Charging Habits

[brancky3]

I charge pretty much exclusively at work (free), which means I only charge Monday and Wednesday for about 4 hours each time. Charge limit is always at 85%. If I drive a lot on the weekends / etc I’ll charge at home but only to 70%. Gotta maximize the free charging! Of course, before road trips I charge at home to 100%.

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[CommodoreAmiga]

I charge pretty much exclusively at work (free), which means I only charge Monday and Wednesday for about 4 hours each time. Charge limit is always at 85%. If I drive a lot on the weekends / etc I’ll charge at home but only to 70%. Gotta maximize the free charging! Of course, before road trips I charge at home to 100%.

Do you actually NEED 100% to get to your destination or next charging stop? If not, stop charging to 100%.

 

[brancky3]

Do you actually NEED 100% to get to your destination or next charging stop? If not, stop charging to 100%.

With the vampire drain, yes normally. If I can’t leave my car without drain for 7 days at the airport (which takes 30-40% battery to get to) then I have to charge to 100% or go way out of the way to charge before coming home. We’re heading to Savannah GA in the spring for a weekend and I know I can make it to a charger on the way so I won’t charge to 100 in that case.

 

[Raghu]

Rivian home charger only gives 3-5 miles per hour
Any help is appreciated

 

[NY_Rob]

Rivian home charger only gives 3-5 miles per hour
Any help is appreciated

Are your referring to the 120V EVSE that is included for free w/the truck and plugs in to a standard wall outlet?

 

[srnyoung]

Another question - what if you just roll up to DCFC and “surprise” the T? As in, there is an EA along a route I travel regularly so wouldn’t otherwise use the map or set that as a destination? If I stop, R6g non what happens? Slower charge? Battery degradation? Anything?

 

[mikehmb]

It will charge to whatever level the computer thinks is safe for the temperature the battery is at when you show up. It’ll self-regulate. Might be optimal, might not. I’ve had mixed results, but every time I stop at a DC charger I’m planning to do something else anyway, and it’s -always- done charging before I am ready for it.

 

[the long way downunder]

Question: Does the rate of charge matter?

I don't drive much each day. I've scheduled my nightly charging to go up to 70% AND I've lowered the amps to 30. It is scheduled to start at 10p and finishes well before I wake up.

Does reducing the rate of charge help in anyway? Or is that just foolish / non-consequential?

While the difference in power and load between 30A and 48A is quite large … anything coming in contact with 250V at 18A is paying attention … it's relatively trivial compared to the 500A of the DC dispensers.

Personally, I "trickle" charge my EVs at 32A … I'm guessing I save about $11.42 per annum on heating the cabling and in transfer losses. : ) They're all on the same 100A sub-panel (all using Tesla HPWC which are meant to cooperate with each other for load sharing.) I don't think they've ever combined to trip that break, but the old 2018 Model X can draw 72A if it's feeling frisky, so I just dial them all back.

Also, I want the charging to finish right around 6:00am when the vehicles need to be ready. I don't want them to be "pre-conditioning" (using more energy to heat the battery) so I hope Rivian is quick to code "ready to depart at <time>" functionality. For now, I just let it start charging about 2:00am and four hours is usually enough.

Hardly scientific. If an EE or Rivian or Tesla came along said it's better to manage some particular charge curve or c-rate, I'd follow recommendations.

 

[Raghu]

Are your referring to the 120V EVSE that is included for free w/the truck and plugs in to a standard wall outlet?

No the home wall charger.
sleep mode fixed it. Put in sleep mode 30 minutes it starts giving 20 miles perhour. Rivian support helped

 

[Thedude]

Do you actually NEED 100% to get to your destination or next charging stop? If not, stop charging to 100%.

Charging to 100% is not a problem or bad for the battery pack. Leaving it sitting at 100% for extended periods is what is bad.

 

[WSea]

Do you actually NEED 100% to get to your destination or next charging stop? If not, stop charging to 100%.

Why not? I see no issues charging to 100 just prior to leaving on a road trip. Nice to stretch that first leg of a multiple charging stop trip. Last roadtrip we did seattle to Salem for first charging stop…almost 4.5 hours

 

[hayduke]

If you’re plugged in this is kind of irrelevant. You tell the Rivian to precondition the cabin, it draws from the battery to do it and automatically starts charging again at the same time.

not sure it’s irrelevant. i’d be surprised if any j1772 vehicle could reliably use shore power to heat the cabin. the minimum charge current j1772 allows is 6a (around 1500 watts) and whether it will initiate charging is dependent on SOC, charge schedule (as mentioned), and once charging initiates it will also follow the charge rate set by the evse not the amount needed by the heater.

these are all big practical differences if you’re trying to avoid wear cycling the battery by charging or discharging it for heating.

teslas feature sounds neat, but i don’t think j1772 has anything like that. tbh it’s pretty primitive protocol. the evse doesn’t even know the soc of the battery for example. it’s fairly limited in what smarts it can provide.

