Range estimator calibration

[pieceofschmidt]

Gen 2 R1S dual standard just delivered on Monday. Got this text today (attached screen cap) telling me to plug in and charge to 100%. Well I only have 110 slow charger at home and the app says it’s been at 95% for most of the day today (started at 8pm last night) but the kWh keep going up - shows I’ve added 23.6 in 19 hours of charging. But it’s not moving mileage or % any more. Anyone have experience?

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[beatle]

My guess is that as the pack gets full, it continues to balance and bleed off excess capacity from the high modules. Even 240v and DCFC charging sessions get slow at high SoCs, but they're even slower on 120v.

Or maybe the truck is "seeing" a high SoC and is slowing down out of an abundance of caution, thinking the voltage spike at full will be there "any minute" but in reality it may actually be quite a ways off. LFP batteries can be kind of mysterious because of their flat voltage curve, so this is basically the charger operating in the dark.

How many kw does the app say the truck is charging at? Is it still ~1.4kw?

 

[pieceofschmidt]

My guess is that as the pack gets full, it continues to balance and bleed off excess capacity from the high modules. Even 240v and DCFC charging sessions get slow at high SoCs, but they're even slower on 120v.

Or maybe the truck is "seeing" a high SoC and is slowing down out of an abundance of caution, thinking the voltage spike at full will be there "any minute" but in reality it may actually be quite a ways off. LFP batteries can be kind of mysterious because of their flat voltage curve, so this is basically the charger operating in the dark.

How many kw does the app say the truck is charging at? Is it still ~1.4kw?

Yeah 1.3kw

 

[beatle]

I would not worry about it for a while. You're seeing 95% now, but the battery may actually be much less than that, and the BMS needs to see the voltage spike at the end to know that it is truly full.

You could try speeding it up a bit by putting it on a public L2 charger for a few hours, but it's likely to be full by tomorrow morning anyway and should then be calibrated.

 

[pieceofschmidt]

I would not worry about it for a while. You're seeing 95% now, but the battery may actually be much less than that, and the BMS needs to see the voltage spike at the end to know that it is truly full.

You could try speeding it up a bit by putting it on a public L2 charger for a few hours, but it's likely to be full by tomorrow morning anyway and should then be calibrated.

Thanks - I’ll just leave it overnight and not worry about it til the morning. I figured but just wanted to make sure I wasn’t just sitting on the charger for no reason. If it hasn’t resolved by tomorrow I’ll take it to a “real” charger haha.

 

[beatle]

Even if it stops overnight, there's no rush to remove the plug.

I'm not sure if this is your first EV, but leaving them plugged in is generally a good thing. LFP batteries are a little different. This is a good video talking about charging EVs with them and the voltage spike I mentioned:

 

[pieceofschmidt]

Even if it stops overnight, there's no rush to remove the plug.

I'm not sure if this is your first EV, but leaving them plugged in is generally a good thing. LFP batteries are a little different. This is a good video talking about charging EVs with them and the voltage spike I mentioned:

I’m coming from a Tesla. It’s not my first but I’m in a place now (condo) where it’s not super convenient to leave it plugged in all the time. I generally take it to a charger when I need - it’s my second car and my commute is about 5 miles per day 2 days a week haha so I’m not really putting many miles just dealing with vampire drain which I’m used to on the only Tesla as well.

 

[pieceofschmidt]

Update: left it plugged in to the slow charger and it “completed” but only read 99% so I took it to a Rivian Adventure Network charger this morning just to be safe and charged to 100%. Hope I’m calibrated!

 

[beatle]

Sounds like you're square now. I don't know if your Tesla ever stopped at 98-99%, but both of mine did occasionally when charging for a trip, though other times they had no problem making it all the way to 100%, even at home.

 

[pieceofschmidt]

Sounds like you're square now. I don't know if your Tesla ever stopped at 98-99%, but both of mine did occasionally when charging for a trip, though other times they had no problem making it all the way to 100%, even at home.

never had this problem but rarely charged the Tesla to 100 since that was a no-no for that battery type. Thanks for the help!

 

[beatle]

Just for anyone else's reference, you can still charge NMC batteries to 100% - it's just not recommended for daily use or for leaving it there for days. I routinely charged my Teslas and R1T with NMC batteries to 100% for road trips where I'll need to DCFC before I get there.

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