Electrical

Building a solar car battery

Posted on May 1, 2013 by Daniel Chambers

It’s not immediately obvious to many people that solar cars should have batteries. If you get all your power from the sun, why do you need to lug around all that extra weight?

There are several reasons for having a battery in a solar-powered car, and most are inter-related.

To be able to operate when there isn’t any sunlight
To decouple the car’s performance from the instantaneous weather conditions
To provide a stable high-voltage bus to drive the motor, and “hang” the rest of the electrical systems off.

The WSC 2013 regulations permit solar vehicles to carry an energy storage system (in this case a battery) whose maximum allowable cell mass depends upon the chosen cell chemistry. If you use lead acid battery cells (the type you’ll find in your car at home) you’re allowed up to 125kg in Challenger class. If you choose to use lithium ion battery cells (the type you’ll find in your laptop) you’re only allowed 21kg. Why the big difference?

Lithium ion cells are extremely energy dense. That means there’s a huge amount of energy stored inside a small mass (and a small volume). The aim of the regulations is to make sure that …
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Posted in 2013 Car, Blog, Build, Electrical, Energy, Renewable technology, WSC | 1 Comment

Mechanical Team Blog- Lent Term Week 7

Posted on March 7, 2013 by pjm206

Build Progress:

Steve and Thomas welcome you to our new build workshop.

This week, a stiffener (which also acts as the steering rack mounting block) was fitted to the chassis.

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Posted in 2013 Car, Blog, Build, Cambridge, Composites, Electrical, Mechanical, News | Leave a comment

Electrical Team Blog: Lent Term Weeks 1 – 4

Posted on February 17, 2013 by Yang Lu

Significant progress has been made by the CUER electrical team in the past few weeks. After successfully manufacturing and testing our telemetry boards over the winter break, the team set about finalising the rest of the system.

Driver Controls

The design for the driver controls unit has now been finished. The aim was to keep the interface as simple as possible. The decision was taken to remove all non-essential switches and controls off the steering wheel. This increases the reliability of the steering wheel system (something which caused us issues in 2011), and also helps avoid any accidental driver inputs.

Instead, the key vehicle controls have been mounted on a single unit to the right-hand side of the driver. This contains a large reflexive LCD display to effectively display basic vehicle information to the driver, as well as switches for the on-board controls. More detailed car telemetry information will be monitored and analysed by engineers in the chase car.…
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Posted in 2013 Car, Blog, Electrical, News, Testing | Leave a comment

Inspire & Innovate – CUER & Ardingly

Posted on February 13, 2013 by Keno

Building any type of vehicle is not a simple task; it requires knowledge about mechanics, dynamics, electrics, power and safety. This year, we’re celebrating 6 years of designing, building and racing solar cars. The experience and expertise we’ve picked up along the way have really placed us in a position where we can start from a blank sheet of paper and push the boundaries with our latest design, codenamed Daphne. With a chassis weighing just 20kg, we’re all excited to get Daphne rolling in the coming weeks.

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Posted in 2013 Car, Aero, Affinity, Blog, Build, Cambridge, Composites, Electrical, Outreach, Students | Leave a comment

Our Noctua Cooling Fans have arrived!

Posted on January 31, 2013 by Yang Lu

A big thanks to Noctua for providing us with some of their latest NF-A14 FLX cooling fans for our new car.

We look forward to testing them and stay tuned for the results!

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Posted in 2013 Car, Aero, Blog, Electrical, News, Testing | 1 Comment

Electrical Team December Update

Posted on December 13, 2012 by Tim Bossanyi

During the last few weeks, we have made a good start with the detailed design of all of the electrical systems. Arrangements for the battery pack are being finalised, with the layout and electrical connections being drawn up so that we will be ready to take delivery of 442 of the world’s best lithium-ion cells in January. However, the battery pack consists of far more than just the cells. We will be using sophisticated electronics to monitor the temperature at multiple locations and the voltages of each and every cell to ensure that the pack remains safe and efficient at all times. There are also safety contactors – heavy duty switches which can open automatically to cut the power in the event of a fault. Traditionally these are weighty, power hungry devices so we are looking at new methods to reduce their power consumption and leave more energy available to drive the car.

We have also been working on the telemetry and control systems for the car, with a prototype circuit being manufactured as I write this. This will gather data from the whole of the electrical system and relay it over a radio link to the support vehicles, allowing …
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Posted in 2013 Car, Blog, Electrical, News | Leave a comment

Welcome On Board Altium

Posted on October 18, 2012 by Andrew Zhao

I would like to welcome our new sponsors Altium to the team. Altium and their UK supplier Premier EDA are supplying us with Altium Designer, software which we will be able to use to design our low-powered electronics boards. Thanks very much Altium!…
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Posted in 2013 Car, Blog, Electrical, News | Leave a comment

Dan’s Race Report

Posted on November 2, 2011 by Daniel Chambers

This is not so much a race report as a summary of the entire year’s efforts, challenges, disappointments and successes. The culmination of all this activity was Australia’s WSC 2011, so in non-chronological fashion I’ll start there.

The most frustrating thing for a group of enthusiastic engineers is to have their efforts and aspirations thwarted by bureaucracy. But that’s exactly what happened when our shipping company refused to give us our container or even accept any form of payment. We spent an unproductive and relaxing two weeks in Darwin without a car to work on. However, what we achieved in the following fortnight after we finally got our hands on the car cannot be overstated. The car arrived in a “working” condition (we’d done some driving back in the UK at Bourn Airfield) but getting the vehicle race-ready took a huge amount of proverbial elbow grease and midnight oil.

We successfully fitted new lights and LED drivers, tested new driver controls and telemetry, performed solar battery charging tests and re-wired a few things that we’d never got around to in the UK, including the rear-view camera. The mechanical guys chipped in with a new set of wheels, worked out how …
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Posted in 2011 Car, Electrical, Energy, WSC | Comments Off

The Electrical Team Lights The Way

Posted on July 20, 2011 by Lucy Fielding

The electrical rebuild has accelerated from “rapid” to “frantic” in recent weeks. Numerous tasks compete for the attention of the electrical team, from battery management systems and cell balancing, to lights and driver controls. It’s all got to be done, and recent work has focussed on getting the car ready for testing this weekend.

The battery management system (BMS) is something we’re particularly proud of. Not only does it intercept, interpret and act upon CAN messages from the Lifebatt cell management modules (CMMs), but it also monitors the current into and out of the battery via our Isabellenhütte shunt resistors and shuts off the battery from the rest of the vehicle in the event of a fault.

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Posted in 2011 Car, Electrical | 2 Comments

Battery Taxonomy

Posted on June 17, 2011 by Lucy Fielding

Those ardent followers of not only our blog but also our twitter feed (@cuer2011) will have started to hear many names float about in reference to the battery. In deference to their loyalty, and also because it makes a reasonably interesting blog post about batteries, here is a breakdown of the components of CUER’s battery.

We begin with the smallest unit in a battery – the cell. This is a single lithium-iron-phosphate (LiFePO4) cell. A cell is essentially a block of chemistry – in its simplest form, it contains two metal electrodes and an electrolyte (here, LiFePO4). What we often refer to as a battery (e.g. Duracell, Energizer) is actually just a single cell. They work by undergoing oxidation and reduction reactions at the two electrodes; these reactions are complementary and require a flow of electrons. It is this flow of electrons that provides the ‘electricity’ from the cell.

Here is one of our cells:

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