Did charging to 100% for a few days actually damage my battery?
Two months in and I think I already messed up my battery permanently. Got home late last week, just plugged in and let it charge to 100% instead of stopping it early like I've seen people say you're supposed to, then didn't drive much for four days so it just sat there fully charged the whole time. Does that actually damage it for good or am I panicking over nothing? Also I still don't totally get the 80% thing — is that the same number for every EV or does it depend on the car?
Filed under: General EV Talk
48
15 answers
15 ANSWERS
@icewardenJuly 23, 2026
Eight years in, three different EVs, so I've done this dance more than once. First thing that actually matters: do you know if yours is NMC or LFP? Completely changes the answer. NMC — still most non-Tesla EVs and a lot of premium trims — you want to live around 80% day to day, charge to 100% only for a trip. LFP — a lot of base/standard-range trims now, including Tesla's default in the US — actually wants a full charge to 100% roughly once a week, doesn't wear the same way sitting high. One night at 100% because you were in a rush isn't going to show up as anything measurable on either chemistry. What actually matters is habit, not a single event — parking at 100% for days on end, or living down near empty for long stretches. Neither of those is what you described.
how do i even find out which one mine is, that wasn't on the window sticker as far as i remember
Usually listed in the manufacturer's app under battery or vehicle info, sometimes buried in the window sticker fine print, sometimes only in the owner's manual PDF. If none of those say it outright, base/entry trim on most 2023+ models defaulting to LFP is a reasonable first guess — but confirm it, don't assume off trim level alone.
Deep discharge damage isn't a one-time thing either — a single trip down near empty doesn't hurt anything. What actually accelerates wear is regularly parking under about 10% for extended periods, same mechanism as sitting at 100% for days: it's sustained time at either extreme, not a single dip or top-off.
Does the 80% guidance change at all if the car's mostly sitting versus actually being driven a lot between charges?
A little, yes, but it's about calendar time at rest more than driving frequency itself. The 80% guidance is really a daily-active-use number — car's getting driven, pack's cycling, you don't want it parked at either extreme for long stretches. If it's going to sit for weeks without much driving, like a seasonal storage situation, the better resting point is actually lower, somewhere around 50-60%, not 80% — high state of charge sitting idle for a long time is worse than the same high state of charge for a day or two while you're actually using the car. For normal use where you're driving it every few days, 80% is fine either way and you don't need to overthink adjusting it based on how much you're driving that particular week.
battery: sat at 100% for 4 days. also battery: still totally fine
The DC fast charging piece gets overstated in both directions in threads like this. Occasional fast charging, even weekly, isn't going to meaningfully accelerate wear on a modern pack with decent thermal management. What actually adds up over time is using DC fast charging as your primary daily method for months on end, especially back-to-back sessions on an already-warm pack. If you have any access to slower home or overnight charging, use that as the default and save fast charging for actual travel days.
Sitting at 100% for a few days isn't going to meaningfully age the pack on its own — the real degradation driver is time at high state of charge combined with heat, and a few days at normal temps isn't enough to move the needle. The 80% number also isn't universal — it comes from your manufacturer's buffer above the cell's true 100%, so it varies by pack and BMS. Worth checking your own car's manual instead of assuming your neighbor's number applies to you.
Worth pointing at the aggregate numbers here rather than just anecdote — Recurrent and Geotab have both published fleet-level degradation data across tens of thousands of vehicles at this point, and the spread by charging habit is smaller than forum threads make it sound. Most packs are still in the single-digit percent loss range after five years regardless of whether the owner babied the 80% rule or just plugged in and forgot about it. The real outliers in that data are daily fast-charging and sustained heat exposure, not the occasional full charge or a low state of charge for a day.
Logged every session since I bought mine — 260-some charges at this point. My own numbers back this up more than people expect: daily 90% home charges did basically nothing measurable over 18 months. The only dip I can actually attribute to a habit is a stretch last summer fast-charging most weekdays in the heat. Everything else is people repeating the 80% rule as gospel without ever pulling their own numbers to check it.
Data says it barely matters and I still keep mine around 80% out of habit. Can't undo degradation once it happens, so it's a cheap insurance policy even if the actual effect turns out to be small.
Is the 80% number actually standardized, or does every manufacturer set their own recommended ceiling for that pack chemistry?
@quietloomJuly 23, 2026
If I just leave it on the default and never touch the percentage, is that actually close to manually capping it at 80%, or is the default doing something different that I should know about?
No, don't assume that — on most non-Tesla EVs the factory default slider is set to 100%, not some baked-in 80% cap, unless you've actually gone in and moved it yourself. LFP cars are the exception since some of those ship recommending regular full charges rather than a limit at all. Actually open your charging settings and check what the number says rather than assuming 'default' means something conservative — plenty of people find out years in that they've been charging to 100% every night without realizing the slider was never touched.
Delete post?
Once you delete this post, it can't be restored.