02-24-2018, 03:21 PM
(This post was last modified: 02-24-2018, 04:31 PM by spinningmagnets. Edited 6 times in total.

*Edit Reason: speling*)
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).

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).