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Comment by rconti | Hacker News Reader

I would guess they don't charge over 90% anyway.

I've only charged our 3 to 100% 5 or 10 times over 2.5 years. And I don't leave it sitting that way.

I've been shopping for a Bolt on and off for a couple months and you'd be surprised! I see folks all the time that say some dismissive equivalent of "oh it's a lease, I just charge to 100% every day". Not charging to full capacity will either become car knowledge that everyone learns in drivers ed or manufacturers will end up blocking off some percentage in software to prevent full charges.

Frankly I would prefer the software cap which I can disable (with a warning) for long trips. I like to plug in overnight and I can't check at 2 AM where the charge is at.

Yeah it makes no sense for the operator to manually regulate charging. We don't do that with any other rechargeable device. Oh gotta unplug my phone it's at 90%!

Exactly, the gas pump stops when the tank is full, not when its 10% overfilled.

First, every EV battery already has excess capacity you can't charge up.

Second, Nissan tried having the Leaf default to 85%. But they got in trouble for claiming more range than they should. The government rates the capacity in the default configuration.

There’s no reason you couldn’t have the default be 90% of whatever you thought was safe and allow 11% over rated on occasion by explicit user selection. It’d be like packing an extra gallon or two into your gas tank after the dispenser clicks off.

This was annoying because now my Leaf charges to 100% all the time, even when I never need to do that…

That's (basically) what the charge limit already does; nobody's running out to their car at 2am to unplug it before it hits 100%.

Presumably these "it's a lease" folks are just choosing to set the 'limit' at 100%.

I agree with other comments that I prefer the regen anyway; it's weird to charge to 100% and have to use the brakes to slow the car so much. Your efficiency on that last 10% of charge is lower because of this lack of regen.

The charge limit is not configurable on my car. Not sure about the Bolt or Teslas, though.

It's configurable on a Tesla.

Wait, if this is a known safety issue with batteries, why isn't there an engineered capacity head room? Set the max charge to the cells' 90% capacity, but report 100%.

It's a known long-term-battery-health issue. The catching-on-fire part is not normal.

That's what they already do. With lithium batteries neither 100% nor 0% are at the physical limits of the cell, they are both software limits. They might be enforced at the battery pack (over/undervoltage protection) or higher up in the chain.

It sounds like GM set the level too high, but it could also be something else like a problem in the battery's thermal management that is fixed by limiting the maximum charge level.

Tesla has a slider for the charge limit with 90%+ being designated as Trip and 50-90% as Daily. Even for a trip, I avoid charging above 90% because regenerative braking stops working when the battery is nearly full, which results in a substantial change to the way the car handles. You get used to one pedal driving and rarely having to use the brakes, so it's very unnerving for the car to not slow down rapidly when you let up on the accelerator pedal.

> I see folks all the time that say some dismissive equivalent of "oh it's a lease, I just charge to 100% every day"

Guilty as charged :). We charge our Model 3 to 80%. But my wife's Bolt is a lease, so we just left it at the default so it always has maximum range.

The Model 3 has a setting to do that. The Bolt does not. If you plug it in, it's charging to full.

With the Bolt, all you can do is use tricks like scheduling the charging late (so that it might not be fully charged by the time you drive off in the morning).

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