Okay, I've been doing a lot of reading and researching... I think it's 70/30 that people recommends charge to 80% at home and 30% said 100% all the time.
I know some said because it's a lease, they do not care what the battery would be like in 8-15 years. Well, mine is a purchase and I plan on keeping this car for at least 10 years+
since it's a CPO and I do not know what the previous owner did, whats everyone's consensus on home charging to 80% vs 100%

 

It’s the one question that every new owner of a pre-owned EV asks themselves, and for good reason: "What did the last person do, and how much should I worry about it?" The internet is a minefield of paranoia on this topic, so let's cut through the noise and talk about what actually matters in the real world.

First, let's get our heads around why this is even a topic. Think of your battery’s health less like a gas tank and more like your own personal health. A single weekend of eating junk food won't ruin your long-term fitness, but making it a daily habit for years certainly will. Your battery is the same. Its longevity isn't about single events; it's about the consistency of its routine. A calm, steady routine keeps the battery's internal chemistry happy and slows down the natural aging process. That's why a consistent charging protocol is so important—it's the healthy lifestyle that ensures a long life.

Now, for the big one: can you play detective on the battery’s past? The straight answer is no. There's no secret menu in your car that gives you a detailed log of the previous owner's charging habits. Even a dealer can only tell you the battery's current overall health, not how it got there.

But here’s the more important answer: for the most part, it doesn’t matter. The engineers who designed your car knew people wouldn’t follow the rules perfectly. The battery's management system is like a silent, sleepless guardian, constantly working in the background to prevent the worst kinds of damage from heat and over-charging. For the previous owner to have truly hurt the battery, they would have needed to be almost maliciously negligent—like leaving it baking in the desert sun at 100% charge for months. The system is built to withstand normal, imperfect human behavior.

So, forget the past. Your ownership starts today, and your habits are what will shape the next decade of this battery’s life. Here’s the simple game plan—the stuff that really moves the needle:

1. Make 80% Your Daily Norm. Set it on your home charger or in the car and forget it. This is the single most powerful thing you can do for battery longevity. It's the equivalent of getting a good night's sleep, every night.
   
2. Treat DC Fast Chargers Like Road Trip Fuel. They are fantastic tools for traveling, but they’re a harder, more intense workout for your battery than gentle home charging. If you have the option, plug in at home for your daily needs.
   
3. Avoid Extremes for Long Storage. If you’re ever leaving the car for a few weeks, don’t leave it parked with a full 100% or a nearly empty battery. A middle-of-the-road charge (around 50-60%) is the perfect hibernation state.
   

That's really it. So much of the anxiety you read online is just stigma. If you occasionally charge to 100% for a weekend trip and forget to leave right away, or if you have to use a fast-charger a few times in one week, don't sweat it. That’s just life. You’re using a tool for its intended purpose.

Your new, healthy routine will be the defining factor in the battery's health. Focus on that, and you can let go of the worry about its mysterious past.

 

To add further, in most EVs 100% isn't actually 100% battery charge. Most EV batteries have a buffer. You don't get to use the full 100%. The EQS has about a 10% buffer, so when the car says it's 100%, in reality the battery is only 90% charged.

But in general, lithium batteries are designed to operate between 20% and 80% charge. So just like you don't wanna charge it over 80% constantly, you also don't want to discharge it below 20% constantly. So to the above points, even if you charge to a 100% regularly, it'll be fine. You can further aid it by not charging to 100%, so that you stay at or below 80% for your normal use. Charge to about 90%, then with the 10% buffer the battery is at about 80% effective charge and then charge before it reaches 10%.

This goes for all devices powered by lithium batteries. Smartphones and laptops have charging limits now just like EVs. For example I use my laptop mostly as a desktop, so it's always connected to the power supply and I'm using a 50% charge limit. Over the last 4 years, the battery has only lost 5% capacity. My iPhone is similar. I have the charge limit set to 80% as I don't need more on a typical day and then just temporarily raise it to 100% if I have an atypical day ahead of me. The idea is that you keep your battery healthy as long as you can, so that whenever you need 100% you still get 100% and not less.

 

You may be able to get a battery health report from your MB service center. Chances are it will be good, but the results should give you some peace of mind.

I have seen a video report of a Tesla courier in Australia that charged his vehicle to 100% every night for a few year with no negative effects and only minor battery degradation. No idea how the Tesla and MB battery and systems compare. If you follow the good advise above then your battery should last for the life of your car with minimal performance loss.

 

Those buffers are split between the top and bottom, with the bottom buffer being much larger.

10% total is not much. Follow the manufacturer suggestions and charge to 100% just before using it (e.g. road trips). Otherwise 80%.

You’d likely not ignore oil changes in an ICE to save money or for convenience. Personally, I want my EVs to last a long time for future owners.