LTO-Titanate, recent flood of cells on EBAY

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The last time I checked (a few months ago), LTO cells were rare, whether new or used. Today, there are quite a few selections. LTO chemistry (Lithium Titanate Oxide) is exceptional due to its rated number of cycles, typically in the 7,000 range. This is not a typo, common 3.7V Li-NCA/Li-NCR in our beloved 18650 formats, are sometimes rated as 1,000 cycles if cared for and you don't charge above 4.1V per cell. The 3.2V nominal LiFePO4 is sometimes rated at a couple thousand cycles.

Best info I can find says LTO is a 2.4V nominal cell, with 1.8-LVC and a full charge of 2.85V (I just googled a discharge graph, and it appears that there is a long and flat middle, with no usable range under 2.2V, or above 2.6V)

If making a 12V pack, five cells in series (5S) would be 12.0V on the nose...11.0V LVC, and a full charge of 14.25V

The full charge number intrigues me, since a typical car alternator produces 13.8V (2.76V per cell), so charging a "suitcase" pack from your cars electrical system would be a great option. I'm fairly certain if you used only five large cells (none in parallel), you could get by safely with no BMS. The thermal runaway characteristics (fire safety) is about the same as LiFePO4, much better than average...energy density is about half of NMC, so...twice the battery volume required per the same Amp-hours of range.

7,000 cycles...dayum! (some claim 14,000?)

edit: LTO seems to perform well when cold, can go to zero volts with no damage, and are known for high charge and discharge rates (30C is common in ads).
 

Korishan

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Wow, nice numbers there. Prices?

only problem is we'd need more packs in series to get 48V :p
 

Korishan

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http://www.batteryspace.com/Lithium-Titanate-Battery.aspx said:
Model# |Capacity/Voltage | MaxDis. |Max Chrg |Diameter X Height
0407 |1.5mAh / 2.4V |30C |20C |4mm 7mm
7210 |6mAh / 2.4V |30C |30C |7.2mm 10mm
1010 |15mAh / 2.4V |30C |30C |10mm 10mm
1015 |30mAh / 2.4V |30C |30C |10mm 15mm
1020 |40mAh / 2.4V |40C |20C |10mm 20mm
1030 |80mAh / 2.4V |20C |15C |10mm 30mm
1335 | 200mAh / 2.4V |20C |15C |13mm 35mm
1450 |500mAh / 2.4V |30C |10C |14mm 50mm
1650 |600mAh / 2.4V |15C |10C |16mm 50mm
1865 |1100mAh / 2.4V |27.27C |5C |18.7mm 65.3mm
1865 |1350mAh / 2.4V |30C |5C |18.7mm 65.3mm
LTO 1020 Rechargeable Cell: 2.4V 50 mAh, 2.0A rated 0.12Wh (0.015)Your Price:$7.50
LTO 1450 Rechargeable Cell: 2.4V 500 mAh, 15A rated 1.2Wh (0.15)Your Price:$9.95
LTO 1865 Rechargeable Cell: 2.4V 1100 mAh, 30A rated 2.64Wh (0.33)Your Price:$11.95
 
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Just found out LTO performs well when cold, can go to zero volts with no damage, and are known for high charge and discharge rates (30C is common in ads), so I just added this to the top post....

Today, the most common cell on ebay is the 11-Ah flat foil pouches, lowest price seems to be $100 plus $20 shipping for 12, $10 each, the brand is Kokam / Altairnano

There is also a pallet containing 100 cells, $6500 plus $280 shipping, $6.80 per cell.

Dimensions are 207mm X 115mm,...8" X 4.5" not counting tabs

3/8" thick, 13 oz's

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There are also 22-Ah cells, which I thought were just paired 11-Ah cells, but...the drawing shows them as being larger, 207mm X 131mm / 8.2" X 5.2" (plus thicker)

Many of these were packaged and labeled as a 6S / 12V pack. This is odd to me, since 13.8V from a car alternator would only be 2.33V per cell (at 6S), barely reaching the nominal 2.4V, and nowhere near the 2.85V that it can be charged at.

