Helping a friend get some lifepo4 -- is this a good deal?

[autumnbreeze27]

If you were buying new 1000ah cells, would you spend $1000 on used cells (cycled 20 times for a prototype project, age 4-5 years) or $1400 for new? The used cells come with a 1 year warranty, the new ones 3 years. The batteries were stored properly, the company suggests that the used ones should be good for 6-15 years depending on use.

They also have some 700ah cells for $700 vs $950 new. Same deal.

The batteries are in the USA already, and are from a reputable company and reputable source in China (they supervise the construction)

These aren't for me, but for a friend. We have a 400ah setup and are very happy with it.

[sailormed]

"Cycled 20 times". How do you know that this is true? Impossible to control this AFAIK.

[Jd1]

What SOC were they stored at over those 4-5 years ?
I would insist on a full cycle test of capacity which should give you a good idea what you are getting. Problem is, that will take many days of your time, assumes you have relevant equipment and of course also assumes that the seller trusts you with the cells without payment up front.
Personally, I would probably be more interested at half of new price (with a full cycle test)

I should add that it has been mentioned several times that larger cells are not good for boats because of physical issues with the internal supports. 400 AH seems to be optimal (based on what was mentioned here). I myself have 700 AH cells and they are doing fine but if I was to do it again I would put in 400 AH cells at a slight cost and size premium.

[autumnbreeze27]

This is a battery mfg company, so I'm assuming the batteries were stored properly. It's not from some guys garage sale.

Assuming they would test the capacity before shipping, is it worth 30% off? Realistically the batteries should be "like new".

Is there a better source for batteries in the USA? I talked to a guy who imported his from china, and said it wasn't worth the hassle and time and he would never do it again. These batteries are $1.36-$1.40/ah new, or $1/ah if he goes with the used ones.

[dlentz]

Originally Posted by autumnbreeze27

Assuming they would test the capacity before shipping, is it worth 30% off? Realistically the batteries should be "like new".

.

No.
I got these same cells for $400 or $425 almost four years ago. At that time they were only a year old with 20-25 cycles. 30% off doesn't seem very exciting to me, but maybe that's the market now? Absolutely no problems with the cells (700 ahr Winstons) though. Don't believe everything you read on the internet.

[offpist]

We have had winston 1000AH cells for 2 years and have crossed the atlantic twice. We love them. I would also expect about 50% disount on 5 year old cells. if that is tve best offer i would rather buy new ones. Btw i paid lesd than 1000 euro each pr cell new, but it was an special offer.

[hellosailor]

The seller says the batteries should be good for 6-15 years, but they will only warranty them for one year? Ergh...do the math.

They don't really trust their own product, either.

"I should add that it has been mentioned several times that larger cells are not good for boats because of physical issues with the internal supports. 400 AH seems to be optimal"
But I don't think any of the call makers actually goes on record as saying anything above 100AH size is suitable for use on boats, as of last year.

I know some forum members have lucked out (eventually) on "not quite new" cells and larger cells but can't help wonder why the makers can't get themselves established, and why "luck" has to be an issue at all after this many years.

[autumnbreeze27]

Originally Posted by hellosailor

The seller says the batteries should be good for 6-15 years, but they will only warranty them for one year? Ergh...do the math.

They don't really trust their own product, either.

"I should add that it has been mentioned several times that larger cells are not good for boats because of physical issues with the internal supports. 400 AH seems to be optimal"
But I don't think any of the call makers actually goes on record as saying anything above 100AH size is suitable for use on boats, as of last year.

I know some forum members have lucked out (eventually) on "not quite new" cells and larger cells but can't help wonder why the makers can't get themselves established, and why "luck" has to be an issue at all after this many years.

Do you really think the problem is trusting their product? Or maybe is it trusting the people not to abuse the batteries? I haven't seen much info on the larger cells being a problem, I have heard that the 400ah are usually pretty good. Every time I've asked an engineer in the industry about it they always claim to have hundreds/thousands of batteries in trucks without any problems.

I'm not seeing anything new and reputable for under $1.40/ah though... right?

[hellosailor]

Autumn- Let's say the problem IS the user. That's a given. But then, is there any reason why the "average" user gets a 3 year warranty, while the user who "knows" these are as good as new, can't be given THE SAME warranty? Is the real difference there the user? Or that the seller really can't be sure of those batteries?

You know, Igor sets up a battery bank, powers up a monster, gets his hands full for a year or two. Oh, darn, I forgot to mothball those batteries! And two years later, they get sold off.

Once upon a time, I was one of a small number of folks who got invited to comment on a proposed new piece of equipment from a manufacturer that we were all very familiar with, and had good relations with. They were going to bring out a piece of equipment under $20,000 [read: 19,999] when the nearest comparable thing on the market was more like $200,000. Earthshaking, did we all have any comment about it.

Well, yeah. I said I don't buy toasters with only a 90-day warranty on them. We (the folks in the business) all knew these machines needed a service contract, and we all knew you had to pay for it one way or another. So if that cost $3k, and the selling price had to be $23k to make that a one-year warranty? BFD, it was still a huge price offer. But the one-year said someone had confidence in it. (Or their service organization.)

Funny thing, that piece of equipment came on the market three months later. Priced at $22,995 with a one year warranty.(G)

I'd be really interested in lithium batteries. But after at least five years of "big interest" in them? The makers are still changing. The recommendations for charging and storage and even what sizes are suitable, keep on changing. And somehow, no proven competent businessmen have shown real interest in building a US warehouse and distribution system, aside from a couple of guys who buy the odd pallet for niche hobby users?

It just seems like a solid product, from a solid source, could and should have made a better foothold by now.

[snaptwo]

Ok, so these cells must be Winston/Thundersky. If they have been stored correctly 30 to 60 percent SOC in an appropriate storage temperature range and have been recharged correctly every few months they will be fine, and continue to provide good service. However they key is ensuring they have been properly stored and charged. Obvious physical indicators for these cells having been over discharged and then recharged is swelling - although this can be recoverable, it indicates an issue to be avoided. In addition after storage each cell will have a different voltage and capacity profile meaning that (as should be the case even with new cells) the BMS will need to be able to handle the cell balancing and be rated for this size cell. Any cells that are particularly out of step with the others again should be avoided as they create real issues in a series string. The typical life of a Winston/TS cell of this size in a light use application is well in excess of 1000 cycles to 80%, and degradation is pretty linear. If you want to buy them ask for a discharge curve for each cell from fully charged to cutoff voltage, and have that data looked at for voltage and capacity before you buy - that will show the gremlins pretty clearly, and if stored properly and with only 29 moderate cycles will show close to if not full capacity. Expect the vendor to charge you for this service.