Discounted Cells That Have Been In Storage

[googdot]

What's the general consensus on cells that have been stored long-term?

I am looking at the LF280K cells, and can either choose newly manufactured ones or go for some that have been in storage for about 18 months (all cells are storage grade and not automotive grade)

The stored cells are 20% cheaper and not have not been touched since they were manufactured and shipped from China. Quick check of these cells show them around 270Ah or so. Maybe some concern of storage degradation as well?

Are they worth the discount?

 

[sunshine_eggo]

What's the general consensus on cells that have been stored long-term?

I am looking at the LF280K cells, and can either choose newly manufactured ones or go for some that have been in storage for about 18 months (all cells are storage grade and not automotive grade)

The stored cells are 20% cheaper and not have not been touched since they were manufactured and shipped from China. Quick check of these cells show them around 270Ah or so...I'm guessing there is likely some storage degradation occurring on them.

How do you do a quick check of them to determine 270Ah? Even with a 40A tester, that's > 4 hours of testing on discharge alone.

I would expect 18 month properly stored cells to be no more than 1-2% lower than fresh. Properly means stored at 30-70% SoC in a climate controlled environment at or below 25°C.

if 1-2% degradation gives a 20% discount, I'd consider it if the seller offers the same warranty and guarantees a minimum capacity.

 

[googdot]

How do you do a quick check of them to determine 270Ah? Even with a 40A tester, that's > 4 hours of testing on discharge alone.

I would expect 18 month properly stored cells to be no more than 1-2% lower than fresh. Properly means stored at 30-70% SoC in a climate controlled environment at or below 25°C.

if 1-2% degradation gives a 20% discount, I'd consider it if the seller offers the same warranty and guarantees a minimum capacity.

I'm only going by what the seller has told me as I can't view the cells myself.

He won't do a full capacity test or top balance them or anything - just wants them gone for that price. He did say he will measure IR to try and get a set of 8 for me that are at least close.

 

[sunshine_eggo]

I'm only going by what the seller has told me as I can't view the cells myself.

He won't do a full capacity test or top balance them or anything - just wants them gone for that price. He did say he will measure IR to try and get a set of 8 for me that are at least close.

He'd have to guarantee 265Ah before I'd bite.

 

[Alkaline]

What's the general consensus on cells that have been stored long-term?

I am looking at the LF280K cells, and can either choose newly manufactured ones or go for some that have been in storage for about 18 months (all cells are storage grade and not automotive grade)

The stored cells are 20% cheaper and not have not been touched since they were manufactured and shipped from China. Quick check of these cells show them around 270Ah or so. Maybe some concern of storage degradation as well?

Are they worth the discount?

I'm only going by what the seller has told me as I can't view the cells myself.

He won't do a full capacity test or top balance them or anything - just wants them gone for that price. He did say he will measure IR to try and get a set of 8 for me that are at least close.

If the seller is saying 270 you can expect 250.

Avoid.

 

[LakeHouse]

I'm only going by what the seller has told me as I can't view the cells myself.

He won't do a full capacity test or top balance them or anything - just wants them gone for that price. He did say he will measure IR to try and get a set of 8 for me that are at least close.

IR tells you almost nothing. Or maybe exactly nothing.
I would be far less worried about the 18 month storage than the actual quality and capacity of the cells. 20% discount for someone else’s rejects that he won’t test and you can’t? I’d at least be suspicious.

 

[Rednecktek]

Would this be for a live system or a play system? For 20% if it were a play system that would be good for me. A good top balance and quality BMS can go a long way and even if you only get 250 out of them, that's still cheaper than new 250's.

Just my thoughts. LFP is supposed to have a great lifespan after all and if they've just been sitting on a shelf that's no wear on the cycle counts.

 

[Steve_S]

OK, I have to clear a few things up here.
IF the cells were simply STORED after being received and they did not discharge below 2.500V then it is most unlike that there is ANY loss whatsoever. Assuming the cells were tested to 280AH they should still be capable.
If the cells were static even heat / cold would not have much affect on them.
They will HAVE TO BE TOP BALANCED ! All LFP must to Top Charged & to 3.650 and then Balanced with the other cells. This reactivates the electrolyte and is recommended by every manufacturer.
- I would wager that the current Cell Voltage is likely around 3.000-3.100 volts per cell. (that would be quite normal even down to 2.900)

LFP will ONLY DEGRADE if ABUSED !
Abuse means operated outside of specs or if improperly stored. Neither is teh case in this instance.

IF it was me, I would buy them and call them 275AH and be happy with that.
I would suggest STRONGLY that you buy a Battery Tester like the YR1035+ and test the IR of the cells at the following Cell voltage points.
2.800, [ 3.000, 3.100, 3.200, 3.300, 3.400 ], 3.450, 3.500.
The values between the [ ] brackets is the Working Voltage Range which is the flat part of the voltage curve that delivers your rated Net AH.
The IR at the different voltage points indicate how much difference between the cells, try to match them up as close as possible.

