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I saw arguably new and interesting lithium battery which is Lithium Titanate Battery(LTO). It has high discharge and charge current characteristic. Also, it has lower degradation graph when comparing with lithium ion battery. For further information :

https://en.wikipedia.org/wiki/Lithium-titanate_battery

I am planning to build 18s 1p battery pack. My battery cell features: 2.3 volt nominal voltage. It varies between 1.5-2.8 volts. Single cell can charge and discharge 400 amps continuously.

I assume that I don’t need a BMS because there are no parallel cells, or am I missing something? What kind of protection do I need when I charge or discharge my battery pack?

I am looking forward to hear your technical suggestions.

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Better specifications here

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    \$\begingroup\$ Link to a valid data sheet for this type of battery please. \$\endgroup\$ – Andy aka Apr 8 at 14:15
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    \$\begingroup\$ 1) you probably cannot buy this kind of battery (yet) 2) it is never a good idea to "guess" how high-energy batteries should be used, instead you must KNOW. Asking on SE EE isn't good enough as few here (if any) will have experience with this type of batteries. 3) no protection on batteries which can deliver 400 A doesn't sound like a sane idea. At least add a fuse. \$\endgroup\$ – Bimpelrekkie Apr 8 at 14:16
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    \$\begingroup\$ I'm pretty sure you'll need a BMS to control how it charges and discharges. What is required will depend on the cell, which you'll need to get a datasheet to be able to answer. If you point us to the cell datasheet and tell us what you want out of it, we might be able to help you. \$\endgroup\$ – Puffafish Apr 8 at 14:31
  • \$\begingroup\$ Thank you for your suggestions. Link of the product is indicated : zhyle.com/en/sohw-6495.html \$\endgroup\$ – Burak Bozdoğan Apr 8 at 16:04
  • \$\begingroup\$ Also there is real life load test to have better understanding of how much power this battery can drain : youtube.com/watch?v=tncPz4lQUzU \$\endgroup\$ – Burak Bozdoğan Apr 8 at 16:16
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Short: You very likely need a balancer.
This page quotes a user who says his SCIB LTO batteries work well without one. Other people sell LTO balancers and other brands are generally 'less reputable' than Toshiba's SCIB.

Longer: There is no reason to expect a string of more than a few LTO calls to not need a balancer. Balancing is required when small differences in cell characteristics, due to initial and/or lifetime characteristic differences, cause cells to age differently, to have different capacities and so to charge and or discharge in slightly different manners. The result is that some cells will reach either charge or discharge endpoints before others. Continuing to charge or discharge the series string in those conditions will drive the cells into disallowed conditions and may result in cell or whole battery pack destruction.

The "good news" is that LTO balancing should be no harder than for standard LiIon cells - except that, if charging is carried out at the fast charge rate then or at the maximum permissible charge and discharge rates the switches used will need higher current ratings for a given cell Ah capacity. It would be possible to voltage monitor all cells in a string and enter balancing mode at lower charge rates when any one cell reaches its permissible limit.

LTO cells typically allow fast charge at 10C and maximum charge at 20C so a 40 Ah cell will typically fast charge at 400 A and have a max allowable charge rate of 800A.


Notes:

LTO (Lithium Titanium Oxide) batteries have been available commercially for 'some years'. The Toshiba "SCIB" LTO battery was introduced in 2008.
Suzuki use the Toshiba "SCIB" LTO battery in part of the battery in a number of their electric vehicles.

LTO differences compared to LiIon include:

  • Substantially higher charge and discharge rates, due to the use of high surface area Lithium Titanate 'nano crystals' rather than Carbon on the Anode. An area increase of about 25 x compared to carbon yields the increase in charge/discharge rate.

  • Somewhat lower and higher charge and discharge temperatures.

  • Substantially higher claimed cycle life at 100% DOD. Claimed lifetimes vary quite widely with manufacturer and "Caveat Emptor" applies with respect to lifetimes and utility of cells from little known manufacturers.

