18650 Cell choice: Max Constant Current 1/12th of Capacity?

[Gazza]

Hello,

I am planning to assemble a Solar Battery from New 18650 cells.
Panasonic, Sonyo or LG seem to be the leading, verifiable brands.

When I ask for quotes I am bombarded with all the newest High Discharge Cells.

Unlike the Majority of requirements for Cars, Bikes and lights,
my requirement is for a Max Constant Current <= 1/12th of the Cell Capacity.

So these are some Lower Discharge types I have stumbled upon,
or followed up after suggestion.


LG INR18650F1L(Rated 3350mAh) (1.5C Max 4.875A)

*PANAS0NIC NCR18650BE (Rated 3200mAh) (Typical 3180mAh) (1.1C Max 3.63A)
*PANAS0NIC NCR18650G(Rated 3400mAh) (Typical 3550mAh) (1.3C Max 4.87A)
*PANAS0NIC NCR18650 (Rated 2700mAh) (Typical 2900mAh) (2C Max 5.8A)
*PANAS0NIC NCR18650D (Rated 2700mAh) (Typical 2550mAh) (2C Max 5.1A)
*PANAS0NIC NCR18650F (Rated 2700mAh) (Typical 2900mAh) (2C Max 5.8A)
*PANAS0NIC NCR18650A (Rated 2900mAh) (Typical 3070mAh) (2C Max 6.14A)
*PANAS0NIC NCR18650B (Rated 3200mAh) (Typical 3350mAh) (2C Max 6.7A)
*PANAS0NIC NCR18650BF (Rated 3200mAh) (Typical 3350mAh) (2C Max 6.7A)
*PANAS0NIC NCR18650E (Rated 2100mAh) (Typical 2250mAh) (3C Max 6.75A)
*PANAS0NIC NCR18650BL . . . . . . . . . . . . . . (Typical 3350mAh) (2C Max 7A)

Looking for Common Cells that might be cheap for +500 and +1000 pieces.
Any suggestions for other Commonly Available, High Quality Cells that might be Suitable for Lower Continuous Current?

Thanks,
Gazza

 

[wesnewell]

Don't know why you'd want to use 18650's for this but you can find specs for many here.
http://lygte-info.dk/review/batteries2012/Common18650comparator.php

 

[tomjasz]

If you use Facebook here a pretty good power wall group.

 

[Gazza]

Don't know why you'd want to use 18650's for this but you can find specs for many here.
http://lygte-info.dk/review/batteries2012/Common18650comparator.php

Hi Wesnewell,

Some options used in US have not got the Market Saturation Pricing in AU.
I am very open to any ideas, what did you have in mind and why?

Thanks,
Gazza

 

[Sunder]

I am also confused as why you woulf use 18650s for a stationary application. 18650s are well protect cells with a good energy density for mobile applications where cost is secondary to other concerns.

Depending on your expected longevity, climate and willingness to spend money, I'd consider either large format LiFePo4, or under-rated LiPo.

A LiPo pack kept under 25*C and used between 3.5v and 3.9v only, can have a cycle and shelf life comparable to LiFePo4, while still being smaller, lighter and better discharge rates.

 

[Gazza]

I am also confused as why you woulf use 18650s for a stationary application. 18650s are well protect cells with a good energy density for mobile applications where cost is secondary to other concerns.

Depending on your expected longevity, climate and willingness to spend money, I'd consider either large format LiFePo4, or under-rated LiPo.

A LiPo pack kept under 25*C and used between 3.5v and 3.9v only, can have a cycle and shelf life comparable to LiFePo4, while still being smaller, lighter and better discharge rates.

This is interesting, what part numbers would you look at for 25 to 40C?
Maximum Discharge <= 1/12th Battery Storage Capacity!
Maximum Bank voltage is 60, minimum can be as low as 40v.

Keeping a LiPo pack under 25C might not be possible, would it still be an option at <=30C?

The Cost of 18650 and its expected longevity is the benchmark to compare LiFePo4, or under-rated LiPo.
The real price evaluation only includes longevity divided by cost.
If we just look at cheap, I would use Second hand Lead Acid.

Keen to hear what Battery type and part number you would use for this application.

Thanks,
Gazza

 

[wesnewell]

What size battery pack are you planing on building? Voltage? AH?. And what will the max amperage draw from it? You confuse me with wanting to use 1C 18650 and 30C lipo. At a 1C max discharge, and not over charging or over discharging, 10C lipo should last at least 5-10 years or more. Although 2C rated lifepo4 would make a safer solution, and might last a littler longer. But it may cost more too.