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There are a few Toshiba LTO "SCIB" cells, 20-Ah each inside a metal case. $280 for six ($210 plus $80 shipping), $47 each

dimensions 116mm X 106mm...22mm thick

4.7" X 4.2"....0.9" thick
 

BlueSwordM

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Where and how the DUCK did you find Lithium Titanate cells?

They are expensive AF, but they have crazy high discharge rates on(100C can be achieved on the power optimized cell), crazy high cycle life(10000+), and can be ultrafastcharged with no stress, at up to 10C, charging in 6-15 mins, and are extremely safe.

They do have energy density equivalent to NiCD though, without all of its drawbacks.
 
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DarkRaven

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LTO cells are super interesting, I've been following the technology for some time. But as with any release of a new technology to the market it takes some time.

Earliest reports that I'm aware of date back to ~2008 when Altairnano cells were planned to be used in a car, the Lightning GT, with initial deliveries in 2009. That hasn't happened until now though. However they are still working on it, seems like they had some funding issues and planned to release a manufacturing plan in late 2017: https://en.wikipedia.org/wiki/Lightning_GT
Can't find anything on that though so I guess that didn't happen either.

Around the same time Toshiba went public with its Super Charged Ion Battery (SCiB) which was (and maybe still is) used since 2008 for certain e-bikes and since 2011 for e-cars. They have also shown a laptop battery prototype in 2008 but that hasn't happened for real as of now. In 2014 they've installed large scale systems in Japanese wind power projects for testing.

Swiss/German company Leclanch reported that they were building a factory for LTO cells in 2012 and that actually did happen, they are selling their "TiBox" since 2014. A 3.2kWh energy storage system for PV systems at home: http://www.leclanche.com/fileadmin/...ll_business/leclanche_tibox_en_2014-11-03.pdf
I love the picture with the happy family with the TiBox sitting in the living room :D
The cells are actually made in Germany, in a small town called Willsttt, at a former BASF factory. According to a report from 2015 they are focussing on large industrial size stationary systems and smaller ones for home use and also on energy storage for ships, but especially not for cars.

GWL Power / EV-Power sells LTO cells in 18650 and pouch formats: https://www.ev-power.eu/LTO-technology/
They only list the 30Ah pouch cell, however I have seen 10Ah and 40Ah in some German shops as well and they seem to come from the same manufacturer.

So, yeah, LTO cells are a real thing and they are interesting. But they are still a niche and public awareness is only rising recently. Only a few forum posts and blog posts can be found, most of them not earlier than 2015/2016. It will probably take some additional time until they have reached the availability and price and choice of formats of todays LiFePo4 cells.
 

Chiptosser

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Can you elaborate? What sizes of LTO's are you using? Did you buy new, or reclaim from something?
What are you using them to do?


Where are you located?
 

inwo

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My first post must have been rejected, as it had information about where to buy.
The recent USA supply is nib old stock 11ah.
There are about 15,000 left in the pipeline.
The best buy is by cutting eBay out of their 10%. ?
Ive seen them listed on es 12pcs for $100delivered conus.

As I've been using them so long, I know which bms and balance chargers work best with them.
Also testing some of the 2.7v super cap shunt balancers with them. The ones with ledsare nice, as you can charge and recharge until all leds come on at the same time.
 
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"I know which BMSand balance chargers work best with them"

...I'm intrigued, please continue...links?
 
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spinningmagnets said:
The last time I checked (a few months ago), LTO cells were rare, whether new or used. Today, there are quite a few selections. LTO chemistry (Lithium Titanate Oxide) is exceptional due to its rated number of cycles, typically in the 7,000 range. This is not a typo, common 3.7V Li-NCA/Li-NCR in our beloved 18650 formats, are sometimes rated as 1,000 cycles if cared for and you don't charge above 4.1V per cell. The 3.2V nominal LiFePO4 is sometimes rated at a couple thousand cycles.

