Fullriver LiFePO4 32700 (box of sixty)

LewTwo

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Daddy taught me that if a deal sounded too good to be true then it usual was not true. However I keep see these Lithium Iron Phosphate Rechargeable 32650 advertised on ebay and Amazon ..."WOW, That really seems like a good deal".
  • Manufacturer: Guangzhou Fullriver Battery New Technology Co., Ltd.
    Model: 32700Fe
    Nominal Voltage: 3.2 - 3.3 V
    Nominal Capacity: 5400 mAh
    Energy density: 125 wh/kg; 300 wh/l
    Charging current: 3.3 A Max.
    Discharging current: 9.9A continuous
    Operating Temperature:
    Charging: 0° to 45°C
    Discharging: -20° to 60°C
    Cycle Performance:
    >2000 (80% of initial capacity at 0.2C rate, IEC Standard)
    2 times more than NiMH and 10 times more than SLA
    Dimensions (DxH): 32.3mm (1.27") x 72.0 mm (2.83")

Box of 60 for $89.99 with $10.19 Shipping
https://www.ebay.com/itm/351913374341

Same thing on Amazon (bit more for shipping)
https://www.amazon.com/dp/B01M9AD7NN

Now the way I figure it, that box should provide a 15Sx4P battery with nominal 48Volts and 21.6 Ahrs.
Too Good to be true for that price. Of course that does not include a BMS or charger or putting it all together.
What am I missing?
 
The following applies to any cell you see for sale anywhere.

Unless they have a discharge curve graph posted (for at least typical C-rate and max C-rate, preferably for a few), you won't know what kind of voltage sag you'll get at their "continuous" rate. That will affect how much power you actually get from a pack, and/or how many parallel cells you'll need in each group to keep sag to a minimum at your needed currents.

You also won't know how much capacity you actually get out of them at the various rates (because it will be less at higher currents, but how much less is different for each cell design).

As a note, their 9.9A continuous current is not even 2C, with 5.4Ah cells.

And without a cycle life discharge curve graph, you won't know how many cycles you'll actually get at a useful C-rate (their 2000 cycle listing is at only 0.2C, and unless you have a lot of parallel cells you're probably going to pull significantly more than that).


Also--unless you're buying from the factory (and maybe even then), you don't know if what you're getting are the seconds, that don't actually meet the specs provided, or even the DOA cells someone else returned, or another company scrapped for recycling because they didn't work right, etc.


So you might be getting a really good deal...but in many (most?) cases, if the deal looks good, it's probably not.
 
H'mmmmmmmmmm .... more research then.

This is the link to the specs at the manufacturer's web site:
http://www.fe123battery.com/english/pro.asp?b_class=12&id=95
Part Number: 32700Fe5400
That shows a max discharge rate of "2C"
Unfortunately the link to the detail spec sheet for this product is broken.
I will email them about the broken link (for whatever good that will do).

I did find a link (that worked) for their 32700Fe5000HT ( HT = High Temperature)
http://www.fe123battery.com/editor/UploadFile/201712416200231.pdf
 
None of this might make any difference, but:

I looked at a couple of cell spec pdf's there, and neither show any curves at multiple C-rates, just at 0.5c, which is probably not a typical usage rate for ebike stuff. (even low power bikes are also usually using small-capacity packs, and so the c-rate the systems impose on the pack is proportionally higher, so even if you don't have a high power bike it can be harder on cells than some of these are graphed for).

Without testing to see, I couldn't say what the voltage sag might be at teh higher rate, but since the rate they chart at is only 1/4 the max continuous rate, I suspect the sag at the higher rate would be significant.

I don't know what the lifespan difference would be at the higher rate, either. They spec the 2000 cycles at 0.2c, but they graphed 0.5c at 25celsius giving 1100 cycles. Extrapolation: If it cuts the lifespan in half to just a bit more than double the discharge rate, then to go another four times the discharge rate would probably cut the lifespan by four, giving only 250 cycles. That's assuming they're at the full 2C discharge the entire time, which wouldn't likely be the case, of course. :)


Anyway, it's all a guessing game without actual numbers and graphs from them, specific to the cell in question.
 
hello all,

these seems to be the specs for it

https://www.fe123battery.com/en/product_show.php?id=19

not powerfull for ebikes, but for my application which is solar , its great.

now trying to set up my solar charge controller for the right parameters....
 
LewTwo said:
Daddy taught me that if a deal sounded too good to be true then it usual was not true. However I keep see these Lithium Iron Phosphate Rechargeable 32650 advertised on ebay and Amazon ..."WOW, That really seems like a good deal".
  • Manufacturer: Guangzhou Fullriver Battery New Technology Co., Ltd.
    [...]
    Now the way I figure it, that box should provide a 15Sx4P battery with nominal 48Volts and 21.6 Ahrs.
    Too Good to be true for that price. Of course that does not include a BMS or charger or putting it all together.
    What am I missing?


  • They might be old. The boxes are probably date coded, and an honest seller will tell you what the date is.

    A friend of mine bought over 12,000 similar cells (Fullriver 3300 mAh) for $1000 plus tax. They had been sitting new in the box for at least seven years without climate control. Some of them on the outsides of the stack were at zero volts. Others were holding at over 3 volts. I helped him sort cells by residual voltage and make them into packs as large as 16S 20P, and as small as 4S 4P.

    In his case, the cells can only be depended upon for about half their rated capacity. At $0.08 per cell, that's still a pretty good deal. In his application, extra weight and size isn't a major drawback.

    If the cells you're looking at are recently made and they deliver their rated energy, then they are a very good bargain, just under $100 per kWh. I sometimes find offers in that range, but almost always salvaged cells.
 
LewTwo said:
LOL .... at this point the thread may be older than the batteries.

D'oh!
 
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