Battery Development

Formula Student Lithium Ion Battery – FSA Compliant

Formula Student

The Formula Student Series

The Formula Student Series is an amazing event organised by the IMechE, involving universities from all across Europe competing to build race cars usually as part of their final year studies.

The teams compete and score points in a variety of events designed to push their skills not only in engineering but also business, project management, marketing etc.

In our opinion this is one of the best events we have ever seen and gives students a much clearer picture of what industry looks like.

Li Ion Batteries

The Formula Student Series has seen a number of teams moving from internal combustion driven cars to electrical driven cars. This reflects the industries move to follow suit as social pressure takes hold and the vehicle industry reacts.

The recent availability of good quality lithium cells and batteries, as well as a greater understanding of the technology, has now enabled teams to adopt this technology with a greater degree of success. Once adopted the benefits of electrical power are there to be seen.

Custom Lithium Ion Battery Design

Altertek was approached by Surrey University Racing Technology and Engineering Solutions (SURTES) to create a new bespoke Lithium Ion Battery as a backup for their for their 2017 electric race car that had to be FSA rules compliant.

The parties involved decided on a 316V – 20Ah – 6kWh Lithium Ion battery using the A123 20Ah Prismatic LiFEPO4 cells as they gave the best mix of power and energy density at the time.

The cells were assembled into modules in accordance with the FSA rules using Altertek’s own design of prismatic cell holders, allowing the cells to be held extremely close together while being held in accordance with A123s design guidance.

Altertek used 8 of their own CAN bus enabled Battery Management Systems which were configured to communicate and control their preferred charger. This controlled the cell balancing on a cell to cell basis to ensure that the cells had the maximum amount of energy needed to perform on the various events but specifically, the endurance race.

The Build

The Surrey University Lithium Ion Battery had to dimensionally fit into the car, which had already been designed. As we had decided to use a different cell chemistry to maximise the energy density for battery battery volume, space was extremely tight

The team at Altertek manage to squeeze it all in and then performed, in witness of representatives of the SURTES team, a full factory acceptance test in which the Lithium Battery was pushed to its limits, delivering a peak power output of 83kW at approximately 50% state of charge!

All the safety systems were also checked, inducing artificial isolation faults to prove the isolation monitoring system was working correctly. The SURTES team left feeling very confident the battery would perform on the day.

Handover

Once the battery had gone through its factory acceptance in witness of SURTES, the final quality checks were made to ensure all systems were functioning correctly.

This included cycling the battery a sufficient number of times to ensure that all the cells had bedded down nicely and were in an optimal state to perform on race day.

Just for good measure integrated the battery with some monitoring software so the SURTES team could view vital statistics of the battery over bluetooth to a tablet or laptop to help them perform monitoring and diagnostics.

Although this Lithium battery is a backup to their primary battery we hope to see it running soon and see it stretch its legs.

Altertek are looking forward to the continued sponsorship and working together with Surrey University.

Good luck SURTES!!

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