Best info I can find says LTO is a 2.4V nominal cell, with 1.8-LVC and a full charge of 2.85V (I just googled a discharge graph, and it appears that there is a long and flat middle, with no usable range under 2.2V, or above 2.6V)

If making a 12V pack, five cells in series (5S) would be 12.0V on the nose...11.0V LVC, and a full charge of 14.25V

The full charge number intrigues me, since a typical car alternator produces 13.8V (2.76V per cell), so charging a "suitcase" pack from your cars electrical system would be a great option. I'm fairly certain if you used only five large cells (none in parallel), you could get by safely with no BMS. The thermal runaway characteristics (fire safety) is about the same as LiFePO4, much better than average...energy density is about half of NMC, so...twice the battery volume required per the same Amp-hours of range.

7,000 cycles...dayum! (some claim 14,000?)

edit: LTO seems to perform well when cold, can go to zero volts with no damage, and are known for high charge and discharge rates (30C is common in ads).

The battery pack that I am planning to build will be 11s and in 24V modules because at 12V the voltage range is just a bit too high or too low for use with anything that expects a standard lead brick input range. I am planning to actually have a 22s (48V) module.

The cut off is quoted at 1.5V but that is scraping the bottom of the barrel and more useable cut-off would be closer to 1.9V or higher at low C (this is if you are not pulling more than 1C) and depends on the actual LTO cell as the lower cut-off profile varies at 1C and higher.

2.7V-2.85V is typically the maximum beofre damaging the cells and 5x2.85 gives you 14.25V so above the standard 14.1V charge on a typical lead brick.

1.9V x 5 gives 9.5V, well below the nominal cut off for a lead brick, and if you are expecting to discharge at more than 1C the voltage will not hold up for 5 cells beyond around 85% capacity, depending on which cell you are using.

Changing to 6 cells pushes the maximum charge voltage requirement above 14.1V (2.35V) but would provide better hold up.

Charging to 2.7/2.85V may only get an extra 5%.... and your risking additional max charge heat stresses

When increasing up I found that 11s seems to work best (in thoery at this point) and will know in a couple of months when I get 300 cells delivered..

There are lots of LTO cells on eB and Ali and some of them are actually used and re-cycled, touted as new. All of them are well above the actual market price....
 

DarkRaven

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I wouldn't rule out 6s completely, depending on your 12V equipment. Overvoltage cutoff is often around 15.5V and undervoltage cutoff usually under 11V and above 10V. 6s LTO charged to 2.55V, discharged to 2V, 12.0V to 15.3V, is almost perfect.
 
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I'll definitely be building a second pack with 4S LiFePO4, but...

For the 6S LTO I now have, I very much like that I can get "some" charge from a 12V cars utility socket (typically a 13.8V alternator), but...when charging with solar or a wall-socket based charger, the top voltage should be very adjustable to get max Amp-hours out of it when a long run-time is needed...
 
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40Ah LTO cell 1C discharge rate (will be different for different cells)
Starting voltage 2.7V

Drops to 2.4V with only 0.81% of the capacity drawn - very quick drop at the top
With LTO the top few % of capaicty going to 2.7V charge is quite small.

1.9V cut off at 1C will have discharged 86% of the cell.

1.85V cut off will have then drawn 94.6% of the charge

Dropping to 1.5V is scrapoing the barrel and dropping a lot of V in series.
 

rev0

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Here's a charge curve for visual thinkers like myself:

LTO-DisCharge-Rates.gif


Useful range is from 2.6V to 2.2V for this example.
 

inwo

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image_muhebk.jpg


image_gvetnt.jpg

image_jtxbrd.jpg


Factory modules are 10s for 24v.
I use 6s for automotive starting battery and 11s or 12s for 24v.
32s for 72v.
 
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rev0 said:
Here's a charge curve for visual thinkers like myself:

LTO-DisCharge-Rates.gif


Useful range is from 2.6V to 2.2V for this example.

This is the 1C profile for the 40Ah cell I quoted the figures for.

image_miazzr.jpg
 
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