General Charging Questions

[paranee2]

I am hearing different stories about charging the battery. So, there are so many people like me having similar questions. Here are some of the questions. Experts, kindly reply with simple explanations.

1. What is the best level to charge the battery daily?

2. Is charging daily okay, even to 70-80%?

3. Is charging frequently at a DC charger okay?

4. I am hearing another story: charging up to 70 or 80% is recommended for DC chargers, not for Level 2 (home chargers). For Level 2 chargers, we can charge up to 100% because the slow charge won’t affect the battery as much. The reason is that DC chargers overheat the battery, therefore it’s better to limit charging to 70-80%.

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[HaveBlue]

Lithium batteries don't like being overcharged, over discharged and over heated. DC charging runs a higher risk of over charging a cell in the pack because balancing isn't always perfect. This is why charging past 80% really slows. On the road you are better off moving along. Over charge balancing is less likely at level 2 speeds as is overheating. If you don't need the range, it's recommended to save full charges for when you need them.

 

[RivianPVE]

I am hearing different stories about charging the battery. So, there are so many people like me having similar questions. Here are some of the questions. Experts, kindly reply with simple explanations.

1. What is the best level to charge the battery daily?

2. Is charging daily okay, even to 70-80%?

3. Is charging frequently at a DC charger okay?

4. I am hearing another story: charging up to 70 or 80% is recommended for DC chargers, not for Level 2 (home chargers). For Level 2 chargers, we can charge up to 100% because the slow charge won’t affect the battery as much. The reason is that DC chargers overheat the battery, therefore it’s better to limit charging to 70-80%.

Hi! I’ve owned 5 EVs to date and here are my 2 cents:

1. 80 to 90% daily is fine and will not affect longevity of the battery
2. Daily to 90% is fine
3. Frequent charging at DC chargers will not degrade your battery appreciably more than level 2 charging at home
4. Regardless of DC fast charge or level 2 charge, you should not charge over 90% if you don’t want to see excessive degradation of the battery. If your car had the LFP battery, then a 100% charge would be fine but our cars have the lithium-ion which should not be fully charged all the time. 20 to 80% is the best range for the battery (although Tesla has always recommended up to 90% and I’ve always charged all my cars to 90).

 

[Treebeard]

I am hearing different stories about charging the battery. So, there are so many people like me having similar questions. Here are some of the questions. Experts, kindly reply with simple explanations.

1. What is the best level to charge the battery daily?

2. Is charging daily okay, even to 70-80%?

3. Is charging frequently at a DC charger okay?

4. I am hearing another story: charging up to 70 or 80% is recommended for DC chargers, not for Level 2 (home chargers). For Level 2 chargers, we can charge up to 100% because the slow charge won’t affect the battery as much. The reason is that DC chargers overheat the battery, therefore it’s better to limit charging to 70-80%.

The charge settings screen has recommendations as well. It will tell you daily driving set to 70%.

 

[Sagesq]

I am hearing different stories about charging the battery. So, there are so many people like me having similar questions. Here are some of the questions. Experts, kindly reply with simple explanations.

1. What is the best level to charge the battery daily?

2. Is charging daily okay, even to 70-80%?

3. Is charging frequently at a DC charger okay?

4. I am hearing another story: charging up to 70 or 80% is recommended for DC chargers, not for Level 2 (home chargers). For Level 2 chargers, we can charge up to 100% because the slow charge won’t affect the battery as much. The reason is that DC chargers overheat the battery, therefore it’s better to limit charging to 70-80%.

I’ve charged to 85% since the day I purchased it. I have the max battery pack, and frankly, I don’t wanna run out of miles anywhere, and I highly doubt there’s any battery issues with this type of technology. Plus, I doubt you’re gonna keep this car for 10 years.

 

[Trandall]

@paranee2 Rivian recommends a daily charge limit of 70% for optimal battery longevity. If 70% range is sufficient for your daily needs that's best practice. If you need more, charge to a level that fits as needed. Reality is the battery is warrantied regardless of charging patterns. Personally I charge daily to 70% and more as needed. For long trips requiring DC fast charge stops I still only charge at home to 95% unless 100% would make the difference between having an extra stop and not which is an edge case I've never encountered. It's true that DC fast charging is a little harder on the batteries than L2 charging but Rivian has a fairly conservative charge curve and the battery degradation delta should be minimal. I see you live in Canada so I would recommend daily charging when temperatures are approaching or below freezing just so you start out with a warmer battery. Simple answer is Charge as needed allowing reasonable range buffer enjoy your Rivian and don't fret about battery longevity the relatively short reporting period we have shows them holding up quite well.

 

[Dirtman16]

Others have basically said this, but you really only need to keep 2 rules in mind.

1) Don't let the battery sit for extended periods at very high (>90) or low (<10) states of charge. Even better if you can keep it closer to 50%. If you need to charge high, just make sure you're driving it soon after. If you're low, make sure to charge it as soon as you can.
2) Rule 1 is MUCH more important for high states of charge when it's hot. The worst degradation will happen at very high states of charge when battery temperatures are high.

 

[Dave Cundiff]

Others have basically said this, but you really only need to keep 2 rules in mind.

1) Don't let the battery sit for extended periods at very high (>90) or low (<10) states of charge. Even better if you can keep it closer to 50%. If you need to charge high, just make sure you're driving it soon after. If you're low, make sure to charge it as soon as you can.
2) Rule 1 is MUCH more important for high states of charge when it's hot. The worst degradation will happen at very high states of charge when battery temperatures are high.

My reading suggests that @Dirtman16 has it about right. Most non-LFP vehicle batteries seem to prefer charge states around 50%, especially when it's hot.

My use case is a ten-mile round trip to work, plus occasional round trips of 90-320 miles that are usually predictable. We have public power, not a for-profit power company, and our marginal cost at home is $0.062 (6.2 cents) per kWh. So our home power costs much less than commercial charging, even at typical Level 2 prices.

My practice is to let the battery decrease to 40-45%, unless a longer trip is planned. Then we charge to 55%, or until half the next day's estimated consumption will take it to 50%, whichever calculation leads to a higher charge..

So, if I'm preparing for a 240-mile round trip (about 104 kWh, or 73% of a MaxPack), and prefer not to charge on the road, I charge to about 87% and expect to return at about 14%. That keeps the average as close to 50% as possible, while making the vehicle as useful as possible.

If I do this calculation often enough, it becomes mostly intuitive. That being said, not everyone wants to run calculations all the time. You should be adept enough at EV arithmetic to avoid catastrophe, but anything beyond that is a personal preference. Simply put: You should control the vehicle. The vehicle shouldn't control you.

I hope this helps!

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