[JRP3]

Let me also point out an easy way to know your cell capacity is to bottom balance your pack. Once you have them all discharged to the same SOC you monitor them when charging. When the voltage starts to shoot up on the first one, (around 3.50 for SE/CALB), you know it's reaching full and you know it's your smallest capacity cell. Using an amp hour meter you know how many amp hours went into it. Also, my SE/CALB cells all came with a data sheet listing actual capacity and resistance for each cell, tested at the factory. I guess HiPower doesn't do the same? You can also use a $30 Cell Log 8 to log 8 cells at a time to see how they behave under load.

 

[JRP3]

I have a friend who installed Hipower 300V100Ah battery pack, he had put 496 miles on the pack for one charging.

Just to be clear, the 496 miles were not done on one charge, but many charges between 40 and 50 miles each.

*Ah Major beat me to it.

 

[JRP3]

if you feel convenient, you can send the request for 100Ah Spec by Email , my Email adress is [email protected] .
if you want to buy cells, you can buy from Carl Clark, 001-8012435300
--

Keep Smiling & Never Give Up !!!

TKS & Best Regards

Candy Yan

008613874997703​

If you just post the specs here on the board then everyone can see them.

 

[JRP3]

Thank you. Is each cell tested for actual capacity and internal resistance, do they come with a data sheet with that information, and how close to each other are the cells in capacity? For example, my SE/CALB cells each had a serial number and a data sheet referencing tested capacity and resistance. The 100ah cells all were between 110-114 actual capacity. Closer grouping of capacity would be preferred and make management easier.

 

[JRP3]

hello to all

on our new pack we got a test sheet and a serial # sheet. the test sheet showed that the pack had 213 amphr per cell.

thanks kevin constant
topeka electric motor inc.

Each cells was exactly 213 ah? Do they all discharge and charge to the same value? Have you pulled the whole pack down below 3.0 volts per cell?

 

[JRP3]

Dear JRP3,

Hipower battery is somehow different than Thundersky or CLAB, We use "Aqueous solution" technology, it is more suitable for electron translation in Aqueous liquid, the charge and discharge ability is better than "oily solution", and it is more safe. The "Aqueous solution" is translated as Chinese mean, I don't know the real English word is. However, this improved technology really have better discharge curve, and it is easier to control cell's quality as electrical property of cells in producing, cell would have more "same" property as IR, charge / discharge characteristic.

I think what you are saying is that your electrolyte is water based as opposed to petroleum, or oil based.

 

[JRP3]

She asked me to keep it off the forum and I may buy so ill honor that, just to say that its a *bit* less then TS or CALB for what, according to the specs seems like somewhat lower ratings.

She is friendly and fast with a response, hit her up

I don't understand why certain sellers like to keep their price a secret. Other places publish their prices and shipping details so buyers can compare.

 

[JRP3]

The other factor to consider is cell matching. So far from what I've seen CALB has the edge on that. I actually consider close grouping more important than the difference between 3000 and 5000 cycles, since 3000 cycles on a 50 mile pack is already 150,000 miles, and an imbalanced pack can kill cells quickly.

 

[JRP3]

I'll disagree. Closer capacity makes management much easier. Matching your cells closely makes life easier and less likely to damage an individual cell. I'm not talking about getting extra capacity, I'm talking about getting each cell capacity to closely match all the others. I'd much rather have all my cells at 210ah instead of a range from 210-220 since the extra capacity of those over 210 can't be used.

 

[JRP3]

I'm talking about the extra capacity between 210 and 220 ah, you can only use up to 210 ah. Simple fact is the cells will likely track more closely over time if they are at the same capacity. OEM's are concerned with matching cells and so should we. Remember the video from Jay Whiticare and what he stressed? Match those cells. I'm taking his advice. Until someone reports what their batch of TS cells come in at we don't know how close they really are. We do know how close the recent batches of CALB's are, and we do know that previous batches of TS cells have not been as close. Hopefully the new ones are closely matched. Pick whatever cells you want, but I'll continue to recommend that people get closely matched cells, just as Jay Whiticare did. Also the extra cycle life of TS is projected, not documented as far as I know.

 

[JRP3]

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.

 

[JRP3]

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.

 

[JRP3]

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.

 

[JRP3]

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.

 

[JRP3]

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.

 

[JRP3]

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.

 

[JRP3]

Don't top balance your cells. Just buy them and charge them and go. You do need to watch them for a few cycles to be sure they all fall within a normal range. They should with no intervention. Don't discharge your new pack first. You need to charge it up first. NOT top balance. There will always be some variances but they should be very very very closely matched from the factory.

I never said you should top balance, or bottom balance, I was just using them as examples to clearly point out the differences of the effects in cell capacity and relative SOC.

I fully agree that cells should be well balanced and if your truly concerned then you need to contact the company and have them log every cell capacity and IR and SOC from the factory and to be sure that they all match. Expect to pay more because it will take some effort to IR and Capacity match a set of cells for you.

My point is it should be common practice to sort cells in that manner at the factory. CALB, and I suspect TS, already measure capacity and resistance of each cell as part of QC so it's a simple matter to group like cells together.

 

[JRP3]

No, the smaller cell will last the normal time and the others will just last longer. The higher one can't affect the lower on at all. The life of the low cell is the life of the group. It sounds like your saying that the cell with more capacity will cause the lower capacity cell to actually age faster than normal. If you set your pack up to operate within the factory specs then it will last as the factory states. Might even last longer. But the one with more capacity can't make that low cell actually age faster.

Pete

Never said the larger cells would do anything to the smaller cells, I said the differences will be exaggerated as time goes on. These differences will probably lead to an imbalanced pack, we just don't know the effect over time.

 

[JRP3]

Well it does cost money to group and measure for EACH cell. I'd expect if you wanted that you'd have to pay for that service. I would not expect any different. I think the manufacturing process is pretty darn close and that there should be some checking of batches but not always every single cell. That is very time consuming and can become very expensive to pay to have that level of perfection.

Every cell is already tested for capacity and resistance. It has to be in order for them to know if they have a functioning cell and to see if it falls within specs. As Jack says it's an automated process. Each cell has a serial number on it. The only added effort is to include a copy of the data sheet with the cells. CALB cells are only slightly more expensive than TS last I checked, which probably has more to do with their flatter discharge curve and better density than the data sheet that comes with them.

 

[JRP3]

As mentioned the latest shipments of CALB cells have come in under 1%.