I found Mr. Filch, Hogwarts’ ever-grumpy caretaker, hunched over a broken car key fob in the dungeon storeroom. A tiny silver disc glinted in his hand—no, not a Galleon, but a CR1620 battery.
“Useless thing,” he muttered, prying at the fob. “But if it fails, the Headmaster’s car won’t unlock, and I’ll be blamed. Again. You know what makes these work? This—” he held up the disc—“a 3V lithium coin cell, 16mm wide, 2.0mm thin. Slim as a Reducio charm, but tougher than a Protego shield.”
Intrigued, I sat. This wasn’t just a battery—it was a wizard’s secret. Let’s unmask its magic.
1. What Is a CR1620? (The Slim Sorcerer of Batteries)
The CR1620 is no ordinary coin cell. It’s a 3V lithium powerhouse—16mm wide, 2.0mm thin (thinner than a Parchment-Preserver spell), built for ultra-slim devices. Key specs:
- Capacity: 70mAh (perfect for low-drain magic, like car keys or glucose patches).
- Chemistry: Lithium manganese dioxide—leak-proof, like a Hermione Granger spell.
- Temp Range: -10°C to +60°C (survives frozen broomsticks and overheated cauldrons).
- Weight: 1.8g (lighter than a Chocolate Frog wrapper).
Real-World Hero: Powers 30% of modern car key fobs (Mazda, Peugeot) and medical wearables thinner than bandages. “Small, but everywhere,” Filch grumbled. “Like Mrs. Norris.”
2. CR1620 vs. Siblings: The Thickness Duel
Lithium coin cells have a family rivalry—thickness vs. stamina. Here’s how CR1620 stacks up:
- CR1620 (2.0mm): Slim champion. Best for car keys, fitness trackers, and devices that need to fit in pockets (or wand holsters).
- CR1632 (3.2mm): Bulkier, with 120mAh. For medical sensors (needs stamina, like a Hogwarts Express journey).
- CR1616 (1.6mm): Too thin! 50mAh, risky loose fit. For calculators (boring), not car keys (disaster).
Critical Insight: CR1616 is 0.4mm thinner than CR1620—like using a Shrinking Solution on a potion vial. It might fit, but it’ll wobble (and fail). CR1632 is 40% thicker, 42% more capacity—choose space vs. stamina, like picking between a Pocket Sneakoscope or a Deluminator.
3. Equivalents & Replacements: The Substitute Spells
Lost your CR1620? Don’t panic—some substitutes work… if you’re careful.
- DL1620: Perfect substitute. Same specs, different name (like Expelliarmus vs. Disarmament Charm).
- BR1620: Limited use. Lower drain, rare in devices (like Wingardium Leviosa—works, but not for heavy lifting).
- CR1632: Do not use. Too thick (3.2mm vs. 2.0mm). Like shoving a Firebolt into a Toy Broomstick holster—won’t fit.
Pro Tip: Emergency? CR2016 (2.0mm thick) might fit, but check voltage (both 3V). Like using Alohomora on a locked trunk—works, but risky.
4. Where to Buy: Hogwarts’ Battery Shops
Need a CR1620? Avoid dodgy Borgin and Burkes deals—stick to trusted spots.
- Local Stores:
- Pharmacies (CVS, Walgreens): Find them in the hearing aid section (where magic meets medicine).
- Electronics shops (Best Buy): Battery aisle, next to Nimbus 2000 remote controls.
- Auto stores (AutoZone): Key fob section (where Filch buys his).
- Online:
- Amazon: Panasonic CR1620 (5-pack for $4—cheaper than Fizzing Whizbees).
- Specialty sites (Ersaelectronics.com): For rare finds (like Gillyweed—but for batteries).
Red Flags: Gas station brands? 80% expired or fake (like Dungbombs labeled “perfume”).
5. How Long Does It Last? (The Magic of Stamina)
CR1620’s lifespan depends on use—like a Polyjuice Potion’s duration.
- Car Key Fob: 2-3 years. Low drain (10-15 button presses/day—like Accio for car keys).
- Fitness Tracker: 1-1.5 years. Constant Bluetooth/sensor drain (like Riddikulus on a Boggart—exhausting).
- Medical Wearables: 18-24 months. 24/7 monitoring (like Homenum Revelio—never sleeps).
Extend Lifespan: Store below 25°C. Heat drains lithium 30% faster (like Confringo on a chocolate bar—melts fast).
6. Global Magic: Beyond Car Keys
CR1620 isn’t just for Filch’s fobs—it’s everywhere, like Hogwarts ghosts.
- Automotive: Powers keyless entry (Mazda CX-5, Peugeot 208) and TPMS sensors (BMW tire trackers). “Even cars need magic,” Filch grumbled.
- Medical Tech: Dexcom G7 glucose patches (ultra-thin, like Invisibility Cloaks for monitors) and smart bandages (EU trials—tracks wounds like Scourgify for injuries).
- Consumer Electronics: Bluetooth trackers (Tile Slim—finds lost Time-Turners), LED jewelry (Van Cleef & Arpels pendants—glows like Lumos).
7. Why Engineers (and Wizards) Choose It
CR1620 isn’t flashy—it’s the Hermione of batteries: smart, reliable, and underrated.
- Space Efficiency: 2.0mm thickness fits devices where CR1632 fails (like Shrinking Spells for gadgets).
- Cost: $0.30/unit wholesale—cheaper than Pumpkin Pasties.
- Zero Leaks: Hermetic seal vs. alkaline’s “corrosion roulette” (no acid mess, unlike Dungbombs).
Roast Alert:
Alkaline coin cell (sniffing): “I’m $0.10 cheaper!”
CR1620 (dry, like Dumbledore): “I’m in your BMW. You’re in a dollar-store thermometer. Bye.”
The Future: CR1620 in 2030
What’s next for our slim sorcerer?
- AI Eyewear: Powers AR glasses thinner than sunglasses (like Muggle specs with Oculus Reparo magic).
- Mars Colony Gear: -40°C-rated variants for lunar keycards (NASA testing—because even Mars needs Alohomora).
- Eco Shift: USB-C rechargeable LIR1620 (1,000 cycles). “Reusable like Hogwarts’ house-elves—but cleaner,” Hermione noted.
The Secret of the Slim Powerhouse
CR1620 batteries aren’t in the spotlight. They don’t cast Expecto Patronum or brew Felix Felicis. But they’re why your car unlocks, your glucose patch works, and your LED necklace glows.
“Why so quiet?” I asked Filch, as he finally fixed the fob.
“Quiet things last,” he said, tucking the CR1620 back. “Like the Sorting Hat. Like Hogwarts. Like good batteries.”
And I realized—some magic isn’t in wands. It’s in the tiny, silent things that keep the world turning.
Written by a witch who once lost a car key fob… because she forgot to replace the CR1620. (Spoiler: Filch found it. And lectured her. For an hour.)
???? Some spells are loud. Some are just… reliable.