Was approached by a friend with a Tesla this morning at the golf course. Of course, everything Tesla is better, in his eyes, and I should have bought one. However, he also informed me that my charging strategy was all wrong. He says the Elon Musk mantra is ABC, always be charging. He charges daily, is always hooked up to the home charger as soon as he gets home, charging daily to 90%. He says that is the correct way to do it. I would love to have a civil discussion about this concept, would love to hear what experienced members of this forum, especially those who have owned Tesla in the past, think about this charging strategy.

 

You can charge every day if you wish. MB recommends you charge to 80. The new Teslas have a new battery chemistry that likes to be full. Though Im not a battery engineer Im pretty sure that MB is beig extremely conservative with their battery recommendations. Its understandable this is their first gen and they want to meet their promises on longevity and so on. The enemy of battery longevity is heat, charging on a level 2 charger is a cakewalk for the battery even DC charging at 100kw or less is not a challenge thats why the eco charging level is 100kw. The car can charge at 100kw continuos at till 80& and 50kw to 95%. At that level it doesnt even use active cooling!
Im pretty sure you can charging at level 2 to 90% every night without any issue. The battery has around a 10% buffer that never gets used for that purpose. Ergo if you charge to 90 you still have 20% untapped. The battery is in effect 120kw the 108 is the "usable" battery.

 

It's interesting. I did google the owner's manual for his Tesla Model Y, and it clearly states that there is no advantage to letting the battery discharge more before charging, and that charging every night is recommended. This is not what most of us have been told, so I appreciate your comments about it. My only interest in this discussion is to learn what the best strategy is for maintaining battery longevity. If charging every day does not impact that, I will personally start charging a little more often. Would love to get more opinions.

 

What, specifically, does Mercedes Benz recommend for charging the EQS (and EQS SUV)? I find it disturbing that discussions in this forum about optimal charging strategy inevitably rely upon 'folklaw'. (Does anyone from MB follow this forum?)

 

As usual very few seem capable of reading the manual. Pages 195-196 of the on line manual give MB’s recommendations.

 

20 t0 80. Its been discussed to death. And its RTFM.

 

The manual also states to NOT keep the car plugged in all the time and only charge to near 100% if you are going to use the car immediately as going on a road trip.

 

Ford recommends ABC as well. Not only for the purpose of keeping the car charged but also because the car will always keep the battery at the optimal temperature when plugged in. Ford strongly recommends keeping the car plugged in during the winter months for battery temperature management.
I was somewhat surprised when MB did not have the same recommendation.
In the end there is nothing wrong with charging every night, but just don't go out of your way to charge every night if you don't have to. I have adopted a "charge when I feel like it" attitude for the EQS.

 

Yea....there is a fair amount of expertise on this forum, and I was hoping for some of the more experienced folks with engineering background to chime in with their educated opinions. I have read the manual, of both the EQS, and now the Tesla Model Y. Two very disparate instructions about charging. I have also been voraciously researching since my conversation, and most of the battery engineers agree that, while you can charge every night, it is not necessary. All agree on the 20% to 80% charging range, except for trips (except Tesla, which recommends 20% to 90%). One of the engineering publications I read stated that the Tesla recommendation was fine, except that it was unnecessarily more expensive for the user, and for the grid. I'm with Tjdehya. I'll follow the 20%-80% rule, and charge when it is convenient for me. I'd still love to hear educated opinions.....that can only benefit the forum population in the long run.

 

Correct on all points.
However, new Teslas are using new batteries which can be filled up to 100% as a preffered state.
Since Tesla uses their entire batteries without a buffer their previous 90% translates to 100% charge in the MB. I suspect that MB's 80% battery recommendation (which is 70% total capacity) is an extraordinarily conservative recommendation particularly using level 2 or level 3 chargers of 100kw or less.
I generally charge to 80 or 100 (depending of trip length) whenever I get under 40. On a long trip, I try to DC charge at 20 or below and juice up to 80 as fast as the charger will go.

 

Maybe go to Youtube and input Tesla Battery Degradation. On one of those Youtube hits, there's reference to a US Army study of Lithium batteries. Try that if you want to.

 

First owners of these EV’s should have no concern over battery longevity. It’s the second and third owners who might get caught with expensive replacements.

 

70% at ten years. Thats a pretty darned good warranty. I suspect the batteries will last a lot longer than that. If there is one thing Tesla has demonstrated is that batteries last a looong time. Much longer than anyone ever suspected. There are a lot of Teslas with way over 150k miles running on the original pack. The only manufacturer that has had issues with battery longevity has been Nissan and the reason has been well pinned down, no active battery cooling.
A mistake they have remedied on their new EVs.

 

I had a Tesla Model S P90DL for 6 years until July - now have an EQS 45-+

I was always encouraged by Tesla folk to charge to 90%

My main battery failed and was replaced after 2 years and it had dropped in range by 10 miles (vs 255 full range) - replaced under warranty

When I sold it 4 years later it had dropped by 15 miles (vs 255 full range)

I like charging my EQS to 80% and with the better overall range it's still better than 100% of my Tesla

My Model S had other issues
- Front near-side suspension collapsed while driving (not warranty)
- Rear motor degraded and got noisy and was replaced (warranty)
- Front lED running lights failed (common issue) and I replaced both costing me $3000 quivalent in pounds, and replacements started failing by time I sold car (neither covered by warranty)

 

Tesla has not been known for their reliability. The model X has been particularly bad.