You’re sitting in a terminal at JFK, or maybe a coffee shop in Berlin, and your laptop screen flickers with that dreaded 5% warning. You reach into your bag, pull out a brick that looks like it could stop a bullet, and suddenly, you’re the most powerful person in the room. That’s the vibe of owning an Anker big power bank.
But here’s the thing: "big" is a relative term that gets people into trouble. I’ve seen folks buy a massive battery only to have it confiscated at airport security because they didn't check the watt-hour math. Or they buy a "20,000mAh" unit that charges their MacBook at the speed of a dying snail.
Honestly, if you're looking for serious juice in 2026, you aren't just looking for capacity. You're looking for discharge rates that won't make you cry.
What "Big" Actually Means in 2026
Most people think "big" just means more milliamp-hours (mAh). That’s sort of right, but mostly wrong. The real metric you need to care about is the Watt-hour (Wh) rating.
Why? Because the TSA and every major airline globally have a hard ceiling at 100Wh.
If you go over that, you’re basically carrying a "dangerous good." Anker knows this. That’s why their heavy hitters—like the Anker Prime 27,650mAh (250W)—sit right at 99.54Wh. It’s the legal limit of "big." You get every single drop of power allowed by law without getting tackled by a security agent in a neon vest.
The Heavyweights: Anker 737 vs. Anker Prime 27K
If you want the absolute biggest portable chargers Anker makes that won't require a special permit to carry, you're looking at two specific models.
The Anker 737 (PowerCore 24K): This was the king for a while. It’s got that iconic smart display that tells you exactly how many watts are flowing and how long until it’s empty. It puts out 140W. That’s enough to fast-charge a 16-inch MacBook Pro while you're editing 4K video. It’s chunky. It’s basically a tall, dark, and handsome juice box.
The Anker Prime 27,650mAh (250W): This is the new gold standard. It’s slightly more refined and hits that 250W total output mark. You can charge three devices at once and still have enough overhead to keep a high-end gaming laptop from throttled performance. It also works with a magnetic charging base, so you don't even have to plug a cable into the bank itself to refill it.
The Myth of Capacity vs. Reality
I’ve had friends complain that their 20,000mAh bank didn't actually charge their 5,000mAh phone four times.
"I've been robbed," they say.
No, you’ve just met physics. Energy is lost as heat during the conversion process. Also, your power bank’s internal cells usually run at 3.7V, but your phone charges at 5V, 9V, or even 20V. When you factor in the efficiency loss—which is usually around 15-20% on a good day—that "big" battery starts looking a little smaller.
Anker is actually pretty decent about this. Their ActiveShield 2.0 tech monitors temperature 3 million times a day (according to their lab stats) to keep that energy transfer as efficient as possible. But don't expect 1:1 math. It just doesn't happen.
Anker Big Power Bank: Is the Prime Series Worth the Extra Cash?
The Prime series is expensive. We’re talking $150 to $180 for the top-tier models. You could buy three generic "big" power banks for that price.
So, why bother?
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Speed. Cheap big batteries are like a huge water tank with a tiny straw. It takes forever to fill up, and forever to pour out. Anker’s big banks support up to 140W input. If you have a beefy wall charger, you can refill that massive 27,650mAh cell from zero to 50% in about 25 minutes.
Think about that. You can top off your entire week's worth of phone juice in the time it takes to drink a latte. That’s the real "big" feature.
Who is this for?
- The Digital Nomad: If your "office" is a beach in Bali or a train through the Alps, you need the Anker 747 or the Prime 27K.
- The Steam Deck/ROG Ally Crew: Handheld PCs drink battery like it’s water. You need at least 65W output just to keep the battery level steady while playing.
- The "One Bag" Traveler: If you only want to carry one brick for your phone, watch, and laptop, this is the play.
The One Flaw Nobody Mentions
They are heavy. Like, actually heavy.
The Anker Prime 27K weighs about 1.45 pounds (665g). That doesn’t sound like much until it’s in your backpack for an eight-hour hike or a long day at a trade show. Your shoulders will feel it. It’s the trade-off. You’re carrying a literal power station in your pocket.
Also, that fancy screen on the Anker 737? It uses power. If you leave the "always-on" display setting active, it’ll drain about 15% of your battery in a day just by sitting there. Turn it off. It’s cool to look at, but don't let the UI eat your juice.
What to Look for When Buying
Don't just look for the highest number on the box. Check these three things:
- PD 3.1 Support: This is the protocol that allows for 140W+ charging. Without it, you’re stuck at 60W or 100W, which won't fast-charge the newest MacBooks or high-end Dell XPS laptops.
- Port Count: Make sure it has at least two USB-C ports. USB-A is basically a legacy port now. It’s fine for AirPods, but you want your main power coming through USB-C.
- The Recharging Speed: If the box says "Big Capacity" but only supports 18W input, run away. You’ll be charging it for 12 hours just to use it once.
Making the Most of Your Power
If you’ve just dropped $170 on a massive Anker bank, don't kill it in six months. Lithium-ion batteries hate being at 0% and 100%. If you aren't going on a trip, keep it stored at around 50-80%.
Also, keep it out of the sun. Heat is the number one killer of these high-density cells. If you’re at the beach, bury the power bank in your bag under a towel.
What You Should Do Next
If you need the absolute maximum power allowed on a plane, go buy the Anker Prime 27,650mAh Power Bank (250W). It is the peak of what's currently possible without breaking international aviation laws.
If you want something slightly more pocketable but still capable of charging a laptop, the Anker 737 is often on sale and offers 90% of the performance for a lot less money.
Check your laptop's maximum charging wattage before you buy. There's no point in paying for a 140W power bank if your laptop can only pull 45W. Save the weight and the cash.