah cells. That also means the smaller cells will be putting out higher relative C rates than the large cells at the same current draw. All this can add up to different aging characteristics over time, which is probably why Jay emphasized matching cells. He's the expert, not me, I'm just following his advice. As for capacity variation for TS cells I'm going by what people have been reporting, just as I'm going by what people have been reporting for recent CALB orders. Maybe TS has improved their cell matching for each order, but I have not yet seen reports of such. I'm well aware of the relationship between CALB and TS, the fact is that CALB had better QC and cell matching than TS at one point, regardless of who licenses what.
 
If all my cells are rated at like 110 and all fall within that 110 range + or - a few AH's and I put in 100 AH then That is all they will have in them. They won't have more than what I put in. If I have a glass that can hold 110 ounces and I only put in 100 then 100 is what I get out. They will always hold that if my filler container can only hold 100 ounces. I fill up each cell to 100 and that is all each will give. I just have some spare room. So it won't matter if a cell can hold extra cause your not using it, right?

I think I have the point pretty clearly.
 
I'm going by what people have been reporting
Yea! My point is WHAT people are reporting that? Are your batteries capacities that far out of whack? Very very doubtful. Mine on the other had are but only because some were abused badly and have a lowered capacity. I must cull out those with capacities way lower than the rest. Mostly I have found only a couple and the capacity is not off by much. The SOC is off by a lot but that is being fixed. I still have a bunch of cells that are needing balancing because of past abuse and were used with a malfunctioning BMS system. It is just time consuming to bring the SOC to a respectable level and then charge the packs. I am leaving many alone for now while I mess with the MG and Ghia. I am not putting on loads of miles either right now because of weather. The open MG is not the most fun in cold wet weather. We are getting a good soaking this week.
 
If all my cells are rated at like 110 and all fall within that 110 range + or - a few AH's and I put in 100 AH then That is all they will have in them. They won't have more than what I put in. If I have a glass that can hold 110 ounces and I only put in 100 then 100 is what I get out. They will always hold that if my filler container can only hold 100 ounces. I fill up each cell to 100 and that is all each will give. I just have some spare room. So it won't matter if a cell can hold extra cause your not using it, right?

I think I have the point pretty clearly.
As far as capacity goes, that is correct, it won't matter because they will drain down at the same rate but if you have one that has a capacity of 110 when fully charged and one that is 100, when you draw them down and you are pulling, say 300 amps, you draw 3C from a 100Ah cell and 2.7C from the 110Ah cell. The 100Ah cell will generate slightly more heat which is wasted energy and slowly over time that wasted energy adds up to imbalance. The bigger the capacity difference or impedance mismatch with a pack, the bigger difference it makes. Of course usually you don't draw constantly at a high rate to where the cells get hot so its not as big of a deal as you might initially think but its a factor. If you had a bigger disparity amongst the pack, it would require a little more attention every xx cycles. This is the primary source of lithium cell drift, there isn't much of it, but its there, energy lost at heat with different rates between cells.
 
I think I have the point pretty clearly.
No I'm afraid you really don't. Read my last post again. Different sized cells filled with the same amount of amp hours will be at different states of charge. That is an imbalance that will be repeated every cycle and possibly be amplified over time. Minimizing this difference seems prudent, and what the OEM's are doing. We want our cells to all behave the same, the best way to do that is for them to have the same capacity and ideally the same internal resistance. My pack of SE/CALB cells came in between 110 and 114 ah actual two years ago, pretty close, but newer CALB shipments have come in with less than 1% variation, even better.
 
Oh yes I do. If I fill each cell to it's own capacity then I will have troubles if my capacity is different and I drain to the end of that in a pack that is strung together. In reality that is not what happens. We charge the pack as a whole.

Say I have a pack of 10 cells that range in capacity of 110, 109, 110, 104 and so on for all 10 and I put in a 100 AH level all at the same time in the string then the total fill level will only be 100. Not 110 or 109 or any such thing. If my stop level is 100 then ALL cells will be at the same capacity all the time every time if I use 100 as my stop level. If I change that level to 105 then some of the ones that are 104 will overflow or overcharge. But we don't charge cells one at a time now do we. We charge them in a string as though it is one single cell of a specified voltage and if you put in more than the minimum cell can hold then you over charge those cells. If all the cells can safely hold 100 or 200 AH then ALL the cells will MATCH in capacity but in reality they all can hold more. If I fill them to the same level each time and I leave enough safe room then the changes in temp and other factors then all the cells will maintain a balance. So far no one has really found that these imbalance due to the variances but the theory is sound. Even your saying its possible and not for sure. If it ever becomes a problem it is most likely that the cells are reaching the end of life anyway and its time to change them out. This is after many years of successful driving with no apparent discrepancy in balance.

There is no imbalance if one fills to a safe level. But if you insist that you take the cell to the limits then maybe you will have troubles. Maybe.

A 200 AH cell is showing 220 AH but since they are 200 AH cells I set my limits to 190 AH for both charge and discharge cycles and live in that zone. There will be no problems. Sure I am not using the full capacity of the cell but that is the goal too. Longer cell life.

