Lithium-titanate (LTO) is an interesting battery chemistry that is akin to Li-ion but uses Li2TiO3 nanocrystals instead of carbon for the anode. This makes LTO cells capable of much faster charging and with better stability characteristics, albeit at the cost of lower energy density. Much like LiFePO4 cells, this makes them interesting for a range of applications where the highest possible energy density isn’t the biggest concern, while providing even more stability and long-term safety.
That said, LTO is uncommon enough that finding a battery management system (BMS) can be a bit of a pain. This is where [Vlastimil Slintak]’s open source LTO BMS project may come in handy, which targets single cell (1S) configurations with the typical LTO cell voltage of around 1.7 – 2.8V, with 3 cells in parallel (1S3P). This particular BMS was designed for low-power applications like Meshtastic nodes, as explained on the accompanying blog post which also covers the entire development and final design in detail.
The BMS design features all the stuff that you’d hope is on there, like under-voltage, over-voltage and over-current protection, with an ATtiny824 MCU providing the brains. Up to 1 A of discharge and charge current is supported, for about 2.4 Watt at average cell voltage. With the triple 1,300 mAh LTO cells in the demonstrated pack you’d have over 9 Wh of capacity, with the connected hardware able to query the BMS over I2C for a range of statistics.
Thanks to [Marcel] for the tip.
Very Cool!
Just for information: many energy harvesters (TQ BQ25570, ePeas, etc.) have a highly configurable storage interface. So they easily can be adjusted for LTO, LiFePo4, etc.
The BQ25570 is able to go up to 110mA on the load side. With a small buffer capacitor this should be enough for Nordic- or STM-based radio (Meshtastic/etc.) stations.
Oh man, LTO is SUPER COOL!
I ran my car on a 6s 35ah setup, no bms (for lengthy reasons that are explained elsewhere) and it ran a TREAT.
LTO is super undervalued, anything that helps get it into the spotlight is amazing!
Googling “ih8mud LTO starter battery” and clicking the 157 posts link will send you on a deep dive, if that’s your thing.
And now for Na+ cells, please!
Author of the LTO BMS here: that should be relatively easy as the Sodium Ion battery voltage is similar to the LTO. It’s just the matter of fine-tuning firmware in the ATtiny. It’s definitely on my to-do list.
Will be looking forward to that, I have 100 Na+ 26750 I impulse bought before the tariffs kicked in. finding a BMS for my projects have been a huge pain.
Besides LTO being lesser known, a major advantage needs to be advertised: wider operational temperature range. They can be charged below freezing point. Much better for stationary outdoor usage than other Li batteries.
Awesome, I’ve a BMS for a 2S pack I’ve been designing so it’s super cool to see others using LTO cells as well.
My design is a bit different though as I ended up using a decent voltage ref and comparator for my voltage cutoffs and polyfuses for a crowbar circuit.
Interesting choice to build it as a 1S3P setup though, the nominal voltage is low enough that it makes it a bit hard to power 3.3V stuff without tossing on a boost converter.
For me the main advantage of LTO lies in its ability to be charged at very low temperatures – down to -40°C. Something other chemistries like LFP or NCM really don’t like.
Don’t you mean -40°F? ;)