Electronic circuit for measuring series-connected electrochemical cell voltages and heating energy storage devices (batteries) for hybrid and electric vehicles


Project ID: ENG0098A

Invention Description and Novelty:
A common requirement for large stacks of electrochemical cells used in electric and hybrid vehicles is the need to measure individual or groups of cell voltages almost simultaneously. The principal problem with current techniques of voltage measurement is that a small error in measuring the nodal voltages translates into a large relative error in the measurement of segment voltages. This technology provides an electronic circuit for measuring voltage signals in an energy storage device. The voltage level of each cell within the battery pack can be monitored by a processor.

In addition, the operation of a battery is limited by a number of factors, one of which is temperature. At low temperatures the capacity of a battery to store energy, the maximum value of discharge current which can be drawn from the battery, and the cold cranking amps capability decrease substantially. Batteries used for starter, lighting, ignition (SLI) applications at cold temperatures additionally must be capable of supplying greater amounts of cold cranking current to overcome the increased engine resistance caused by decreased engine oil viscosity at low temperatures. The present invention addresses this problem by circulating energy from within the battery into lossless or nearly lossless energy storage devices and then back into the battery causing the battery to dissipate power internally. The internally dissipated power heats the battery, causing the internal temperature to rise. The circuit of the present invention does not require a complex mechanical structure, and efficiently heats the battery from the inside out. The circuit enhances the portability of batteries into cooler operating environments by using the internal energy of the battery for self-heating.


Electronic circuit for measuring voltage signals in an energy storage device in hybrid and electric vehicles. In addition, the invention is ideally suited for heating electric vehicle battery assemblies, as well as batteries used with hand held power tools. The circuit will heat both multiple batteries and single batteries.

Value proposition:
Novel system provides advantages including:

1.     Highly efficient electronic circuit allows for a high degree of accuracy when measuring both the lowest potential cell voltages and the highest potential cell voltages, and minimizes any loss within the circuit.

2.     Provides an electronic circuit with various switched components to prevent leakage of current from the energy storage device when the circuit is not being used.

3.     Provide a means of increasing the effective operating temperature range of batteries and improving the utilization of the energy stored within batteries operating within low temperature environments.

4.     Improves low temperature charging efficiency of battery, enhances the portability of systems that employ batteries by providing means for using energy stored within the battery to self- heat the battery.


IP Status: U.S. Utility Patents Issued # 6,259,229; 5,990,661


Patent Information:
For Information, Contact:
Stephen Snider
AVP Tech Transfer
The University of Toledo
419 530 6225
Cyrus Ashtiani
Thomas Stuart
Electric Vehicle
Energy Storage
Hybrid Vehicle