LTO (Lithium Titanate Oxide) – The Ultimate Battery for Dash-Cam parking recording (DIY)

[GPak]

Before I start on LTO battery, I want to remind / let you know, that currently I am running two Viofo Mini2 Dash Cams, front and rear, using, off-the-shelf LFP based Power Station, which provides a lot more energy capacity and versatility for a lot less money compere to dedicated Dash-Cam Batteries.
I believe that use of suitable LFP based Power Station is the simplest, the most affordable and probably the best, option available for a parking battery. It is safe, full of functionality and very easy “Plug and Play” installation.
Here is the link to the thread with all the details, LTO is next:

Parking Battery-Power Station, 3X capacity and 3X cheaper than dedicated options + extra functionality

First, thanks to the members of this forum for posting great reviews and comments to help people like me choose the DashCam that suits their specific needs. Now, I want to share my project here and maybe help people, who do not want to mess with a car battery and fuse box but are hesitant to...

dashcamtalk.com

 

[GPak]

Now on LTO:
As good as LFP batteries are, from the safety stand point and for the Dash Cam application, LFP Batteries have a one major shortcoming - significant loss of usable capacity and most importantly the inability to charge at sub-freezing temperatures.
Even so, I live in a warm climate, we still get several days of sub-zero temperature here, and the freezing conditions contribute to a bad road conditions and accidents, this is when the Dash Cam is needed the most.
You can imagine how important this is for drivers living in a cold climates with long periods of frost.

The main reason for this project is the superior low temp performance of LTO chemistry Battery, capable of charging/discharging at deep sub-freezing conditions, while having similar to LFP hot temp performance.
Not less important is that LTO batteries have a superior life longevity and are the safest batteries out there (even better than LFP).

The goal was to build simple and affordable LTO Battery Pack, capable and feature reach and with all the required protections, using off-the-shelf inexpensive components, so anyone with basic DIY skills could build it.

For starters, here are couple of videos. One for Viofo A229 Plus 2ch parking duration test and the second one showing charging after the test.
Also a couple of pics showing early stage charging tests, note, that there is no BMS yet.
I will post more videos and pics as we go.

 

[GPak]

After some research, I choose 20Ah, 46Wh prismatic LTO cells, which are relatively compact, and available for about $15-19 per cell at Batteryhookup and on AliExpress.
These are Toshiba SCiB cells, originally designed and build by Toshiba.
These cells are kind of “new”, i.e. re-packaged in China, from original Toshiba packs and never been cycled before, according to Batteryhookup.

Here is sellers (Batteryhookup) description:
“These batteries have never been cycled and they are rated for over 20,000 cycles.
They were recovered from unused EV modules.
Threaded posts have been laser welded so you can easily assemble with nuts.
Every battery tested above 20ah.
Laser welded M5 studs were added for easy assembly and blue shrink wrap as well for insulation.
Recommended max continuous charge rate 60a (3c)
Recommended max continuous discharge rate 160a (8c)
10 second Pulse discharge rate 500a (25c)
Fully charged voltage 2.8v
Fully discharged voltage 1.5v
Dimensions 106 x 116 x 22mm
M5 nuts not included.
These are one of the most powerful prismatic cells with the highest cycle life.”

The cells came approximately 53% charged and within 0.003V from each other! Excellent!
The rated capacity per cell is 46Wh, at 2.3V and 20Ah.
The capacity of the 7S Pack is 7*46=322Wh
I tested fully charged Battery pack (2.7V per cell, 19V for pack) at constant 4A (0.2C) discharge rate and got 328.5Wh or 102% –Excellent!

Couple of Links:
https://batteryhookup.com/products/2-3v-20ah-lto-prismatic-cell
https://www.global.toshiba/ww/products-solutions/battery/scib/about.html

Here is speck for the same battery on Ali-Express:

 

[GPak]

Video on LTO SCiB safety from Toshiba

 

[GPak]

The LTO Battery pack can be built as little as in 3S1P configuration (just 3 cells, for 138Wh capacity) and up to your imagination.

I choose 7S1P configuration pack (322Wh total capacity) for the one main reason,
- To be able to support 12V system directly from the battery, without additional converters, to use unmodified original Dash Cam Hardwire cables, including original Viofo HK4 cable.
7S configuration minimum cut-off voltage is right within HK4 voltage regulator’s 11.8V-12.6V cut off range.
7S max charging voltage is about 19V, however HK4 voltage regulator is programmed to treat anything above 18V as 24V Battery and will cut off power at above 18V thinking “it is too low for 24V battery”.
For this reason, I limited max charging voltage to 18.06V (2.58V per cell), nevertheless, the Battery pack at 18V charges to 99% of rated capacity, when discharged by Dashcam's trickle power consumption!