 

[Gazza]

What size battery pack are you planing on building? Voltage? AH?. And what will the max amperage draw from it? You confuse me with wanting to use 1C 18650 and 30C lipo. At a 1C max discharge, and not over charging or over discharging, 10C lipo should last at least 5-10 years or more. Although 2C rated lifepo4 would make a safer solution, and might last a littler longer. But it may cost more too.

Hi Wesnewell,

It will take me a while to look into your info.

50 and 100Ah Bank options.
48v Nominal, 60 Max, minimum could be down to 40v.
Max Discharge Current < or = 1/12th Bank Capacity.
Charge rate of half Bank Capacity is sufficient.
Operating Temperature: 25 to 40C.

Note: This is off-grid, theoretically the system could control the Temperature where batteries are stored but the 40C covers worse case conditions with no cooling.

I will be honest and tell you I know nothing about lifepo4 or LiPo, it is very helpful to get kick in the right direction, saves a lot of internet bandwidth and Google searching.

Cheers,
Gazza

 

[Sunder]

Try 16 of these:

https://www.aliexpress.com/item/Bra...arge-for-electric-vehicle-EV/32677195432.html

They are very tolerant of both high and low temps, and since you only need 16 of them, you're not going to have issues with bad welds or solders, and if one cell goes bad, you can remove and replace it easily, without having to cut a 500+ cell battery apart to remove it.

Edit: I selected LiFePo4 as the best options due to the 40*C heat. If it's only a couple days a year, it might not be too bad, but even a month of 40+ degree days will shorten the life of LiPo.

If LiPo is desired, you can use 6 x 2 of these to get a 44v @ 96Ah battery:

https://hobbyking.com/en_us/multistar-high-capacity-6s-16000mah-multi-rotor-lipo-pack.html

That's about half the price of the LiFePo4 battery.

 

[Gazza]

Try 16 of these:

3-2v-lifepo4-100ah-high-capacity-power-cell-100A-3c-discharge-for-electric-vehicle-EV/

They are very tolerant of both high and low temps, and since you only need 16 of them, you're not going to have issues with bad welds or solders, and if one cell goes bad, you can remove and replace it easily, without having to cut a 500+ cell battery apart to remove it.

Edit: I selected LiFePo4 as the best options due to the 40*C heat. If it's only a couple days a year, it might not be too bad, but even a month of 40+ degree days will shorten the life of LiPo.

If LiPo is desired, you can use 6 x 2 of these to get a 44v @ 96Ah battery:

high-capacity-6s-16000mah-multi-rotor-lipo-pack

That's about half the price of the LiFePo4 battery.

I started with a plan using Panasonic NCR18650BE, loosely based on the findings for Panasonic NCR18650BE in the linked paper:
Increasing the cycle life of lithium ion cells by partial state of charge cycling
https://www.researchgate.net/public..._ion_cells_by_partial_state_of_charge_cycling

The Cells could easily be removed from bank individually with intended design.

Panasonic NCR18650BE (Rated 3200mAh) (Typical 3180mAh) (1.1C Max 3.63A)
Nominal 3.6v
Maximum 4.2

50Ah Bank
50A/2.15Ah Cell = 24 Cells
16 Cells in Series x 24 Parallel = 384 Cells in Total.
25A Charge rate.

Cells at 60% state of charge
V max 3.76
V min 2.50
60% SOC = 2.15Ah (Approximated)

Bank Voltage Range 40-60V
Max Bank Voltage: 60v/3.75v each =16 Cells
Min Bank Voltage: 40v/2.50v each =16 Cells

--------------

Using a lower maximum cell voltage means less then the cells rated current for longer cycle life.
The Electronics load has a 60v maximum.
At 48v the system operates at %97 efficiency and reduces exponentially for lower voltages.

The 40 to 60v operating voltage allows a large enough drop in voltage envelope whilst maintaining the required capacity.
In a perfect world the total capacity would be held between 48 and 60v to optimize efficiency but using a higher Battery voltage comes at reduced life cycle.

Thanks for the links, it gives me an idea of what is available.
I think these types of packs are going to be to expensive to get the required specs.

We get a Maximum temperature of 47 Degree C, the storage area for Batteries is insulated.
When it nudges towards 47C outside, the bank area is pushing towards 40C but would always remain just bellow.

Actual Bank area Temps
The minimum Temp is 25, the Yearly Mean Temp would be about 30C.
35C Daily temperatures for a couple of Months, a few weeks with daily peaks of 37C.

 

[Sunder]

Not 100% sure if I'm reading you right. But if you want 60v + undercharge cells from your battery, you can get those 6S packs, split some in half, and join them so you get 15S packs.

