ST Flex Products

Battery Electronics

Electric vehicle battery systems consist of arrays of multiple individual cells. Complex control systems monitor temperature and charging within these packs. In order to maximise service life; control of charge equalisation is vital.

All rechargeable batteries require a Battery Management System which monitors the State of Health (SOH) of a rechargeable battery monitoring current voltage and temperature from this collected data the BMS actions any corrective actions required.

The architecture which collects the data which the BMS interprets is referred to as Battery Electronics, these were initially primarily hard wired in the early batteries for Electric Vehicles. As technology has matured the use of Printed Circuit Boards to simplify the assembly process has been adopted. The space constraints and geometric demands has resulted in Flexible Printed Circuits (FPC) becoming the most common solution.

Initially Strip Tinning’s involvement in this field was for FPC’s which were used to replace conventional wiring harnesses. FPC’s brought benefits in regards to weight savings, increased complexity and easier assembly. Use of FPC technology can far exceed what can be achieved with conventional wiring solutions.

We are now seeing greater interest in our modular solutions; these Contacting Modules combine our extensive in-house knowledge in the fields of FPC, Plastic and Busbar technologies.  The end deliverable which can be adapted for cylindrical, prismatic or pouch cells delivers one unit that not only provides the electrical connection between cells but monitors the vital temperature and charging functions. This then delivers simplification of the assembly process and supply chain to our end customers.

1. FPC

A lightweight and reliable replacement for traditional wire harnesses. With both weight and space saving benefits over conventional wiring and the ability to simplify assembly whilst increasing complexity of the monitoring system; FPC’s are a win-win solution in Battery Management electronics. Traditionally Strip Tinning use PEN substrate in Battery applications as it has cost, safety and dimensional stability benefits over Polyimide which is the most common substrate FPS’s are made from.

2. Plastic Carrier

Lightweight plastic carrier to hold busbar and FPC. With an extensive in-house knowledge of plastic forming as well as an approved supply chain that covers all areas from rapid prototyping through to mass volume production of parts Strip Tinning are uniquely placed to support programs requiring plastic carriers. Strip Tinning can offer a variety of materials for these parts.

3. Busbars

Aluminium or copper primarily used to charge the cells. As well as being an active part of the charging infrastructure of an EV busbars are also the pick-up point for our FPC in regards monitoring of the cell charging process.

4. Connection to BMS

Interconnection to the electronic control unit (BMS) via proven automotive approved connectors. Strip Tinning has the capability to a fit SMD, Leaded or crimped terminal connectors to our FPC’s in order to connect into BMS modules; it is even possible for this to be achieved by direct solder attachment of the FPC to the BMS. Where crimped terminals are employed automatic equipment ensures the process is consistent, repeatable and cost effective.

5. Onboard electronics

Assembly of electronic components to the FPC. Fuses can be used to protect the system from short circuits whilst integrated thermistors are used to monitor system temperatures. The nature of FPC allows these to be sited closer to critical areas than other solutions maintaining a better level of control; they can be encapsulated to protect from moisture and mechanical stresses.

6. Busbar Interconnection

Connection of FPC feature to busbars to facilitate monitoring of cell charging. There are several methods that can be employed in order to achieve this most common method is ultrasonic welding, although solder and rivet attachment are also feasible.

Enquire about your battery electronics project today

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