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Comment by jve | Hacker News Reader

>This created a lot of confusion among the owners affected by the update who wanted more details about the sudden need to “protect” the battery pack.

They would surely complain if Tesla didn't include any "protections" while charging battery (80% capacity by default, slower charge when capacity approaching full, managing battery temperature, etc.)

But can someone explain why some update for charging protections affect mileage? I can understand if they compare capacity per constant time charged and telling us that after x hour charge I could do x miles, but now x-y... but if trying to charge full...? Maybe Tesla just reserves some capacity for longer lifespan of batteries?

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> They would surely complain if Tesla didn't include any "protections" while charging battery

Every li-ion battery needs protection, but there's a world of difference between a performance reduction present before sale and one added after sale.

If you pay for a Porsche Boxster, they can't remotely reduce the performance to that of a Toyota Prius, no matter how good that may be for the longevity, safety and emissions.

There's a pretty detailed breakdown available on some of the issues with packs from the affected models and years: https://skie.net/skynet/projects/tesla/view_post/23_Explaini...

Basically there are issues with the BMS that could cause an issue at higher states of charge. They shipped firmware to limit the charge until they could sort out the cause and potentially fix it with software. And it sounds like that part is resolved in many cases.

It looks like the charging issues are different, and he didn't go into those. Anecdotally, I've been hearing a lot of reports of that getting fixed too, though.

The writeup is brilliant, and the engineers have certainly done heroics to find a software fix for an issue that should warranted a recall.

But that doesn't exonerate Tesla in any way. Tens of thousands of customers got cars gimped with no official explanation from Tesla. It's been close to two years - that's a significant part of the vehicle's lifetime. Tesla still hasn't admitted any issues and still hasn't compensated the owners - absolute radio silence from them. It's abhorrent

It's very common to avoid discharging the batteries fully as it has a disproportionate affect on the life of the battery. So this update likely not only changed the rate at which the battery charged to protect it but also raised the minimum charge of the battery needed to drive - thus reducing the range.

The last part is one thing that occurred to me. I rented a Model X recently via Turo and struggled for an entire day with the car operating at <20 miles of indicated range (due to the long trip to pick it up + no local charging options above 7kW).

At the time I wondered if there was 'reserve' range and turns out there is at least one mile left. But it's clear this isn't the healthiest range to run the battery in.

It's possible they bumped the minimum charge a bit just to urge people to not dip so deeply into the well as often.

It's a default judgment, so it doesn't mean much.

It does seem like Tesla realized that the current fast charging + 100% utilization was going to be negative to customer experience quickly (battery degradation) and adapted their charging speed+spare, but they provided no information or guidance to users.

This sounds the same as the Apple situation. In both cases, simply providing appropriate information for users would likely have resolved the whole issue. But they did it quietly and let it be a surprise.

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