Then charge them to 4.0v per cell instead of 4.2v per cell. You should have about 85% of rated capacity for 4x extra life.

4v x 15 = 60v Max voltage
3.5 x 15 = 52.5 Recommended min voltage (They can go a little lower, but there's not much there, and they tend to get easily unbalanced under there)

 

[Gazza]

Not 100% sure if I'm reading you right. But if you want 60v + undercharge cells from your battery, you can get those 6S packs, split some in half, and join them so you get 15S packs.

Then charge them to 4.0v per cell instead of 4.2v per cell. You should have about 85% of rated capacity for 4x extra life.

4v x 15 = 60v Max voltage
3.5 x 15 = 52.5 Recommended min voltage (They can go a little lower, but there's not much there, and they tend to get easily unbalanced under there)

So 6S means x6 4.2v LiPo cells in Series? (Paralleled for Current)

This would give 25.2v max, 22.2v Nominal per Pack?
22.2v divided by 6 cells is 3.7v Nominal per Cell.
So you know these packs can be easily dissembled or just suggestion?
-----------------
-----------------

6S 6S 3S for 15S

15x 4 = 60
15x 3.7v = 55.5

100,000mAh / 16,000 = 6.25 packs.
6 parallel x 2.5 series = 15 Packs.
This sound right, or have I got something wrong?

15 Packs at $80 each = $1200

What Cells do they put in these packs?
Lot of questions, but an important one would be the thermal degrading for life cycle!
-----------------
-----------------

Out of interest, a Search for Multistar High Capacity 6S 16000mAh Cell candidates:

GEB7467140 3.7V 8000mAh rechargeable lithium polymer primatic
$3.26 x500 Pieces.
Another supplier
$6.52 x500 Pieces.

11.1V 8000mAh lipo battery pack flat lithium polymer battery 3.7v
$13.05 per pack / 3 = $4.35
Only 1 or 10 pack minimum depending on supplier.

So 180 Cells is $783 Shipping not included.
By the time Shipping is included the price of 3 Cell packs or 12 Cell Multistar might be similar, depends on what price breaks they give?

I wonder how equal Cell quality is among suppliers.
Anybody looked into the best Brand individual Cells?

 

[okashira]

Tesla Cells or Modules.

 

[Sunder]

So you know these packs can be easily dissembled or just suggestion?

Sorry for brevity if reply, answering from phone.

I recently pulled a lot of these apart to make a 36S (150v) motorcycle battery. The individual cells are not stuck together, so very easy to pull apart without damaging the cells. They also use standard 60/40 solder, instead of high temp silver alloy solder so again very easy to rebuild. I didn't need any flux or spot welding to get the packs together.

To be honest, had I seen cells as cheap as you listed, I would have had a look at those instead.can you provide a link?

I've had some shockers in loose cells and unbranded packs in the early days, so tend to stick with well known brands now, but for such a price difference, would have been willing to try a sample. I have some pretty good test equipment at home, including internal resistance meters and decent loads with watt meters.

 

[999zip999]

E Z bolt together lifepo4. E Z to monitor long life. Maybe used leaf modules.

 

[Gazza]

To be honest, had I seen cells as cheap as you listed, I would have had a look at those instead.can you provide a link?

I've had some shockers in loose cells and unbranded packs in the early days, so tend to stick with well known brands now, but for such a price difference, would have been willing to try a sample. I have some pretty good test equipment at home, including internal resistance meters and decent loads with watt meters.

Sounds good, lets make it happen.
Happy to help with searching and research over the longer term.

We also need to find people with experience of using some of these brands.
------------------

E Z bolt together lifepo4. E Z to monitor long life. Maybe used leaf modules.

Hi Zip,
I am in Australia and had to search the Term "leaf modules" but guessed it must of been Auto with borrowed analogy.
Unfortunately, our local Market is pretty limited outside AGM.
What I can access and works out the most cost effective is on the table.

Battery Packs that are very competitively priced must generally be assembled with competitively priced cells!
My knowledge is not good having only just started down this road, but presumably others here have already used some Brand cells available on Alibaba.
It might be just a matter of recognizing the cell in a picture on Alibaba.

Those in the US have a few more options, where Alibaba could be the answer for some Aussies.

 

[Gazza]

ALIBABA
https://www.alibaba.com/

Once I know there is a product with a specific ratting or voltage it can be included to narrow down Search Term and find it.
Like: "3.7V 8000mAh lithium"
Or: "11.1V 8000mAh lithium"

Finds: "GEB7467140 3.7V 8000mAh rechargeable lithium"
And: "11.1V 8000mAh lipo battery pack flat" (Eventually!).