Toshiba continue to announce 'improvements' to their SCIB cells. If Toshiba are still learning, other manufacturers and/or their users also are.

In the Suzuki EVs the LTO battery is usually used as a "front end" to the main LiIon battery, allowing fast charge and discharge for energy regeneration and hard acceleration purposes. LTO chemistry has lower energy density than standard LiIon technology making it unattractive in mobile applications where its significant improvements over LiIon are not highly valued.


Superb LTO discussion page - recommended!

Good LTO EV bike article.
He uses balancing boards intended for use with super-capacitors. Obtained on ebay here


Analog devices active cell balancing during discharge.

Information page
and PDF


LTO dedicated balancer

A "Sort of datasheet" for Yinlong 40 Ah LTO cells


EEtimes LTO introduction

Specific energy: approximately 30-110Wh/kg
Energy density: as high as 177 Wh/L
Specific power: 3,000-5,100 W/kg (peak load)
Discharge efficiency: approximately 85%; charge efficiency over 95% (low-rate)
Energy/consumer-price: 0.5 Wh/dollar
Service or shelf life: >10 years (some to 20 years)
Self-discharge: 2-5 %/month
Cycle durability: 6,000 cycles to 90% capacity (some models >10,000 cycles)
Nominal cell voltage: 1.9 to 2.4V (Toshiba SCiB cells 1.5-2.7V operating; 2.3V
nominal)
Cut-off voltage: 1.5V typical (some at 1.7V)
Temperature: -40 to +55°C (extended models)
Charging technique is using standard constant current, followed by constant voltage until the amps threshold is reached.

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Caveat Emptor "specifications" for Yinlong 40 Ah cell.

enter image description here


Toshiba SCIB LTO home page

SCIB news December 2018

and here

Demand for SCiB™ is growing fast, and Toshiba is expanding production capacity through capital investment and alliances. In Japan, the company will construct a new production facility in Yokohama, Kanagawa prefecture, and reinforce the current manufacturing facility, Kashiwazaki Operations in Niigata prefecture. Separately, in 2017, Toshiba, Suzuki Motor Corporation and Denso Corporation agreed to establish a joint venture company to produce automotive lithium-ion battery packs in India, and Toshiba will also collaborate with Johnson Controls Power Solutions in the U.S.

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  • \$\begingroup\$ WTG Russ , good answer +1 \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Apr 9 at 1:35
  • \$\begingroup\$ I find it interesting that battery suppliers with 12 mos warranties for AGM only warrant for 1month unless you use a balancer. Because all battery have bigger tolerance e-caps for Farads and ESR unless within the same construction like 6 cell lead acid. Same applies to all Lithium cells unless from exactly the same batch. No wonder users despair about shorter than expected charge cycles when no balancer is used. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Apr 9 at 1:40
  • \$\begingroup\$ @SunnyskyguyEE75 Many LiFePO4 sellers make claims like eg they can be subject tom 100% DOD and give 2000 cycles. I bought 2 LiFePO4 12V x 40 Ah batteries (4 cells each). Their warranty only applied if you bought used their discharge monitor, did not discharge beyond 70% DOD in normal use and if you ever reached 80% DOD you had to contact them and follow their instructions. Given that these requirements are vastly tighter than what most sellers advise one does indeed wonder about results. |... \$\endgroup\$ – Russell McMahon Apr 10 at 12:11
  • \$\begingroup\$ ... Winston are a reasonably well established LiFePO4 battery manufacturer. They make 12V lead acid replacement LiFePO4 batteries with 4 cells sealed in a case and no access to the intercell connections. Almost all sellers of these internationally advise that they may be 100% discharged. I found a German resellers site which listed a number of brands of LiFePO4. For deep discharge they recommeded various brands with access to the intercell connections and so balancing capability. For the Winston batteries they recommended float use with only occasional deeper discharges . As you'd expect. \$\endgroup\$ – Russell McMahon Apr 10 at 12:11

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