EV.Charge case study — Shomitro Kumar Ghosh

Simplifying EV charging, one stop at a time.

Mobile appEVRewardsUX research

Overview

A mobile app that helps EV drivers find reliable stations, pay without friction and turn charging wait time into something useful — with rewards for charging at quieter times.

KEY STEP // 1

Competitive analysis

We evaluated four existing mobile apps: PlugShare, EVgo, Tata Power EZ Charge and ChargePoint.

01
AdvantagesThe ability to filter choices, and reliable waitlist and charge-status updates.
02
Pain pointsInaccurate locations, broken stations, waitlist malfunctions and poor integration of payment options.
03
OpportunitiesClearer pricing information, fewer login steps and simpler ways to reserve a station.

KEY STEP // 2

Literature review and user survey

The original prompt was a smartphone app interface for EV charging station recommendation. Our literature review looked at how mobile charging apps influence EV drivers’ charging behaviour — 15 articles from 5 publication databases, all published after 2010. A preliminary survey of five EV drivers assessed their charging patterns and behaviour. Every participant owned a Tesla, had no additional ICE vehicle and was highly satisfied using the Tesla dashboard and navigation to locate charging stations. One reported charging anxiety.

01
Intentions behind EV purchase
02
Attitudes inhibiting EV adoption
03
Charging infrastructure and its relationship to charging behaviour
04
Current mobile apps that improve the charging experience
05
Congestion control and charging-pattern prediction

KEY STEP // 3

Identified gaps in current designs

The survey and literature review revealed several inconsistencies. Barriers to EV adoption include drivers’ perceptions of long recharging periods, the inability to locate reliable charging stations and excessive wait times — along with questions about the capacity of the current electrical grid.

KEY STEP // 4

Proposed solution

Current apps already cover the basics: locating and navigating to stations, a user-friendly interface, payment, customisable filters, user support and charging notifications. EV.Charge adds two novel features intended to influence behaviour.

01
Be active outside the vehicleReframe the recharging routine so it fits the driver’s lifestyle.
02
Charge at less popular timesReduce wait times, congestion and load on the electrical infrastructure.

KEY STEP // 5

Design process

Empathize, define, ideate, prototype, test and iterate — from competitive analysis, a Google Forms survey and interviews, through personas, scenarios, Crazy 8s and group discussion, to a Figma prototype and usability testing.

KEY STEP // 6

Initial prototype design

For the initial prototype we focused on three core task flows to address primary user concerns and establish the app’s core functionality.

01
Meaningful charging-time activitiesReview stations, explore nearby amenities or play games for rewards.
02
Customisable filter criteriaFilter stations by charger type, real-time availability and distance.
03
Seamless payment integrationQuick, secure payments via multiple methods (credit cards, wallets).

KEY STEP // 7

Usability testing

A between-group study: Group 1 had never driven an EV, the control group had driven one but did not own one, and Group 2 currently owned an EV. Our hypothesis was that EV owners would make fewer errors and complete tasks faster, thanks to their familiarity with similar technology. We measured task time and number of errors, and collected feedback on navigation and overall satisfaction.

01
Task 1Locate payment methods and add one.
02
Task 2Open the map, choose a charging station and save it.
03
Task 3Schedule a reservation for later and read out any alerts.
04
Task 4Get directions, start a charging session, view the charge and submit a review.
05
Task 5Open the weekly challenge list, complete an activity and check your status.

KEY STEP // 8

Test results

Efficiency in task completion: the study did not show any evidence that EV owners took less time to perform a task. Error reduction: EV owners encountered fewer errors while performing tasks, indicating a better understanding and a better usability experience.

KEY STEP // 9

Participant feedback

01
Where participants struggledFinding the rewards section, understanding what rewards could be used for, greyed-out icons that looked non-functional, the term “task” in the weekly challenge list, and a design with too little colour.
02
Design bugsNo way back to the homepage from the charging station without stopping the charge, and weekly challenges hidden until a review was submitted.
03
What they likedThe list of nearby amenities, the game option (with requests for more variety), earning rewards and the simplicity of the design.
04
What it could changeSeveral said the rewards might encourage people to charge at public stations.

KEY STEP // 10

Improvement 1 — a clear way back home

Users found the cross button confusing because it did not clearly mean “Back to Home”, and they often tapped “Stop Charging” by mistake. We added a secondary “Back to Home” button.

Improvement 1 — a clear way back home — After — After

KEY STEP // 11

Improvement 2 — explaining rewards

On the Rewards History page, users struggled to understand how to earn and use reward points. We added screens that explain how the rewards system works.

Improvement 2 — explaining rewards — After — After

KEY STEP // 12

Improvement 3 — save from the list

Some users wanted to save charging stations directly from the list view instead of opening the details page. We added a “Save Station” action on the list.

Improvement 3 — save from the list — After — After

KEY STEP // 13

Prototype walk-through

Explore the clickable prototype to see how the app looks and works.

Open the Figma prototype

Results

Strong with EV owners — work to do for newcomers

EV owners rated the app far more usable and made significantly fewer errors. Drivers with little EV experience scored below 60, so the app has to work for new EV drivers too.

0SUS — EV ownersMean usability score among current EV owners.

0SUS — never driven an EVShowing where onboarding needs work.

0SUS — control groupHad driven an EV but did not own one.

0ParticipantsAcross three groups, five tasks each.

Strong with EV owners — work to do for newcomers — image 1

Learned from this project

The value of feedback: involving users at every step showed us which features they need and what causes frustration. We learned how EV drivers think, what challenges they face and what they expect from a charging app — easy payment options and better ways to find charging stations. By focusing on the main problems, like long wait times and confusing interfaces, we made a good start. Next steps: test with a wider group of people, refine the design using the feedback we already have, and prepare the project for the HFES conference.