Left side of Alibaba page, Example: choose 3v, filters to show 3.2v Cells.
The Alibaba Search Engine has a letter limit, just remove the meaningless words until it fits!

I start by look at the Maximum Price which should be for the Minimum number of Pieces shown.
If this price is good you can look at the other price breaks or contact seller.
-----------------------

I am looking at these products to find the most cost effective solution for application.

LiPo:
12V 100Ah lithium iron phosphate
3.2V 100Ah lithium iron phosphate
GEB7467140 Lipo battery 8000mah
Lithium ion polymer battery 3.7V 8000mah lipo

LiFePo4:
LiFePo4 3.2V 100AH battery
LiFePo4 12V 100AH battery (A Mine Field?)
LiFePO4 A123
LiFePo4 26650 Etc. .. .

Using Abbreviated Chem Name in front of number can be helpful:
EG: ICR26650
ICR = LiCo02
IMR = LiMn
IFR = LiFePO4

The challenge is finding someone with a bit of knowledge to sort out higher quality products or raise red flags.
-----------------

The other Suggestion was: 80x 26650 LiFePo4 batteries with 5000mAh US $119,99 - AUD $156.56
http://www.ebay.de/itm/351947933933?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Unfortunately this Product is in Leander, Texas, United States,
doesn’t ship to Australia. (Shipping from US is not viable in any case!)

Tenergy LiFePO4 22650 are not available through Alibaba!

There are Many other LiFePO4 32650 on Alibaba, the question for me is which manufacture has quality cells.
In order to make up 48v 100A!

I have made an assumption that 32650 LifePO4 would be the most cost effective format, but have not checked it out yet.
What can folks tell me, any ideas on brands and size formats, what to look for or at?

Thanks,
Gazza

 

[Sunder]

I am in Australia and had to search the Term "leaf modules" but guessed it must of been Auto with borrowed analogy.

Leaf Modules = batteries out of the Nissan Leaf. This annoys me so much, because Leaf modules are virtually unavailable here, except for the few that someone imports in from the US who then take a fairly hefty markup on it (Fair enough, considering the cost and risk of shipping lithium).

When I was building my motorcycle battery, the guys in the US were all like "Stop wasting your time and money, get a Leaf Pack for $2k, use half the modules, and you can sell the rest on eBay". Great. Except that in Australia, each MODULE was worth about $250. That would have made the whole pack worth more than $5k locally.

A few notes on your other post:

Lithium Iron Phosphate is LiFePo4. Li = Lithium, Fe = Ferrum (Iron), PO4 = phosphorus + 4 x oxygen = phosphate. You've got it under the LiPo category.

Just remember that as you look at different chemistries, any lithium chemistry that has cobalt in it, will degrade rapidly under hot weather. So 18650s, 26650s, 32650s, are all usually filled with a type of Lithium Ion like NMC and NCA.

As far as I know, Lithium Iron Phosphate and Lithium Titante are the only two who don't contain Cobalt, and therefore both have extremely long lives, irrespective of temperature. Both, as you have noticed, do cost a lot more than anything with Cobalt in it.

Thanks for the tips on Alibaba - explains why I didn't find those prices. I've found Alibaba prices to be "bait and switch". They advertise a low price, but when you email them to "get the latest price". it always goes up a fair bit. That's not adding freight and customs. That's the factory gate price seems to go up a fair bit before you add quite large hikes for freight and customs. I do use Aliexpress though, because it's a "buy it now" prices, and they are much closer to eBay prices, but at least they're real.

 

[Gazza]

Thanks for the tips on Alibaba - explains why I didn't find those prices. I've found Alibaba prices to be "bait and switch". They advertise a low price, but when you email them to "get the latest price". it always goes up a fair bit. That's not adding freight and customs. That's the factory gate price seems to go up a fair bit before you add quite large hikes for freight and customs. I do use Aliexpress though, because it's a "buy it now" prices, and they are much closer to eBay prices, but at least they're real.

Alibaba
The Lowest price is for Highest Number of Unit Pieces.
Maximum Price equals the Minimum Unit Pieces Order.
If a sellers numbers don't make sense, skip them.

Unit numbers per day a company can provide, trade and response stats are all indicators.

I have received 30 quotes from different sellers that fall within there stated price breaks.
Often the same Supplier is competitive across a range of Battery types.

lifepo4
I am looking for lifepo4 to make up 48v 100ah high capacity.
One Battery is putting your eggs in one basket.
1000 Cells might be some work to assemble, but I am up for it.