sure over time rivian’s charger might get smarter with software updates but for now it’s pretty basic. dumb thing i saw it do this week: had the battery at 71% when i plugged it in (set to charge to 70). it sat all day parasitically drawing power down to 69 or 68. then it decided it needed to start charging (probably needing to precondition the battery too). but this was maybe 15 minutes before peak pricing / my charging schedule window ends. ofc it didn’t get to 70 in those 15 minutes as i think it mostly was heating the pack. then it ends at 69 and says it will continue the charge tomorrow (and probably have to heat the pack even more by then).

charging also has a several hundred watt overhead so charging at very slow speeds (12a or less) might fool you into thinking it’s more efficient due to lower i2r losses or whatever but it’s likely actually using more kwh to charge your pack due to having to run the charger that much longer.

 

[Thedude]

not sure it’s irrelevant. i’d be surprised if any j1772 vehicle could reliably use shore power to heat the cabin. the minimum charge current j1772 allows is 6a (around 1500 watts) and whether it will initiate charging is dependent on SOC, charge schedule (as mentioned), and once charging initiates it will also follow the charge rate set by the evse not the amount needed by the heater.

these are all big practical differences if you’re trying to avoid wear cycling the battery by charging or discharging it for heating.

teslas feature sounds neat, but i don’t think j1772 has anything like that. tbh it’s pretty primitive protocol. the evse doesn’t even know the soc of the battery for example. it’s fairly limited in what smarts it can provide.

sure over time rivian’s charger might get smarter with software updates but for now it’s pretty basic. dumb thing i saw it do this week: had the battery at 71% when i plugged it in (set to charge to 70). it sat all day parasitically drawing power down to 69 or 68. then it decided it needed to start charging (probably needing to precondition the battery too). but this was maybe 15 minutes before peak pricing / my charging schedule window ends. ofc it didn’t get to 70 in those 15 minutes as i think it mostly was heating the pack. then it ends at 69 and says it will continue the charge tomorrow (and probably have to heat the pack even more by then).

charging also has a several hundred watt overhead so charging at very slow speeds (12a or less) might fool you into thinking it’s more efficient due to lower i2r losses or whatever but it’s likely actually using more kwh to charge your pack due to having to run the charger that much longer.

I don’t use any charge schedule so my experience might differ. When plugged in my truck will sit there at the limit and start/stop charging as needed to maintain the limit. If I turn on the cabin, seat and wheel heat it will draw on the battery for a little bit before the charger kicks back in and begins pulling AC power to replenish the battery back to the preset limit.

 

[CommodoreAmiga]

not sure it’s irrelevant. i’d be surprised if any j1772 vehicle could reliably use shore power to heat the cabin. the minimum charge current j1772 allows is 6a (around 1500 watts) and whether it will initiate charging is dependent on SOC, charge schedule (as mentioned), and once charging initiates it will also follow the charge rate set by the evse not the amount needed by the heater.

these are all big practical differences if you’re trying to avoid wear cycling the battery by charging or discharging it for heating.

teslas feature sounds neat, but i don’t think j1772 has anything like that. tbh it’s pretty primitive protocol. the evse doesn’t even know the soc of the battery for example. it’s fairly limited in what smarts it can provide.

sure over time rivian’s charger might get smarter with software updates but for now it’s pretty basic. dumb thing i saw it do this week: had the battery at 71% when i plugged it in (set to charge to 70). it sat all day parasitically drawing power down to 69 or 68. then it decided it needed to start charging (probably needing to precondition the battery too). but this was maybe 15 minutes before peak pricing / my charging schedule window ends. ofc it didn’t get to 70 in those 15 minutes as i think it mostly was heating the pack. then it ends at 69 and says it will continue the charge tomorrow (and probably have to heat the pack even more by then).

charging also has a several hundred watt overhead so charging at very slow speeds (12a or less) might fool you into thinking it’s more efficient due to lower i2r losses or whatever but it’s likely actually using more kwh to charge your pack due to having to run the charger that much longer.

the car doesn’t have to take/use all the current the EVSE “advertises”. The vehicle can connect to a 48A @ 240V capable EVSE and decide to only pull 500W if it wants. The EVSE simply sets the limit/cap — the vehicle chooses how much power to take.

 

[Trandall]

The Rivian is my 1st full EV as well so I did plenty of reading while I waited for a few years, haha. To keep it simple I would say there seems to be very little difference for battery health whether you charge nightly to 70% or twice a week from a lower SOC up to 70%. Charging to 100% or DC fast charging is not a big deal if you need to do it a few times a month I would not hesitate, it's if your routine was to do it 200-300 times a year that would be problematic. At the end of the day we are talking about battery longevity that should last 300K+ miles if treated well vs 200K+ miles if pushed hard (Full disclosure I am ballparking these numbers) so unless you are someone who stressed about how many minutes your ICE engine was running there's no reason to stress about this.

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