Battery tech is developing fast. New types are entering the market, and leaving if they disappoint (or are to disruptive such as sodium batteries). The race is on for more kWh/kg, energy density and more cycles. This post is about Lithium Titanate batteries, and a quick recap of their capabilities is :
- Nominal cell voltage: 2.3 V
- Specific energy: 60–110 Wh/kg
- Energy density: 177 Wh/L
- Cycle durability: 6000–20000 cycles
The efficiency of these cells is not great, about 80%, but the cycle life is off the wall. These batteries will last 30 years! If you build storage for your solar installation you only have to buy them once. The search code for this battery chemistry is LTO, you can find them on Alibaba.
There are two main formfactors, the cylindrical and so called prismatic cells. The round are shown in the above video. because the Cell voltage is 2.3 Volt you need 5 or 6 of them to make a 12 Volt cell. You can get 5S BMSes to charge them on Aliexpress (5S) but 5S causes the battery voltage drops too low. Now there are 6S BMSes for sale (link to the BMS from the video). The balancers need further development, but balancing doesn’t need to be a problem.
LTO cells can discharge deeply, don’t mind low temperatures and don’t catch fire. Compared to Li-ion cells they are much safer, so if they are used in vehicles or machine and remain unattended for long times they won’t suddenly cause a fire.
New LTO batteries are more expensive, but this is because they last longer. Second hand LTO batteries are cheaper, but because of the many cycles they can be as good as new. Its funny because AliExpress can be a wild west market, so whatever you buy you need to test and check to see if you got what you bought.
Discharge rates for LTO cells can be 10C! This makes it a good option for starter batteries, but lighter and smaller.
We are looking for european manufacturers. Now with the Coronavirus logistics from China are under pressure. The risk to the world of being dependent on airfreight or 45 day logistics for essential goods (if they are even being produced) is not a smart thing. We hope more batteryfactories will be build in the EU soon!