Pete :)
 
the best way to do that is for them to have the same capacity and ideally the same internal resistance.
In a perfect world. Yes that is true but what we are getting IS GOOD ENOUGH. So you really tested them all? Real accurate or guesstimate? Within those ranges of AH capacities your SOC will be so close and if you use the same method to charge each and every time you won't have trouble.

I guess it is really important to be anal about making sure all our batteries are absolutely perfect in capacity and resistance. So if you really need that level of accuracy then you need to work with the company to be sure all cells are all fully matched and perfect for every order that comes out of the doors. There is fudge room for a reason. It might be needed to have that level of accuracy if we were talking about taking these to mars. But for our cars on the street the accuracy is not required.

Pete :)

SOC is relative anyway.
 
In a perfect world. Yes that is true but what we are getting IS GOOD ENOUGH. So you really tested them all? Real accurate or guesstimate? Within those ranges of AH capacities your SOC will be so close and if you use the same method to charge each and every time you won't have trouble.

I guess it is really important to be anal about making sure all our batteries are absolutely perfect in capacity and resistance. So if you really need that level of accuracy then you need to work with the company to be sure all cells are all fully matched and perfect for every order that comes out of the doors. There is fudge room for a reason. It might be needed to have that level of accuracy if we were talking about taking these to mars. But for our cars on the street the accuracy is not required.

Pete :)

SOC is relative anyway.
I wouldn't call that anal but the closer they are matched, particularly in IR the longer they will stay in balance which I think is a good thing. Mine all came in at .025-.030 with the vast majority .025 & .026. I added a spare at the last minute and it was tested at .036! At first I thought that wouldn't be good if I mixed it in but likely by the time I need to use it, the IR of the others will have increased due to age and ???
 
Oh yes I do.
No you don't. The amount of charge you put in does not change actual capacity. That's like saying if you fill an 8 ounce glass half way it's now a 4 ounce glass. If you put 100 amp hours into a cell that can hold 110 amp hours and another that can hold 120 amp hours the smaller cell is at a higher SOC, period. We know that the more charge you put into a cell the less cycle life you have, so each time you are putting more relative charge into the 110ah cell than the 120ah cell. That means the smaller cell will degrade faster by being more fully charged than the larger one over time. This assumes bottom balancing of course. Top balancing puts all cells at the same SOC but the smaller cells will be more deeply discharged each time, which also shortens cycle life. The way to avoid both problems is to get cells as closely matched as possible. CALB ships all cells with data sheets showing actual capacity and internal resistance so you know what you are getting. Does TS do the same? Additionally Jacks testing showed the CALB cells to have flatter discharge curves, if he didn't get the free donation from Winston he'd be using CALB as he originally planned.
 
I do. It is only relative. That 110 AH cell CAN hold a higher SOC but if I do not put in that extra it is not at a higher SOC. SOC refers to the state of how full a cell is during the charge or discharge of the battery.

Relative to each other yes but we are not using the SOC. It is only a meter to tell us how full or empty a cell is from our fill level. It does not matter. Since all are filled at the same time the level is the same. They will empty pretty much the same too.

I am very aware of the relative aspect but I am talking of what we actually use. If all the 110 AH cells are filled to 100 and that 200 AH cell is filled to 100 then we have a relatively 100% full Pack.

If I put into my pack a 200 AH cell and charge the pack of 100 AH cells then relative to the 100 AH cells the 200 AH cell will be at 50% SOC. That cell won't take the brunt and drain in half the time. It will just never be more than 50% charged and will live quite happy with the batch of 100 AH cells.

So there is nothing bad happening here but you make it sound like there is.

A major difference in IR may be an issue but I don't think it will be as big an issue as your making it out to be. Sure it is good to be as close as possible to ideal and I think the ideal is already in play. It will never be perfect but so far no one has complained about IR being a real issue. Could it be? Sure. Is it? Most likely not. Will cells drain a touch at differing rates? Yup. It's like that with all chemistries. Internal Resistance is a player but if you don't abuse the cells and run them in the range expected from the manufacturer they will be just happy as little clams on the beach. The manufacturer knows the differences and has given a parameter range in which to operate the cells. If you go out of the range you can run into trouble. It is up to you to set up your pack so it will stay within that range with known issues.

As the cells get better and things get more accurate the parameters will change and our setups will change. But you will always have to run the cells within the parameters of the cell no matter what. Go out side that mark and your asking for trouble. We have lots of guys wanting to take them outside that parameter and that is not a good thing.

It's always push to the limits and bitch when it does not work.

Pete :)

Enjoy your cells as they were designed. The surpass all others that have been available to the public. But in the end it is never enough is it!
 
