Is Frequent Supercharging Bad For A Tesla Battery?

Post date: 19-Apr-2020 10:05:12

Today i'm going to be talking to you about super charging Tesla's own proprietary DC quick charging technology as found on its Model S Model X and upcoming model 3 the fastest electric car charging technology available to the public today it's arguably one of the brand's unique selling points technically capable of providing up to 145 kilowatts of power although usually maxed out at 120 kilowatts in most cases Tesla's superchargers can replenish a compatible Tesla battery pack as a rate of just over 330 miles of range per hour about 540 km/h far faster than the 50 kilowatts currently used by both CHAdeMO and CCS quick charge.

Standards until recently Tesla gave customers with supercharger enabled cars unrestricted access to its supercharger network regardless of how many miles they drove or how old their car was but earlier this year that policy switched to only providing 400 kilowatt hours of free power per year for those buying brand-new Tesla's with Tesla then offering customers the chance to buy additional supercharger credits as and when needed that policy change caused quite a ruckus among Tesla fans but over the weekend another supercharger story surfaced which suggests that some owners especially those who use the supercharger network a lot but experiencing maximum charge rates during their cars supercharger session.

That were far lower than the superchargers theoretical maximum power why well in recent months Tesla has been working hard to discourage supercharger use for all but long-distance travel promoting destination charging and home-based charging as a more sensible solution for the vast majority of Tesla customers but in this case the reduction in supercharger speed for Tesla cars with a high supercharger use isn't a punishment it's a way to protect the batteries and thus ensure the car continues to operate properly for many more years to come as our friends over at electric.

We're told by Tesla earlier today every Tesla features an advanced battery management system that does everything it can to ensure the individual cells in each battery pack are kept in the best possible health to ensure high performance and longevity over many years of use just like any other electric car battery pack the lithium-ion cells found that a Tesla electric car slowly and inexorably aged with time this aging process not only affects how much electricity each cell can store but also the amount of instantaneous power an electric car can safely provide or receive and while modern lithium-ion electric car battery packs especially ones with adequate thermal management like Tesla's are designed to safely charge and discharge at high rates with a minimal effect on the battery pack.

Continued extreme charging and discharging does induce premature battery pack aging do it in a really warm weather and the effects are even more pronounced it's worth noting here that I'm talking about a use case outside normal electric vehicle ownership most plug-in car drivers charge at home overnight visiting a rapid charging station like a CCS CHAdeMO or Tesla supercharger when making the occasional long distance trip which is all well within the limits that most manufacturers plan for it's only when cars go through multiple rapid charging cycles day after day after day that the risk of damaging the battery pack increases if charged currents are kept high Tesla.

Just like every other automaker is well aware of this limitation rather than allow supercharger use cars to continue to charge at ultra high rates thus leading to premature battery death Tesla's engineers opted to add a subroutine which gradually limits the maximum supercharger power the car can use this routine does gradually lengthen the time it takes to charge the supercharger station maybe five minutes or so overall but it does so in order to protect the battery pack and ensure continued battery pack health for high supercharger cars I should note here too that I've seen the same thing happen with a Nissan Leaf owning an early 2011 Nissan Leaf myself for four years in the UK.

I can attest to the fact that as the car aged it had 82,000 miles on it when I sold it it charged more slowly as the number of miles in compared to when it was new I suspect that Nissan applied a similar algorithm to Tesla in order to protect its battery packs but I can't say this for sure but I digress in the case of this particular Tesla Model S owner who noticed that their car was super charging more slowly than it once was and took their car to be checked out at the local Tesla service center their car had accumulated more than 6.6 megawatt hours of DC quick charging sessions at CHAdeMO.

DC quick charges plus more than 50 supercharger sessions on top of this like my 2011 Nissan Leaf which used a today mode EC quick charging station far more frequently than the average Leaf this Model S and its usage patterns are certainly atypical for the average EV user indeed it puts this particular Tesla Model S into the 1% of cars the Tesla said are currently restricted in their super charging maximum power due to age mileage or number of supercharger sessions.

Most as I've said before shouldn't ever reach that point at least not for many many years but as the number of Tesla's in the wild increases the number of people who find themselves in that position will increase as well and while most Tesla customers understand why the supercharger limit exists some are vocally upset about it especially in the light of Tesla's recent patent applications pertaining to liquid cooling while charging as well as high high power super charging that could even double or triple today's supercharger speed to that.

However, I'll say this as battery charging speed increases so too does battery chemistry to make ever higher rates possible right now we're using a lithium-ion cell chemistry which has a limit on the number of times it can be charged at high voltage and high power before premature aging kicks in in five or ten years time will likely look back and laugh at how slow today's modern charging technology is by comparison to conclude it's only an extra five minutes or so per charge so ask yourself this would you rather have a car that takes a little longer to charge or one with the battery pack that's degraded to the point where you can't drive it very far anymore.