As EVs gradually transform the way we travel, energy storage is also entering more homes and power systems. The core of how we generate, store, and use energy has shifted toward batteries.

And once batteries become central to our daily lives, knowing how to use and take care of them becomes essential. But here’s the problem: Many people are still using old charging habits for a new battery chemistry. And that might be unnecessary — or even counterproductive.

The 20–80% Rule: Where It Came From

Four years ago, I bought an EV with an 80kWh NCM battery — the typical chemistry used in high-performance vehicles at the time.

Like many other NCM-based models, the manufacturer recommended:

• Keep daily charging between 20% and 80–90%
• Avoid charging to 100% regularly
• Don’t let the battery drop below 20%

This became known as the 20–80% golden rule. Why? Because NCM (Nickel Cobalt Manganese) batteries experience:

• Higher chemical stress at very high state of charge
• Faster degradation when kept at 100%
• Increased strain at very low charge levels

For NCM chemistry, this rule absolutely makes sense.
It’s practical. It works. And it helps maximize battery lifespan.

At that time, most EVs used NCM batteries — so this habit became deeply ingrained in users.

Then LFP Took Over

Shortly after EV adoption accelerated, battery technology evolved rapidly. More manufacturers began switching to LFP (Lithium Iron Phosphate) batteries.

Today:

• Over 95% of the energy storage sector uses LFP
• More than 60% of electric vehicles use LFP
• Market share continues to grow as the performance gap with NCM narrows

LFP is no longer the “budget option.” It has become mainstream.

And this is where things get interesting.

For LFP, the Old Rule Might Be Holding You Back

LFP chemistry is fundamentally different from NCM. It offers:

• A much more stable chemical structure
• Strong thermal stability
• A flat voltage curve
• Lower voltage stress, even at high state of charge

In simple terms:

LFP batteries are far more tolerant at 100% than NCM batteries.

In fact, something counterintuitive happens:

Regular charging to 100% can actually help.

Why?

Because it allows the Battery Management System (BMS) to:

• Recalibrate accurately
• Improve state-of-charge (SoC) estimation
• Unlock full usable capacity

That’s why many LFP user manuals recommend charging to 100% periodically.

Tesla, for example, even suggests charging LFP models to 100% daily.

That would have sounded almost “dangerous” in the NCM era.

But chemistry matters.

Daily Charging – Should You Go to 100%?

So what’s the right approach?

The honest answer is simple:

Follow your manufacturer’s guidance.

For most LFP users:

• 10–90% is perfectly fine for daily use
• Charging to 100% regularly is acceptable
• Charging to 100% occasionally is beneficial for calibration

Unlike NCM, you are not “hurting” the battery by reaching full charge under normal conditions.

LFP batteries are designed for frequent cycling.
They are built to be used.

Limiting yourself to 80% unnecessarily means you’re simply leaving usable energy on the table.

Fast Charging – Does It Hurt LFP?

This is another common concern.

Does DC fast charging damage LFP batteries?

It depends on system design — but generally, no.

Modern LFP systems use:

• Advanced thermal management
• Intelligent BMS control
• Controlled current curves

Occasional DC fast charging has almost no measurable impact on lifespan.
Even frequent fast charging causes only minimal additional degradation in well-designed systems.

Modern batteries are far tougher than most people think.

The fear often lingers from early-generation battery systems — but today’s packs are engineered differently.

What Actually Matters for LFP

Instead of obsessing over 80%, focus on what truly impacts longevity:

1. Use the capacity you paid for – Don’t limit to 80% without reason
2. Avoid extreme temperatures – Ideal charging range: 0–45°C
3. Don’t leave the battery at 0% for long periods
4. Follow your manufacturer’s app and manual guidance

Temperature management and proper system design matter more than avoiding 100%.

A Friendlier Era of Batteries

LFP marks a friendlier era for batteries.

They are:

• More forgiving
• Longer lasting
• More thermally stable
• Designed for real-world usage

By following manufacturer guidance — especially for popular LFP platforms like Tesla’s — you get:

• Accurate SoC readings
• Maximum usable energy
• Excellent long-term durability

Without unnecessary restrictions.

Stop worrying about “charging wrong” like in the older NCM days.

Battery chemistry has evolved.

Embrace the shift.
Charge confidently.
And let the technology deliver what it was designed to do.