too good to be true.  But Lithium Titanate is a proven battery chemistry which has been around for more than 10-years.  So, you may be wondering: “Why have I not heard of Lithium Titanate before?  Why is no one else making LTO batteries?”  It may be that other Lithium battery manufacturers are too busy making batteries for the mass-market.  It may be that the Lead-Acid manufacturers are too big to switch-over.  We don't know; but we do know the US military prefers LTO and has even subsidized a US manufacturing facility.  We know we get calls from university research labs (and elsewhere) for custom LTO batteries (and we build them).  We know because there are a few other manufacturers who have incorporated LTO into their products for cold-weather applications.  And finally, we know because we built. for more information download the PDF

This document provides technical guidance for the use of a conventional Lead-Acid or (Lithium) Charge Controller newly equipped with 12V Titan LTO Immortal Cold-Weather Storage Batteries.  In case you are not familiar with the behaviour of Lithium Titanate, included are a few explanatory comments. For more information on our batteries, you may refer to the document “Why Choose Titan LTO Immortal Cold-Weather Batteries,”

CRITICAL CHARGE SETTINGS

1. “voltage-sag,” so when charging is complete, within a minute or so, at room-temperature, your final resting voltage will be ~0.1V below the Bulk Setting.

• At and between -20C and -40C the resting voltage will drop by a total of 0.5V – 1.2V respectively.
• The "Gel" Setting Workaround: If your controller lacks a "User" mode, the Gel Setting (14.1V–14.4V) is within BMS Specs and the manufacturers' recommendations for safe use.

2. A float is not necessary, as LTO does not suffer from the weaknesses of Lead Acid: There is no sulfation at partial States of Charge (SOC), it is tolerant of high charge rates at up to 100% SOC, and has an extremely low self-discharge rate of less than 1% per month.

3. Equalization: MUST BE DISABLED.  High-voltage equalization is not necessary, and although the BMS will prevent charging above 14.5V, there is a remote chance frequent operation will damage the BMS and disable your battery.

4. Temperature Compensation: MUST BE DISABLED (Set to 0.0mV/°C).  Even at -40°C, the internal resistance of an LTO battery is very low.

SOC READINGS

All things being equal, a Lithium battery has a higher resting voltage than Lead-Acid, and maintains a higher voltage for the majority of its cycle, then at roughly 20% SOC the voltage will drop quickly.  Because the voltage curve is so flat, traditional "bar-style" battery meters or guages designed for Lead-Acid will be inaccurate.  We recommend a shunt-based battery monitor for precise tracking.

 NOTE:

1. Because other Lithium batteries behave similarly, if you can change the SOC meter to a Lithium Setting without affecting any of the Controller settings, this will be quite accurate.

2. As a temporary measure, it is possible to just watch the guage until it starts to drop, then you know you are at about 20%.