Do be aware that LFP like ALL Battery chemistries has TWO Voltage Ranges.
The Allowable Range is from 2.500->3.650. This is the voltage range where there is no Harm/Damage done to the cells. The GROSS Capacity is measured from this and is typically 5-7% over the cell rating. IE a 280AH battery gross would be anywhere from 287-292AH. (quite typical)
The Working Range is from 3.000-3.400. This is the Flat Curve that delivers the NET AH Label Rating of the cells. Most people will use from 2.800 to 3.450 to get the most while remaining safely conservative.

Note that Non-Grade A Factory Matched & Batched cells (premium) can be pushed to the edges but B-Cells cannot.
In "GENERAL" LFP cells will deviate within a pack after 3.425 Volts and below 2.750 which is most common.
When you Fully Charge your battery packs they will settle down as the charge stops, this is quite normal as well.

For Info: YR1035+ on Ebay

YR1035+ Lithium Battery Internal Resistance Tester Meter Range 0-100V 0-200Ω | eBay

Find many great new & used options and get the best deals for YR1035+ Lithium Battery Internal Resistance Tester Meter Range 0-100V 0-200Ω at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[googdot]

He'd have to guarantee 265Ah before I'd bite.

Thanks very much - it's my first lifepo4 bank as we've been on AGM batteries the last eight years, and you've answered a few of my questions now so much appreciate the help and knowledge.

 

[googdot]

Would this be for a live system or a play system? For 20% if it were a play system that would be good for me. A good top balance and quality BMS can go a long way and even if you only get 250 out of them, that's still cheaper than new 250's.

Just my thoughts. LFP is supposed to have a great lifespan after all and if they've just been sitting on a shelf that's no wear on the cycle counts.

It would be for a live system - have been on AGMs the last eight years and now making the switch over.

I can get the LF304 for a decent price from a different seller (about 10% more in cost than these stored units), so am looking into that as well.

 

[googdot]

OK, I have to clear a few things up here.
IF the cells were simply STORED after being received and they did not discharge below 2.500V then it is most unlike that there is ANY loss whatsoever. Assuming the cells were tested to 280AH they should still be capable.
If the cells were static even heat / cold would not have much affect on them.
They will HAVE TO BE TOP BALANCED ! All LFP must to Top Charged & to 3.650 and then Balanced with the other cells. This reactivates the electrolyte and is recommended by every manufacturer.
- I would wager that the current Cell Voltage is likely around 3.000-3.100 volts per cell. (that would be quite normal even down to 2.900)

LFP will ONLY DEGRADE if ABUSED !
Abuse means operated outside of specs or if improperly stored. Neither is teh case in this instance.

IF it was me, I would buy them and call them 275AH and be happy with that.
I would suggest STRONGLY that you buy a Battery Tester like the YR1035+ and test the IR of the cells at the following Cell voltage points.
2.800, [ 3.000, 3.100, 3.200, 3.300, 3.400 ], 3.450, 3.500.
The values between the [ ] brackets is the Working Voltage Range which is the flat part of the voltage curve that delivers your rated Net AH.
The IR at the different voltage points indicate how much difference between the cells, try to match them up as close as possible.

Do be aware that LFP like ALL Battery chemistries has TWO Voltage Ranges.
The Allowable Range is from 2.500->3.650. This is the voltage range where there is no Harm/Damage done to the cells. The GROSS Capacity is measured from this and is typically 5-7% over the cell rating. IE a 280AH battery gross would be anywhere from 287-292AH. (quite typical)
The Working Range is from 3.000-3.400. This is the Flat Curve that delivers the NET AH Label Rating of the cells. Most people will use from 2.800 to 3.450 to get the most while remaining safely conservative.

Note that Non-Grade A Factory Matched & Batched cells (premium) can be pushed to the edges but B-Cells cannot.
In "GENERAL" LFP cells will deviate within a pack after 3.425 Volts and below 2.750 which is most common.
When you Fully Charge your battery packs they will settle down as the charge stops, this is quite normal as well.

For Info: YR1035+ on Ebay

YR1035+ Lithium Battery Internal Resistance Tester Meter Range 0-100V 0-200Ω | eBay

Find many great new & used options and get the best deals for YR1035+ Lithium Battery Internal Resistance Tester Meter Range 0-100V 0-200Ω at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Thanks for the reply and all the info.

The cells were simply stored and have been sitting there untouched for the 18 months. The seller is willing to do the IR test and match them as close as possible. Of course I would then top balance them myself if I end up going with them.

I can get the LF304 for a decent price from a different seller (about 10% more in cost than these stored units), so am looking into that option and trying to decide what's best.

 

[DIYrich]

Think of it as buying used off eBay. I would want a good discount to make it worth the hassle.

 

[houseofancients]

It would be for a live system - have been on AGMs the last eight years and now making the switch over.

I can get the LF304 for a decent price from a different seller (about 10% more in cost than these stored units), so am looking into that as well.

i would go for the 304's.
the 280k series in my mind is a tainted one, always comes below ah's and in very many case relasered because of popularity.

if you have the chance of 304, you get 20ah more ( these usually test 313-320 the first cycles) , with less chance of other none sense

 

[HRTKD]

For a first system, I would go for the new cells. I wouldn't want someone new to LiFePO4 to have to struggle with questionable cells. You wouldn't know if a problem is with the cells or with something you did.