Rivian Owner Charged 11 Hours and Only got 70 Miles On One Day, but 150 on Another Day Using the Same Home Charger. She Tries to Understand the Difference Despite The Scenarios Being Identical

Electric vehicle owners typically experience fluctuations in the the charging speeds, hence definite differences even when using the same charger. Rivian owner Georgeann Franks, shared an experience on the Electric Vehicles Discussion Facebook group indicating she had only gained 70 miles in 11 hours but twice that the next day. The post stated, 

Do I need to do something To prepare my battery to charge?  I charged at home last night and in 11 hours only got 70 miles. The other day I got 150 in  12 hours on the same charger. Trying to understand why the large differences?

Assuming this as the case, it disproves the notion that advertised charging time is only in optimal conditions. For one, the charging time is significantly below what is expected even for a home charger. Understanding why this happens also means looking into the equipment involved and environmental conditions.

Importance Battery Pre-Conditioning 

The conditioning significantly affects optimal  charging. When the battery is too cold or hot, it will not charge the way it should. Rivian models have a battery management system that regulates temperature so if the battery is not at the appropriate temperature when the charging begins, it can charge slower. Preconditioning can be done to warm or cool the battery according to the external temperatures. Activating preconditioning before plugging it in may reduce the overall charging time. 

Batteries also have a charging curve which means they do not charge at a constant rate to a 100%. When it is between 0 to 20%, it may accept a higher charging rate. However, if you begin charging at 50% the rate reduces. This may explain why Georgeann experienced different results from the same charger. If the battery was at a higher state of charge in one of the sessions, then it could have charged slower. 

External Temperatures may have Affected the Charging Rate 

Temperature also plays a significant role and was reiterated in the comment section. Michael Martin asked how the temperature compared from one session to another. She added that colder temperatures tend to decrease the charging rate so it would be advisable to check the schedule. Many current charging systems also allow one to set the charge times and integrate with home systems. That would allow the owner to see if there was a dip at some point. Georgeann replied that the temperatures were no colder the previous night than weeks ago.

In practicality, if the vehicle is left outside in freezing temperatures, the charging can take longer. This is because it needs more energy for it to reach optimal charging. Using a garage or preconditioning the battery will help in mitigating these effects. 

Potential Issues with Home Charging Setups 

Not every home setup is the same as there are differences in wiring, capacities and power fluctuations.If the other appliances are running at the same time, they can reduce the available power for charging. Similarly, older electrical systems experience many fluctuations which slow charging down. Steve White, on the thread commented to check the circuit breaker and to reset it. If it is 50A, then it might be partially tripped. Some home chargers also underperform  if they are not well installed so that may be what occurred. 

Rivian also updates the software frequently, to improve efficiency. Some updates tend to optimize the charging curves for different conditions. Ensuring the Rivian is running the latest software can sometimes help maintain the charging performance. 

To minimize the charging inconsistencies the owner can follow a few best practices. Preconditioning before charging is one way to go because it sets the right battery conditions. They may also start charging when the battery is low to benefit from the faster curve. The charging set up should also be double checked to ensure the Level 2 charger is appropriately installed and operating at the right efficiency. This variation in charging may be influenced by several factors from state of charge, battery conditions to external conditions. While some differences are the expectation, understanding them can help optimize the performance. 

Image source: RIVIAN Electric Vehicles Discussion Facebook Group and Grok AI

Nicholas Muhoro is an automotive journalist covering car news and has a decade of experience sharing working at HotCars and TopSpeed. You can follow Nicholas on X and on LinkedIn to stay in touch and follow his news coverage at Torque News.