Scoring Methodology

How is the vsNEW score calculated?

vsNEW does 2 things - 1) show your battery’s current capacity, and 2) tell you if there are any warning signs of premature failure. Both of these factors go into your vsNEW score.

Our goal is to do this within 2 minutes, regardless of the temperature or charge level of the battery.

Battery capacity

The only perfect way of measuring a battery's capacity is coulomb counting, where you drain a battery and then slow charge it, counting how much energy goes into the battery, while keeping it at an optimal 70F temperature. However, this method takes between 8-24 hours and requires an EV to be plugged into a charger. Dealerships and most people aren't going to do this.

However, every OEM measures and tracks various metrics related to battery capacity for each of their vehicles and stores this information in the vehicle’s BMS (battery management system). Many OEMs use this value to determine if a battery should be replaced under warranty, which indicates how reliable OEMs consider this value is to be. vsNEW uses this same value to show your battery’s capacity.

Premature battery failure

The BMS also typically contains lots of additional data on your battery pack - 96 or more voltage sensors, 3 or more temperature sensors, a value for isolation resistance (which measures if the physical pack is damaged), counts of fast (DC) and normal charging cycles, incidents ofstorage at 100% or 0% charge levels, internal resistance values (which measures battery degradation on a per brick or module basis), and other metrics.

We use this data and leverage our database of thousands of similar vehicles to determine signs of premature battery failure. The most common signs of premature battery failure are uneven voltage levels and low isolation resistance levels.

How we get BMS data

By plugging into your vehicle, we read your BMS data within 2 minutes, upload your data into our cloud AI system, and generate a battery health report.

Common questions -

Why can’t I determine battery health by dividing the displayed range by battery charge level, and then divide by my original range?

Most OEMs vary the displayed range based on temperature and recent driving history. Called the guess-o-meter in these cases, the displayed range is unreliable as a measure of ideal range. In the case of Tesla, the displayed range is closer to an ideal range, but does not include reserve capacity and has been alleged to be unreliable at higher charge levels.

In our testing, this calculation’s error is between +5% and -20% of OEM measured capacity.

What about range reports that are based on telematics data?

Telematics data offers displayed range, charge level, and a few other metrics. We believe these reports are helpful to owners to track driving and charging habits, but the data is insufficient to determine battery capacity, premature battery failure, or battery health. Our testing shows the same error of +5% and -20% of OEM measured capacity.