CALBS are used in Aviation and as such the aviation industry is always more anal about precision so it is no wonder that CALB is a bit more accurate and refined. Also more expensive. So in order to get the better you will pay more. like I said and another too. What we have IS GOOD ENOUGH. It will get better. But even in its early days these cells surpassed any other ever available to the public. Note I said (PUBLIC)
 
You still are not getting it. A 110ah cell charged to 100ah is at a HIGHER SOC than a 120ah cell charged to 100ah. Let's make the math really simple. A 100ah cell charged to 90ah is at 90%SOC. That same cell charged to 80ah is at 80%SOC. 90%SOC degrades a cell faster than 80%SOC. Same thing is happening with the 110ah and 120ah cells, the smaller cell is at a higher SOC than the larger one when charged to 100ah, or 90ah, or whatever. The smaller cell will always be at a higher SOC than the larger one when filled with the same amount of amp hours.
Yes today's cells are good enough, never said they weren't, but to make them last longer, and to make it easier to do so, it's better to get them as closely matched as possible, just as Prof. Jay recommends and just as the OEM's are doing. We should all request cells as closely matched as possible from all suppliers. More educated and demanding consumers leads to better products.
 
A 110ah cell charged to 100ah is at a HIGHER SOC than a 120ah cell charged to 100ah.
Relative to the 110 AH cell. In use we still can only take out 100 AH because that is all that was put in. Yes the 120 AH cell will last longer by a bit because it is being used at a lower total state than the other. This is where the fudge factor comes to play with a pack that has varying capacities. Fill the smallest one to a safe level and the rest are just along for the ride.

I agree that the closer the capacities and IR the better.

Never thought different. What I get is that folks talk like it is going to be a problem. Well if you don't do things correctly then yes.

So, Yes I do understand. I have always understood. Pretty simple really.
 
If you had 10 buckets with the same diameter and one holds 5 gallons of water before spilling over, but the rest were all taller in some way, and you had them all connected at the bottom.....now you fill them til the 5 gallon bucket was full....you would have a total of 50 gallons of water available.

The taller buckets have no meaning, for all you can get out of the total, without spilling one over, is what the smallest bucket can hold.

If you have an empty battery pack of 100ah batteries, and you charge them to the 100ah rating, or to the smallest one in the pack, its full.

The few that are some amount higher, are not usable, no matter if you bottom balance or top balance. The only SOC one is concerned about is whats usable.

Roy
 
If you had 10 buckets with the same diameter and one holds 5 gallons of water before spilling over, but the rest were all taller in some way, and you had them all connected at the bottom.....now you fill them til the 5 gallon bucket was full....you would have a total of 50 gallons of water available.

The taller buckets have no meaning, for all you can get out of the total, without spilling one over, is what the smallest bucket can hold.

If you have an empty battery pack of 100ah batteries, and you charge them to the 100ah rating, or to the smallest one in the pack, its full.

The few that are some amount higher, are not usable, no matter if you bottom balance or top balance. The only SOC one is concerned about is whats usable.

Roy
What then is the effect on battery life in that scenario (overall pack and individual cells)?
 
The cells with more available capacity will last longer due to not being charged fully. In other words the SOC is lower than the ones that hold less. But the ones that are pretty much near full SOC will last the normal life span. The others will give more. It is best to have each container hold nearly the same so after a full life the cells are still pretty much balanced. From the factory they pretty much are the same. I think that the IR is the more critical part of this equation.

It is interesting to note that I have a cell in my pack that will jump in voltage to a higher level before the others but in the end it was nearly the same before shutting down the charger. That cell has a spot that will just jump then settle down to the level of the others. It is interesting to watch the cells charge up. They don't charge at the same rate but pretty much close.
 
The only SOC one is concerned about is whats usable.

Roy
I'm not talking about using the extra capacity of larger cells, you're missing the point. Percentage of charge has an effect on the battery. The greater percentage you fill to the greater the effect on cell life. The greater percentage you discharge to the greater the effect on cell life. SOC measures percentage, not amp hours or capacity. With a bottom balanced pack a 100ah cell charged with 100ah's is at 100% SOC. A 110ah cell charged with 100ah's is at 90% SOC. Same amount of amp hours, different SOC. The larger cell charged with 100ah's at 90% SOC will last longer than the smaller cell charged with 100ah's at 100% SOC because the higher the SOC the greater impact on cell life. Again, this example applies to a bottom balanced pack. If top balanced then the imbalance shows up on the bottom when discharging. The 100ah cell putting out 100ah's ends up at 0 SOC and the 110ah cell putting out 100ah's ends up at 10% SOC. The cell with the lower SOC also negatively affects cell life. Over time these differences will add up and cause cells to age differently, which will further accelerate those differences. No BMS can counter that effect but getting closely matched cells to begin with can. Smaller capacity cells will always use a greater percentage of their capacity however they are configured, and the greater percentage of capacity that gets used the larger the effect on cell life.
 
Yes the 120 AH cell will last longer by a bit because it is being used at a lower total state than the other.
This has been my entire point. Smaller cells will age faster than larger ones, which will in turn reduce their capacity more, accelerating the difference. Undercharging everything helps but cannot eliminate this difference, the large cells charged to 70% will last longer than the smaller ones charged to 75% for example. Over time this difference will still increase. Minimize these differences enough by getting closely matched cells and it won't be an issue. I'm guessing around 1% difference is good enough but at this point we don't really know.
 
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