New Temperature Sensing Tape Enhances Safety in Vehicle Li-ion Battery Packs

Littelfuse, a leading provider of circuit protection solutions, has recently unveiled a groundbreaking product called TTape. This temperature monitoring tape is specifically designed for electric vehicle batteries and is qualified under the AEC-Q200 standard. The tape features thermally sensitive spots spaced along its length, which are connected in series to detect local over-heating.

Unlike traditional negative temperature coefficient thermistors (NTCs), TTape utilizes positive temperature coefficient thermistors. According to Tong Kiang Poo, the company's product manager, this unique feature allows for quicker alerts to the battery management system. Poo stated, "Distinguishing itself from NTCs, the profound advantage of localized cell overheating detection ensures quicker alerts to the battery management system. No calibration or temperature look-up tables are required, and only one MCU input is needed."

The TTape is designed to be used as the lower part of a grounded potentiometer connected to a microcontroller input pin. It requires a resistor (100 or 200kΩ) connected to the positive rail to complete the circuit. The ADC behind the MCU pin provides 10 or more bits of resolution.

Tripping occurs when a part of the tape reaches 58±3°C, and it resets when the temperature drops below 42±3°C. However, these numbers are subject to certain caveats, which can be found in the product's data sheet. The response time of the TTape is said to be under one second.

The operating temperature range for the TTape is -40 to +85°C, while the storage range is slightly narrower at -40 to +55°C. The tape has absolute maximums of 6V and 6mA, and it can withstand up to 2.5kV (MIL-STD-202 method 301) of dielectric voltage.

Littelfuse offers a 10 spot sample tape that is 337mm long and 10mm wide. However, the company anticipates that many applications will require custom designs. For these cases, the TTape can be manufactured up to 1m long, with up to 50 sensing spots, and in widths of 8 or 10mm. Additionally, a stitching option is available, allowing for the delivery of tapes up to 8m long.

The TTape boasts an extremely thin design, making it ideal for conformal installations. Its compact size and versatility make it a valuable tool for monitoring the temperature of electric vehicle batteries.

For more information about the TTape, visit the product page or refer to the data sheet.