6S1P configuration also can be used for 12V system, but with deeper voltage limitations, if standard LFP charger like "Victron" is used, or it will require combined Buck/Boost CV-CC converter, which I was unable to find at the time.

These Batteries are simply phenomenal!
While waiting for BMS from China, I cycled this batteries without any battery management system (BMS) many times in 6S, 7S and 8S configuration.
At the end of charge and at the end of dis-charge worst couple of cells are about at 0.020V dis-balance, which is good by itself!
But, once charge or dis-charge is complete, battery pack self-balances back to within 0.007V! in a few minutes.
Also when dis-charged to cut-off 12-12.6V, once load is removed, voltage quickly, in about couple of minutes, goes up to 2V per Cell or 14V for pack!

Here are the possible configurations I was evaluation:

 

[GPak]

The main challenge when working with LTO was to find suitable components.
The Charger was the biggest challenge, almost show stopper.

I was unable to find dedicated Charger for LTO in any cell configuration, never mind 7S, I guess they do not exist because LTO cells come in different verity with different voltage ranges.
LFP charger at 14.4-14.6V could work with 6S configuration in exchange to significantly limited charging Voltage (2.4V per sell vs 2.7V required).
I believe Victron DC-DC LFP charger can be adjusted to 15V, still only 2.5V per cell.
But the main reason I pass on 6S and Victron charger was due to price, at around $160 for 18A version and $210 for 30A version DC-DC charger!

My entire 7S, 322Wh system cost is about $200!

So, universal Buck/Boost (Step Down/Step Up) voltage converter with CV-CC (constant voltage / constant current) was the only choice.
Since voltage range of 7S Battery pack is 12.6-18V and the car alternator provides up to 14.4V, combined Buck-Boost CV-CC converter was needed …… but not available in needed power rating (20A input).

I found two suitable Boost converters, but the difference between 14.4V charging voltage and 12.6V fully discharged battery voltage was a concern and rightly so pointed by @DigitalCorpus.
(Boost converters require input voltage to be less then output)

With no other choice, coming next, will be videos of testing Boost converters at lowest LTO battery voltage (about 12V) from car alternator/electrical system at about 14.4V.

 

[GPak]

I had a really hard time figuring out how to fix the orientation of the video, for some reason YouTube doesn't have the option to rotate the video, weird.

Anyway, knowing (from previous Power Station experience) that car/alternator voltage immediately drops from 14.4V to about 12.7V as soon as load is applied, I decided to test these CC-CV Boost converters/chargers to see if they will work, hoping they have enough build-in cushion before voltage equalizes.
(Alternatively, I could limit Battery low end to about 14.4V by BMS, but that would make HK4 low voltage protection irrelevant for normal operations, and actually a backup protection in case BMS’s 2 level protection fails).

Nevertheless, both CC-CV Boost converters/chargers did work, I tested several times up to 12V min LTO Battery pack.
Here are some test videos, in the last video, I adjusted current and replaced fuse for 200W charging rate.

 

[GPak]

More on Chargers for LTO:
I recently finally found and ordered a universal CC-CV Back/Boost combo converter rated for a max current of 20A, and max power of 300W.
Additionally this Charger supporting MPPT, but that is more for solar panels and not needed for DC-DC charging.
Delivery time for the charger is 2-4 weeks shipped from China.
Since my LTO Battery is testing inside of my car now (functionality/reliability), I will order more SCiB cells for this charger testing.
If it works it could be universal charger for any LTO sell configuration as shown in spreadsheet (see post #5).
Specifically it will allow 6S configuration to be workable with Dashcam’s original 12V hardwire cables, for some, that could be important for whatever reason.

Although most of this Hardiwire kits convert 12V to 5V, so in my opinion 5V system is the way to go, simply cut-off voltage regulator box from hardwire cable (all the necessary protections are provided by BMS).

Here are couple of linkson Amazon, the same charger from Ali express is about $22 shipped, but keep in mind, that I have not tested it yet.
https://www.amazon.com/gp/B0C6NF64W7
https://www.amazon.com/gp/B0BTPS4N5J

 

[GPak]

On BMS (Battery Management System) for SCiB LTO Battery pack:

Unlike LFP, which is usually standard 4S/8S/12S/16S/… configuration for standard 12V/24V/36V/48V/… systems, LTO chemistry is more diverse in voltage range and possible configurations, plus in order to use HK4 hardwire kit, some voltage limitation is required, hence universal, adjustable smart BMS is needed for Battery pack.
Smart BMS for LTO is not that common but available on Ali Express.
I used ANT BMS, 40A, 7S-16S, with Bluetooth, other brands are also available on Ali Express.
Unfortunately nothing is available on Amazon, which I like for quick delivery and easy return process if needed.

