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

[EricSan]

I’ve never had any trouble with adjustable pots either and I’ve installed literally hundreds of them in my projects. The surprise is that the one on the charger board is a Bournes pot (reputable brand) - the exact ones I’ve always used. I also like that the BMS was there with a current limiter to prevent things from truly going sideways. In addition to the BMS setting, my battery box is well fused, so there was a second layer of protection in place. Diagnosis was quick and the solution was even faster, so it’s all good now.

 

[EricSan]

Here is some voltage data as reported by the Viofo A329T camera from one day's worth of recording while I was at work. I really love that feature!

7:15a - 14.23v (artificially high voltage, charging just stopped as I arrived at the office)
8:00a - 14.16v
9:00a - 14.09v
10:00a - 14.03v
11:00a - 13.99v
12:00p - 13.97v
1:00p - 13.95v
2:00p - 13.95v
3:00p - 13.93v
4:00p - 13.91v
5:00p - 13.86v

Overall, this is excellent performance - nine hours of low bit rate record time with three cameras (Viofo A329T in 2-ch mode, 2-ch Viofo A139 Pro, and 4-ch Vantrue N5S) running only burned 0.3 volts from my larger 1104Wh LTO. This is exactly what I was looking for - a parking battery that would last at least a full week with multiple cameras running.

 

[ujsc]

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.

EDIT: I later upgraded this 7S battery to 6S with more features, see post #368 and subsequent posts.
EDIT: Also see post #25 for 4S battery later upgraded to 5S

Correct sourcing of affordable LTO batteries remain a problem..

 

[GPak]

...
Correct sourcing of affordable LTO batteries remain a problem..

That's true, but nowadays the situation isn't as bad as it was 5 years ago when Will reviewed LTO.
Different capacity and form-factor LTOs are available on Ali-Express, quite affordable, although, I think most are reconditioned used cells.
Will is not always right (I believe he posted a follow-up video with some corrections), however I have a lot of respect for his work; he has done a lot for the DIY Solar community.
For solar systems, which are typically located in a heated building/garage in winter, he is right - using LTO is probably not very justified, especially considering that the capacity of solar power systems is in kilowatts and tens of kilowatts, so the cost of the cells is a significant factor.

But for dashcams, LTO is the best option in my opinion, especially in regions with cold winters.
With an LTO battery compared to the same capacity LFP, you will get:

Pros:
- Year-round, fully functional uninterrupted and worry-free operation.
- The safest battery available
- The longest service life (up to 5 times more charging/discharging cycles).
- Calendar aging is almost nonexistent (unlike Will's statement)
- The fastest charging speed, if desired (up to 3 times faster) - a lot of people don’t drive/commute long enough to fully charge their relatively low capacity dedicated batteries.

Cons:
- A bit more expensive (only the cells; electronic components are the same)
- Approximately 25% larger size along the XYZ axes due to about 100% difference in volumetric energy (only the cells; electronic components are the same)

BTW, I also assembled the LFP battery with some discussions of component selection and the drawbacks of low-capacity dedicated batteries, and the first post has dimensional comparison and photos of roughly the same capacity LTO vs LFP here:

https://dashcamtalk.com/forum/threads/lfp-lifepo4-battery-for-parking-192wh-diy.51355/

 

[EricSan]

sourcing of affordable LTO batteries remain a problem

LTO is not a common battery chemistry yet. I suspect that will change in a few years. In the meantime, I’ve been sourcing LTO cells from batteryhookup.com. The first set of LTO cells were new and unused cells. The second set that I purchased are reclaimed/used and are still available on their webpage. Their capacity measures as new.

Their energy density is lower than that of LiFePo, so they are physically larger as GPak points out. This is not a concern for me. They work better in extreme temps and will far outlast LiFePo cells in terms of number of cycles. These attributes are important to me.

 

[EricSan]

Gonna be a good test of LTO working temp range this week! Forecast is in degrees F:

 

[EricSan]

Eat this, LiFePo batteries…. There are many places that get far colder than central Pennsylvania. We’ve been subzero at night nearly all week.

The self-heating of the BMS that draws a constant 0.75w or so seems to provide a small heat source that keeps the battery pack slightly warmer than ambient which is -8F/-22C. I've set the low temp charging protection limits in the BMS to -20c. Haven't gotten there yet, but tonight is supposed to be even colder - not sure that I'll be out of bed early enough to catch the low temps tomorrow morning.

 

[GPak]

Even here in the south, temperatures dropped to up to -6°C (21°F) last week, and tomorrow and Sunday night it's expected to drop to -7°C (19°F) !
I'm not sure our local palm trees will survive.

 

[EricSan]

I've been watching that storm, looks like there's going to be some problems in the south over the weekend. Hope it doesn't impact you!

 

[EricSan]

Lots more LTO batteries in stock at Batteryhookup.com if you are interested in making your own parking battery!