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What should my ideal charge percentage be?
- Thread starter Al Sherman
- Start date
Charging to 100% 2x a month whether you need it or not is just uninformed advise from an uninformed employee.
Generally you don't want to leave it above 90% for any length of time. Charging to 100% just before a trip is fine. I do it on every trip.
mknox
Well-Known Member
How does the resting SOC of the main pack have anything to do with the 12v system? The accessories will draw down the 12v battery, and the DC-DC will have to come on from time to time to top it up, but there is no relationship between this and the SOC of the main pack AFAIK.
gavine
Petrol Head turned EV Enthusiast
Perhaps at a low SOC, the system will be less "willing" to top-off the 12V (do it less often to conserve range), thus the assumption that a higher SOC on the traction battery will keep the 12v more topped-up? I don't know...just a guess.
mknox
Well-Known Member
The 12v load is so minuscule in comparison to the capacity of the main pack, it seems very unlikely Tesla would throttle 12v top-offs based on main pack SOC. Tesla does restrict remote HVAC control and Cabin Overheat Protection when the SOC falls below 20%, but since we're talking about where to set the slider, and it doesn't go below 50%, even if they did cut off 12v top-offs at 20% it wouldn't matter in the scenario being discussed here.
Sure was simpler back when I got my car. There were only 2 options: DAILY and TRIP. The consensus here was that DAILY was somewhere around 93% and TRIP was 100% with the same warnings about not using it too often.
I'll trust my Tesla service advisor's advice, who has been a close friend for many years prior to working at Tesla. Uninformed he is not. He sees these cars on a daily basis and has worked for Tesla for several years. He is the one who has been trained by Tesla and knows the car better than I do. If he tells me to charge my car to 100% twice a month whether I need to or not, I'm gonna do it.
My car is an MS85 and has 15000 miles on it and has not lost one mile in range since it was new. So there.
Veritas1980
Electric Viking
I'll trust my Tesla service advisor's advice, who has been a close friend for many years prior to working at Tesla. Uninformed he is not. He sees these cars on a daily basis and has worked for Tesla for several years. He is the one who has been trained by Tesla and knows the car better than I do. If he tells me to charge my car to 100% twice a month whether I need to or not, I'm gonna do it.
My car is an MS85 and has 15000 miles on it and has not lost one mile in range since it was new. So there.
Sorry, but if this has any merit, I should think they would include in the manual.
Also, I would assume others would get the same information from their Service Centers, but that seems not to be the case. Don't think it will do damage to the battery, but I bet it won't maintain it either.
I have a MS75, it has 12 000 miles on it, it has been charged to 100% twice in 7 months, no loss either.
It's bad info. Ask your friend to put it in writing on Tesla letterhead and I guarantee he won't do that. That should tell you something. Forewarned is forearmed. Good luck!!!I'll trust my Tesla service advisor's advice, who has been a close friend for many years prior to working at Tesla. Uninformed he is not. He sees these cars on a daily basis and has worked for Tesla for several years. He is the one who has been trained by Tesla and knows the car better than I do. If he tells me to charge my car to 100% twice a month whether I need to or not, I'm gonna do it.
My car is an MS85 and has 15000 miles on it and has not lost one mile in range since it was new. So there.
Edit: P.S. I will also guarantee you that your battery has degadation. Probably 2 or 3% YMMV or even more if you have been following the "charge to 100% twice a month whether you need to or not" advise.
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My undertanding is that at lower charge states the 12v won't pull from the main battery and the poster is talking about not plugging in and leaving the battery "empty-ish".
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Some Service Advisors will tell people to run the battery down below 20-30% and then charge to 100% occasionally to rebalance the battery algorithm. I personally do that but going outside what's in the manual could come back to bite you if there's a warranty issue.
FlatSix911
Porsche 918 Hybrid
Tesla battery expert recommends daily charging limit to optimize durability
Jeff Dahn, a renowned battery researcher and the leader of Tesla’s research partnership through his battery-research group at Dalhousie University, has been working on li-ion battery durability for Tesla for a year now.
One of those things is not charging to a full charge too often. Repeated full charges can arm li-ion battery cells, which is why Tesla recommends to only daily charge to 90% capacity and to charge to 100% only when needed for long trips. In the past, CEO Elon Musk even recommended 80% daily charging:
A Model X owner on TMC aims to keep his all-electric SUV for up to 20 years and he decided to reach to Dahn for advice on daily charging to optimize the battery pack longevity. The researcher responded: “I would recommend charging to 70% normally. When you need a long trip, charge to 100%.”
Jeff Dahn, a renowned battery researcher and the leader of Tesla’s research partnership through his battery-research group at Dalhousie University, has been working on li-ion battery durability for Tesla for a year now.
One of those things is not charging to a full charge too often. Repeated full charges can arm li-ion battery cells, which is why Tesla recommends to only daily charge to 90% capacity and to charge to 100% only when needed for long trips. In the past, CEO Elon Musk even recommended 80% daily charging:
A Model X owner on TMC aims to keep his all-electric SUV for up to 20 years and he decided to reach to Dahn for advice on daily charging to optimize the battery pack longevity. The researcher responded: “I would recommend charging to 70% normally. When you need a long trip, charge to 100%.”
FlatSix911
Porsche 918 Hybrid
I tried this for awhile. The results were not pretty. I was running down to about ~10% then supercharging to 90% once a week for about 2 months. During this period I was losing 1 Rated Mile (RM)/week. I've stopped doing that now (if it hurts, stop), and for the last couple of months I have not lost any RM. Now I charge using my UMC everyday. My daily commute takes me from 90% to 60%.
Whether it was dropping to 10% or the heat generated by supercharging from 10% to 90% I cannot say. I do think my 90 battery, with its different chemistry, also played a role.
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Going below 20% is perfectly fine. Even at 0% the battery still has about 4% left (I'm not making this up, the CAN bus shows that data). The only thing you want to avoid is hard acceleration and using full power at low battery levels. Other than that, discharging to a low level is fine. Just out of safety I would always aim to arrive at a charger at 10%. Unpredictable things happen so you always want a safety buffer.
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I recall that there was some evidence or theory that it was harmful to the battery to run so low. I thought being in the single digits was worse for the battery than being in the 90s. But afraid I can't recall the source of this.
I also thought someone also recently reported running out when he still had a a few percentage showing.
For these reasons I'm inclined to minimize the chance that I might have to run the battery deep into the single digits and also being caught having to make a long trip without a SC en route and not having sufficient charge.
This actually happened once when I had to take a pet to a 24 hour vet hospital that was far away, late at night and no SC en route. Luckily I had charged to 90% right away earlier that night -- rather than charging to only 70 or 80% or delaying the charge start until 2am. I try to keep the car charged to 90% all the time -- just in case. Lots of evidence that a regular 90% charge doesn't cause any significant degradation over long times.
ishareit
Member
This may or may not be relevant for Teslas... but I currently have a 2014 Nissan Leaf that I have charged to 100% pretty much *everyday* as a daily commuter. The charging timer is set to finish charging to 100% at 7am and I typically drive to work around 9-9:30 am and I come back home with about 40-50% charge remaining. After 45k miles, and 3 years and 3 months, there is *no* battery level drop. Nissan Leafs have 12 battery capacity bars and I still have all 12 bars on the dash. I don't have any other way to validate the capacity, but thought to share these stats.
Edit: About a dozen times during my ownership, I have also driven the car to almost empty.
Edit: About a dozen times during my ownership, I have also driven the car to almost empty.
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