Charging to 100% improves regenerative braking?!

[southerncadesi]

Can someone please explain to me how this is true? I would imagine the closer you are to 100% the harder it would be for the regen to charge up your battery.

This is from a Gen2 LFP

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[mikehmb]

It's almost certainly because the 100% charge will calibrate the BMS. You won't be able to regen at 100% (by definition), but will once you set off and use some of the energy.

 

[southerncadesi]

Gotcha, I understand why LFP’s need to be charged to 100%, but I didn’t know the BMS also aided the regen braking.

 

[Time2Roll]

Yes LFP tolerates 100% charge better than other chemistries. Charging to 100% allows the BMS to balance the cells properly on a regular basis. All systems work better with the cells in balance.

Otherwise yes the regenerative braking usually drops off as an EV is at or near 100% charge.

 

[ENVErider]

I also think it's a LFP calibration thing, I don't think I have ever seen this message on my phone go my NMC gen1. I did read an interesting article a few weeks ago about how Rivian deals with braking when battery bank is already full, say after filling up in the mountains and then doing one pedal driving sustained downhills. It makes sense that you'd be able to get closer to the true 100% with a recent calibration.

 

[UnsungZero_OldTimeAdMan]

Can someone please explain to me how this is true? I would imagine the closer you are to 100% the harder it would be for the regen to charge up your battery.

This is from a Gen2 LFP

No. It’s not about regen. It’s about maintaining software’s ability to gauge pack capacity (based on voltage) and provide accurate range estimation of cars with LFP packs. Watch Engineering Explained YouTube videos on LFP packs.

Regen is actually limited whenever pack is at or near 100%, to prevent cell damage. That’s why brake blending is needed to provide sufficient stopping ability. Charging to 100% occasionally recalibrates BMS, so it doesn’t think pack is near full when it actually isn’t (and falsely limit regen).

 

[southerncadesi]

No. It’s not about regen. It’s about maintaining software’s ability to gauge pack capacity (based on voltage) and provide accurate range estimation of cars with LFP packs. Watch Engineering Explained YouTube videos on LFP packs.

Regen is actually limited whenever pack is at or near 100%, to prevent cell damage. That’s why brake blending is needed to provide sufficient stopping ability. Charging to 100% occasionally recalibrates BMS, so it doesn’t think pack is near full when it actually isn’t (and falsely limit regen).

This makes sense, appreciate the explanation!

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