Technically, you can run this SCiB Battery even without BMS, but I do Not recommend it.
Charger will protect it from overcharging and Dashcam's hardwire kit will protect with low voltage cut-off (7S and 6S), for other configurations, 5V buck converters with low voltage cut off would be required.
Some people use active or passive balancers instead of BMS, mostly for “Yinlong” LTO cells.
I cycled SCiB cells in 6S and 7S pack many times before installing BMS, they go slightly “dis-balance” approx 0.04V the worst, at very end of charging or very end of dis-charging cycle (which is very small by itself and does not require balancing), but even better, SCiB Cells quickly self-balance once the charging or discharging is complete, to only approximately 0.003-0.006V difference! I did not see any accumulation of dis-balance, during this cycles, maybe I didn't cycle them enough.
After BMS connection, so far, I never saw BMS to automatically turn-on balancing, and I never manually force balance.

Nevertheless, I highly recommend BMS, because it provides dual level of protection and combined with charger and hardwire kit it is triple level of protection.
(I am in aviation, redundancy and fail-safe design is in my blood )
I also like to have an App, it is very informative and convenient to monitor status of the Battery.

Next I will show what the Battery looks like inside

 

[TheSpanishInq]

Nevertheless, I highly recommend BMS, because it provides dual level of protection and combined with charger and hardwire kit it is triple level of protection.
(I am in aviation, redundancy and fail-safe design is in my blood )

Love how you are thinking and what you are sharing!
Better to have multi layers of protection, don't need a run off alternator to fry the battery pack/cause a fire and burn down your car!
IMHO a battery management system is a requirement, not a recommendation.

 

[GPak]

...
Better to have multi layers of protection, don't need a run off alternator to fry the battery pack/cause a fire and burn down your car!
IMHO a battery management system is a requirement, not a recommendation.

Absolutely Agree, BMS is Required for safe operations!
It protects not only the battery pack as a whole, but also individual cells.
Just wanted to emphasize, what the difference is between having a BMS and not having one.

 

[GPak]

Here's what the LTO Battery looks like inside.
I filmed this prior display installation, and fully assembled Battery is already posted (post # 2).
Don't be discouraged by a lot of of wires, as I didn't cut them to size and soldered, but rather use wire spade connectors, so I can swap out the internals to test different configurations.
Also instead of using switch, the easier and simpler solution (less wires) would be to use dedicated output connectors for 5V and 12V.
Also dedicated input connector for ACC cigarette lighter/Fuse Box, could be used eliminating Relay, if you are not worried to stress the car battery during start with additional 10A-20A charging current.
Edit: I noticed I misspoke in video, LTO cells are SCiB cells originally built by Toshiba.
Next, I will post schematic for the Battery with all the option, I am working on it.

 

[GPak]

Here is the principle diagram for the LTO Battery for Dashcam
BTW, this same diagram can be used with LFP cells if you want to build LFP battery, except voltage range for LFP is different.
If it looks to you a little complicated, it is really not, this is for all the options combined.
Next, I'll show you how simple an LTO Battery can really be, once you decide on the final system setup.

 

[GPak]

I have couple of promised videos which I am unable to rotate in YouTube Studio, if someone knows how to rotate the video please help.
Videos are loaded into my YouTube playlist upside down and rotated 90°, unfortunately original videos are permanently deleted from I-Phone, so I cannot fix them there as I did wit previous videos.

For now, here are the Battery diagrams for 12V and for 5V system, to show how simple it can be.
It is basically Battery with BMS and the Charger, plus pair of 5V converters for 5V system.
And of course you can add some good to have features, like Display and TDR.

 

[GPak]

Finlay found the way to move video back to I-phone to rotate and upload to YouTube again.
Here is 12V system, it is as simple as it gets, 5V system next

 

[GPak]

And here is 5V system:

 

[GPak]

It has been two weeks as I installed LTO Battery in my Jeep running two Viofo Mini/2 dash cams, the same 5V setup as for Power Station.
So far it works without any issues whatsoever! With my daily 45min driving and 17h parking plus occasional grocery shopping, battery stays always charged at about initially installed 60±20% SoC (State of Charge).

