Posts: 60
Joined: Thu Jul 13, 2017 8:19 am
Delivery Date: 21 Feb 2018
Leaf Number: 307105
Location: Greater Chicagoland

QC might improve SOH, maybe

Fri Mar 30, 2018 4:47 pm

I've always been skeptical that the increase in SOH caused by QuickCharging was real. But maybe high currents could melt fragile dendrites back into solid metal.
By applying a high-current pulse to a lithium-metal anode, the researchers were able to produce heat that wasn't enough to melt the lithium metal but was enough to encourage "extensive surface migration" of the lithium atoms. That essentially "healed" the lithium-metal anode of newly growing dendrites, which smoothed out the surface of the lithium anode again.

Not exactly the same phenomenon, but something similar, might be happening in LEAF batteries. I'd be the first to admit it's a long shot.

The research paper is behind a paywall. Ars Technica talks about the current density of a pulse but not its duration nor the temperature reached. There have been a lot of posts about battery degradation on MNL, but none that I know of discuss what chemical or mechanical changes cause it. In particular, I have no idea if there are dendrites in degraded LEAF batteries or even whether they have lithium metal anodes.

In a quirk of fate, one of the paper's authors has surname "Li".
2017-12-16 New Prius Prime
2018-02-21 Used 2015 LEAF SV Mfd 2014-07 In-service 2015-02-27
Date mi AHr SOH Hx QC L1/L2
2018-02-21 26,938 60.22 96.98% 90.73% 1 988
2018-07-01 31,601 58.05 93.48% 87.03% 11 1223
2018-10-01 35,428 55.63 89.58% 82.13% 16 1440

Posts: 950
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Re: QC might improve SOH, maybe

Tue May 29, 2018 12:57 pm

It does improve. I've noticed that. But SOH is just a number, not pure real life capacity.
I recommend QC once a month just to keep battery in shape :D
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

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