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Discussion Starter #1
So, I am looking to replace my 44, 8 year old Thundersky 100aH cells in my Bug with an equivalent prismatic LiFePO4 cell. The TS are still useful, but I think it may be prudent to make a change before it gets too late. Plus I may use the TS cells as a "powerwall" setup. I am not interested in Leaf, Tesla, 18650 etc. Because I don't want to reconfigure anything, or buy new components to accommodate a different tell type or configuration.
I have an opportunity to purchase some VERY low use(less than 200 miles and under 30 cycles) Calb CA100 cells from a forum member here. He has been conducting capacity tests on them and thus far has determined they are around 100ish aH each. They are almost 5 years old, and have sat unused at no more than 90% charged for the majority of their life.
Questions;
1. How concerned should I be with their remaining life span of these used Calbs?
2. How long should I expect they will last from this point on?
3. What is a fair price for cells I this condition?
My 7+ year old ThunderSky have around 50,000 miles on them(the first 14,000 were pretty abused, the last 36K from me have been very gentle), and they could probably last me another 5-10k of easy driving. So I don't need to replace right away, but also don't want to pay for new ones if not needed yet.
Does anyone out there have a set of Calbs and can chime in one their experience, and how many miles/years they have on them?
 

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If you absolutely trust the PO's word they may have 80% cycle life left and half the calendar life.

I would not pay more than 25% new price myself, and even that only after doing my own random capacity testing.
 

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Discussion Starter #3
Thanks John...so that would be around $30 per cell. What is the expected calendar life of these cells if used properly? The seller is being very open about the cell testing by providing cellpro 6 screenshots with charge/discharge and resistance readings etc.
 

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I think I know which seller you're talking about, and if so, I wouldn't have any issues with his reputability.

What can you expect out of them?

Jehu Garcia recently did some tests on some calender old, but use-wise new cells. He determined that age had almost no factor in "aging" the cells if they were stored properly. This contradicts some often-repeated-but-I've-never-heard-verified statements about how lithiums begin to degrade from the moment they're manufacturered and it's just a matter of time. The cells weren't the same as yours, but, chemistry-wise that's what he determined.

1. How concerned should I be with their remaining life span of these used Calbs?
If he says they weren't badly used, or poorly stored, or heavily discharged frequently, and you trust him, I'd say you have almost no issue, they'll be fine. 80% or more. If he's even testing them for you, then you can rely on that.

2. How long should I expect they will last from this point on?
Time-wise, I think it plays a very small role. If they're relative unabused, should be pretty close to new.

3. What is a fair price for cells I this condition?
The problem with that question is that there isn't much of a market for these.

The buyer is lucky to have found someone who wants them at all, as people wanting to replace without changing their system would be pretty much the only people who'd buy them, and you (the buyer) are lucky to have found anyone who's selling them because pretty much only someone who had an aborted project would still have some. If the seller was trying to get rid of them, he might get pennies on the dollar. If you needed to buy something very specifically, and somewhat antiquated, you might end up having to pay nearly new price.

Any price you are happy to pay is fair. Any price he would happily sell them for is fair. As to where the price should fall between those extremes... that depends only on your negotiating ability.

Recent comparables and "how much would you have to pay/let them go for otherwise" would also be a good guide to go by, but, again, not much of a market at all, hard to gain knowledge about their price.
 

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Discussion Starter #5 (Edited)
Thanks Matt, solid advice. I saw the Jehu video you reference, slightly unscientific analysis of his cells with some motivation for selling purposes. However, he had some good points. As for the seller, yes he is who you think since I have seen where you had some posts on his for sale thread. He is definitely testing them because his screenshots are with the current dates, plus I have no reason to doubt him.
As for price, yeah, we tentatively agreed on a price, but I want to insure my outlay of funds are going to give me a pretty good return on investment vs buying new Calbs, so I am seeking anyone here who has experience with long term use or storage compared to capacity degradation.
There is a really good dissertation i found online with scientific capacity testing of cell degradation due to temperature and calendar capacity loss.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://uwspace.uwaterloo.ca/bitstream/handle/10012/12177/Catton_John.pdf%3Fsequence%3D3&ved=2ahUKEwj5p6Gf2p_cAhUGRKwKHeRbBYgQFjAEegQIBBAB&usg=AOvVaw3OUJjrq3GnnWwy52qjWw0g
 

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Thanks John...so that would be around $30 per cell. What is the expected calendar life of these cells if used properly? The seller is being very open about the cell testing by providing cellpro 6 screenshots with charge/discharge and resistance readings etc.
Well certainly longer than they've been on the market so far, if stored properly, low SoC and low temps.

Extrapolations from lab experiments won't match real life.

If they are used in an EV or other high-C rate application, irrelevant anyway.

As a House storage bank only used weekends I'd guess well over a decade?
 

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If you decide to replace your pack, I would be interested in 4-5 of your ThunderSky cells. I have a pack that's almost identical to yours. I have 3 cells that I abused enough that they are noticeably different than the others. I would like to replace them and get a couple of spares.

My car is at: www.evalbum.com/2778

Mike

So, I am looking to replace my 44, 8 year old Thundersky 100aH cells in my Bug with an equivalent prismatic LiFePO4 cell. The TS are still useful, but I think it may be prudent to make a change before it gets too late. Plus I may use the TS cells as a "powerwall" setup. I am not interested in Leaf, Tesla, 18650 etc. Because I don't want to reconfigure anything, or buy new components to accommodate a different tell type or configuration.
I have an opportunity to purchase some VERY low use(less than 200 miles and under 30 cycles) Calb CA100 cells from a forum member here. He has been conducting capacity tests on them and thus far has determined they are around 100ish aH each. They are almost 5 years old, and have sat unused at no more than 90% charged for the majority of their life.
Questions;
1. How concerned should I be with their remaining life span of these used Calbs?
2. How long should I expect they will last from this point on?
3. What is a fair price for cells I this condition?
My 7+ year old ThunderSky have around 50,000 miles on them(the first 14,000 were pretty abused, the last 36K from me have been very gentle), and they could probably last me another 5-10k of easy driving. So I don't need to replace right away, but also don't want to pay for new ones if not needed yet.
Does anyone out there have a set of Calbs and can chime in one their experience, and how many miles/years they have on them?
 

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Discussion Starter #8
Mike,

I plan on performing a capacity test on my TS cells after they are removed. That will take me a few weeks. I can get back with you afterwards. I may build a powerwall, so I will need to see how many cells I need to keep. I have 44 in my car and some extras as well.

Steve

PM me if I forget!
 
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