Has anybody had experience or done review on Products you find on Aliexpres or Ebay?

Like your linked: Large 3.2v lifepo4 100ah high capacity power cell 100A 3c discharge for electric vehicle EV pack diy storage solar system etc
https://www.aliexpress.com/item/Bra...arge-for-electric-vehicle-EV/32677195432.html
Winston WB-LYP100AHA-B http://winston-battery.ru/products/cells/wb-lyp100aha-b
Has anyone used this particular 3.2v lifepo4 100ah?

Any links to lifepo4 batteries that people have had good experience, all we need is a picture and brand name to look into higher number price breaks.
That is my request if anybody can help me?

-----------------------

Regarding your interest in LiPo, have we got some good close up pictures of the Multistar Cells?

Cheers,
Gazza

 

[Sunder]

With Alibaba, I was talking about getting quotes $55-65USD for a single LTO cell, then emailing them for the latest price for them to say that they were $110+ freight. So I'm aware they put very high volume pricing as their lowest price there, but by the same token, I would expect them to put their highest price as the MOQ. The true range was $55-$110, not $55-65.

Winston, CALB, Thundersky, these are all well known and trusted brands for that style of hard-case LiFePo4. I wouldn't say you couldn't go wrong with them (There are counterfeits out there after all), but they have been used a fair bit around here, including by me (Thundersky), and I'm quite happy with them.

 

[Gazza]

With Alibaba, I was talking about getting quotes $55-65USD for a single LTO cell, then emailing them for the latest price for them to say that they were $110+ freight. So I'm aware they put very high volume pricing as their lowest price there, but by the same token, I would expect them to put their highest price as the MOQ. The true range was $55-$110, not $55-65.

Winston, CALB, Thundersky, these are all well known and trusted brands for that style of hard-case LiFePo4. I wouldn't say you couldn't go wrong with them (There are counterfeits out there after all), but they have been used a fair bit around here, including by me (Thundersky), and I'm quite happy with them.

Yes, there is a lot of deception in the way sellers manipulate.
I am looking at starting a Business which would use 48v 100A modules.
In the past I have used Alibaba to try and purchase samples and had similar results.

I have got good quotes for +500 or +1000 Pieces, or small orders over $1000 AUD,
whether this translates to happy customer is scary in anybodies language, but I am having a go!

Just looking at GBS.
Not looked at Thundersky. I am confused after searching this and finding Winston, are they one of the same?
https://forums.energymatters.com.au/wind-solar-misc/topic5693-20.html Do I need a large bottle of Rum to understand this Thundersky/Winston turn CALB color thing??

Thanks for suggestion,
Cheers

 

[999zip999]

I'm using A123 20ah. Love the large format. 983 cycles . Heavy for a bike great for solar. They are very expensive now. But love large ah cell and lifepo4 being long life. Just find one double the c-rate you need.

 

[Sunder]

You've got me thinking again. This is an LTO battery:
https://www.alibaba.com/product-detail/Fast-charging-deep-cycle-Lithium-titiant_60609356807.html?spm=a2700.7724838.0.0.0ZO6nw

It's impossibly cheap. You cannot manufacture a 30Ah LTO battery anywhere near $20USD. Market price should be around $100USD.

I'm going to get a quote. If they keep anywhere within a bulls roar of $20USD, I'll order 10 to make a booster battery for my dad's solar battery (Currently 3kwh LiFePo4 - good capacity, but a bit too much sag. A 10C LTO battery for $200USD + shipping and taxes would be an absolute steal.

Hell, if they send me 10 and they all check out as 30AH and 10C, I'll order 200 from them, and build my own off grid - As you can see from their specs, they are supposed to last 30k cycles, with almost no capacity loss over time.

 

[Gazza]

You've got me thinking again. This is an LTO battery:
https://www.alibaba.com/product-detail/Fast-charging-deep-cycle-Lithium-titiant_60609356807.html?spm=a2700.7724838.0.0.0ZO6nw

It's impossibly cheap. You cannot manufacture a 30Ah LTO battery anywhere near $20USD. Market price should be around $100USD.

I am looking at 17x Prismatic Lifepo4 3.2V 100AH Cycle Life >2500.
Each - 2.5-3.65V
Bank - 42.5-62.05V
-----------------------------------

Lithium titiant battery 2.4V 30Ah LTO cell.
Model Number: OSN-LTO-66160
Each - 1.5-2.7 V
23 cell:
Bank - 34.5-62.1

These might be a good option.
How do we recalculate capacity based on 42.5v Minimum?

 

[999zip999]

Don't believe everything on the web.