Standard lithium ion cells do not function well below freezing. This is a serious limitation on the performance of electric vehicles, limiting the scope of future generation vehicles for many parts of the world. The issue also affects hybrid vehicles.
The low temperature problems can be overcome using special heaters, but these have the effect of lowering energy efficiency. The heaters function to boost the temperature of the battery packs.
For the development, BMW is to work with EC Power and the two companies have signed an intellectual property agreement. EC Power Systems is a provider of various power generating devices, such as stand-by generators, industrial engines and temporary power, for the U.S. market.
To help BMW realize a more versatile generation of electric vehicles, EC Power has developed and patented a new type of battery. The battery is called the All-Climate-Battery, and it tests the battery technology functions effectively at sub-zero temperatures. This is through, as Smart2Zero reports, generating a self-heating function. This aspect services to warm up batteries from a low ambient temperature to the optimal operating condition, within a few seconds.
The functionality applies to when the car is being driven or just prior to driving commencing. The rapid self-heating function is based on a custom material fitted into the cell and it does not need any external power source.
In tests the self-heating mechanism generates an electrochemical interface. This provides internal warm-up to 0ºC in less than 20 seconds at -20ºC, consuming just 3.8 percent of cell capacity. Comparatively heat-up is within 30 seconds at -30ºC (and consuming only 5.5 percent of cell capacity).
In terms of other specifications, the All-Climate-Battery cell yields a discharge-to-regeneration power of 1.06 and 1.4kW/kg at a 50 per cent state of charge. Trials have shown when operating a -30ºC the battery provides up to 12 times more power than with the best lithium-ion cells.
The battery has an additional advantage in that it will facilitate low-temperature fast charging in various types of electric vehicles.