The only issue, I am looking to correct is that BMS is rated at 40A, and it is accurate, working with Amp’s during charging but it is not that accurate with mili-Amp’s, and mili-Amp’s is what DVR consumes during parking.
Since BMS calculates Battery SoC percentage based on Ah, it is basically useless. I can calibrate Amp’s reading in App to be accurate for mili-Amps, but then it is inaccurate during ~10A charging.

On the bright side everything else is very accurate, including voltage reading, and it is easy to estimate battery SoC based on voltage, that is how my indicator on the box is calculating SoC.

Using voltage to calculate Battery SoC works very well for DVR applications because there is no noticeable voltage drop with mili-Amp consumption.

 

[vlgligor]

Thank you, GPak! Love the work you have done, the attention to details and the clear instructions and explications. I have few questions:

1. Could you share the time-delayed relay brand you are using? On Amazon Germany I found the HELLA 5HE (0s to 900s adjustable @~43 EUR), and on Amazon.com I found the Chinese 10s delayed iJDMTOY, Aharon and Hoypeyfiy 2pcs, all around 30 USD with shipping.
2. Regarding the 2 pcs of 5V step-down converters, their only function is to replace the HK3/4 and one of them is only to sense the AUX, is this right?
3. Isn't it possible to just get rid of the cut-off voltage protection inside the HK and use this instead of the two 5V converters? (less shopping, since I already have the HK3)
4. USB-C cable: could you share the pin-out connection to identify the power & aux wires?
5. Is it possible to limit the charging current inside the BMS app?

Thanks!

 

[GPak]

I have few questions:

1. Could you share the time-delayed relay brand you are using? On Amazon Germany I found the HELLA 5HE (0s to 900s adjustable @~43 EUR), and on Amazon.com I found the Chinese 10s delayed iJDMTOY, Aharon and Hoypeyfiy 2pcs, all around 30 USD with shipping.
2. Regarding the 2 pcs of 5V step-down converters, their only function is to replace the HK3/4 and one of them is only to sense the AUX, is this right?
3. Isn't it possible to just get rid of the cut-off voltage protection inside the HK and use this instead of the two 5V converters? (less shopping, since I already have the HK3)
4. USB-C cable: could you share the pin-out connection to identify the power & aux wires?
5. Is it possible to limit the charging current inside the BMS app?

1. I use Aharon, others in your list also look fine, except for the Hoypeyfiy 2pcs, which has very few and all bad reviews.

2. Correct. LTO nominal voltage is 2.3V, so in order to work with 12V HK4 cable at list 6 or 7 cells are required, but I wanted to test 5V conversion for future smaller 4 cell LTO Battery packs, and also because my Jeep (test-bed) already has 5V system DVR wiring installed (no HK voltage regulator box).
For example, 4 cell LTO voltage range is 7.2V-10.8V, that is not enough for HK voltage regulator to work, because regulator’s lowest cut-off point is 11.8V, which is higher than 4S LTO can provide, hence 5V converters are needed to run 5V directly to DVR

3. Sure you can remove voltage converter/regulator from the HK3/4 cable and use it to convert 12V into 5V, but why, for LFP you do not need 5V converters, 4 cell LFP provides acceptable 12V range, just use HK cable as is, to power DVR, it doesn't mattere where the conversion happens.
However, I actually can replace two 5V converters used in my LTO Battery (7S) with one HK4 voltage converter/regulator. I have couple of them removed from my Power Station project.
Thank you for the idea.

4. I used this USB-C Cable with Viofo HK cable and also with generic 3-wire cable, Color coding is axectly the same, Black - ground, Red - V+ power, and Yellow is signal - CC1=ACC, connected Black to Black, Red to Red and Yellow to Yellow, it works as intended:
https://www.amazon.com/gp/B0B24WVRCJAttached image is from Amazons product description and standard USB-C pin out (collar coding is the same except ground is shown green), you can connect tow images for Viofo's HK pin out.

5. No, not for the purpose you are asking. You can set charging/discharging current limit in BMS App as a protection cut-off limit, but not to charge the battery at certain current, i.e. it will stop charging as soon limit has been reached, and with regular voltage converter without constant current you will hit that limit as soon as you start charging.

 

[GPak]

It's been two month with the LTO battery in my Jeep and I can happily report 0 (zero) issues.
Battery pack is working as it supposed to; therefore, I can post now list of all components I used for this battery with links.
Also, I will post shortly couple of videos on Battery pack and the BMS App.