| vskid3 |
09-10-2017 02:09 AM |
Quote:
Originally Posted by BLSTIC
(Post 549531)
It would likely have software limited range in order to protect the batteries from continuous near-flat experiences. I don't know about lithium ion, but when a conventional lead acid battery goes low in charge the fluid gets less and less conductive, to the point of being basically water when you have a 0v battery. This is not good for the health of the battery.
But when it comes to the safety of the owner vs the health of the car, it's even a good marketing decision to allow your cars to 'sacrifice themselves' to reliably get the owners out of harms way in an emergency. I'm willing to bet there will be a *very* small failure rate from this one-off incident and Tesla looks like the good guys.
Oh wait, turns out the 60kw/h is software limited 75kw/h packs. odd... (I am now 100% convinced that if Tesla are doing this with battery packs that are known to be expensive, apple is doing this do iPhone memory (and memory is cheap)
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Lithium batteries don't really have a problem with being drained most or all the way like lead acid. They do benefit a bit from not using the top and bottom ends of the capacity, which is why most hybrids, PHEVs (Gen1 Volt uses ~10kwh of a ~16kwh battery), and some EVs limit the battery usage to the middle of the charge range. Most EVs utilize nearly the entire battery for maximum range, though. I would bet that most EV batteries rarely get run completely dry anyway just because that would suck for the driver.
The "60kwh" Model Ss with 75kwh batteries are the only ones that got the temporary capacity unlock. They were sold as a cheaper option to the 75kwh, but it must have been easier for Tesla to reduce the number of battery configurations and set the limit with software. I guess owners have the option to permanently unlock the extra 15kwh for a few grand. As a side effect, the "60kwh" batteries are expected to last a little longer, but that wasn't the motive for limiting them. There's quite a few high mileage Teslas without limited batteries that have suffered only minor battery degradation.
Computer CPU and GPU manufacturers do something similar where they test the chips then set parameters and assign model numbers based on how the chip performs. That means that a 6 core CPU that has 1 bad core can have 2 cores disabled and be sold as a quad core instead of being trashed. Depending on the chip and motherboard, sometimes that extra good core can be enabled. |
