Most power banks die a wasteful death. The cells inside fade, and the charging electronics, ports and shell — all still perfectly functional — end up in a drawer. ZERO, a modular external battery from Paris-based CTRL ENERGY, is designed to prevent exactly that. Rather than sealing its energy storage away, it hides six standard cylindrical cells behind a magnet-fastened lid, letting owners replace the ageing parts themselves. The project opened on Kickstarter on 13 October 2026 under the “Meet ZERO” campaign, and within two days it had already blown past its all-or-nothing funding target.
- Replaceable core: six standard 18650 lithium-ion cells at 3,500 mAh each, removable without tools thanks to a magnetic lid and pull tab.
- Genuine power: up to 100 W USB-C Power Delivery in and out, plus 18 W USB-A Quick Charge 3.0 and 15 W magnetic wireless charging.
- Aggressive pricing: $89 early-bird on Kickstarter against an expected $128 retail, while the smaller SubZERO starts at $39.
- Unresolved risks: CE, RoHS and UN 38.3 certifications are still pending, and first deliveries are not scheduled until June 2027.
What owners can actually swap
The lid is held by magnets, so it lifts off without a screwdriver, exposing six cylindrical 18650 cells rated at 3,500 mAh apiece. They are wired in a three-series, two-parallel layout, delivering roughly 11.1 V nominal and 77.4 Wh — the same energy expressed as about 21,000 mAh at the 3.7 V reference conventionally used for portable batteries. Nothing is soldered or glued in place, so the cells are genuinely user-serviceable.
CTRL ENERGY has validated three specific models: the Samsung INR18650-35E, the LG INR18650-MJ1 and the Molicel INR18650-M35A. The company asks owners to change all six at once and to stick to a single model, which is sound practice: mixing cells with different wear levels inside one pack invites uneven behaviour and safety headaches. A QR code inside the lid points to the brand’s own spares channel, although these cells sell online for only a few dollars each — the central economic argument for the design.
On the safety side, a battery management system watches for overcharging, deep discharge, overcurrent, short circuits and excessive temperature. CE marking, RoHS compliance and UN 38.3 transport testing are all planned rather than achieved, with testing penciled in for the first quarter of 2027.
Ports, accessories and expansion
As a charger in its own right, ZERO is a high-end proposition: USB-C Power Delivery up to 100 W in both directions, a USB-A port running Quick Charge 3.0 at up to 18 W, and magnetic wireless charging at up to 15 W. That is enough for smartphones, tablets, cameras and laptops that accept USB-C power. The charging ports sit on a separate, detachable module, and a magnetic interface along the side accepts add-ons — a flashlight, additional USB outputs, a panel light or a face-tracking tripod.
The body measures roughly 166 x 88 x 28 mm, and up to five units can be linked into a single block with more than 105,000 mAh on tap. A smaller sibling, SubZERO, uses one replaceable 5,000 mAh 21700 cell with USB-C charging at up to 20 W. CTRL ENERGY says the enclosure is 3D printed from recycled ABS, and it has begun publishing selected accessory designs — a cable winder and a stand — under a Creative Commons Attribution-ShareAlike licence. It is worth being precise here: the electronics, firmware and manufacturing files remain unpublished, so ZERO should not be described as open-source hardware.
Pricing, timing and the crowdfunding gamble
Kickstarter backers pay $89 for ZERO against a planned retail price of $128, while SubZERO is listed at $39 versus $56. European prices include VAT, and buyers outside the EU settle duties and taxes when the parcel arrives. The campaign sought €9,986 and by the afternoon of 15 October stood at 161% of that figure with 28 days still to run. Production is meant to begin in the second quarter of 2027, with first shipments targeted for June 2027. Warranty coverage is one year, extendable to two if a corresponding stretch goal is met, although EU consumers keep a two-year legal guarantee regardless.
The caveats are the familiar ones for crowdfunded hardware. Certifications are outstanding, final electrical specifications are still to be locked in before mass production, and any slippage pushes delivery further out. The product site also leans on assertions it does not substantiate, such as the “highest repairability score in its category” without naming the scale involved. The concept is not a first either: earlier Kickstarter projects have fielded swappable-cell power banks, including one with two removable 21700 cells at roughly $36 and a maximum output of 22.5 W, and another capped at 30 W. ZERO’s advantage is the gulf in output, not the idea itself.
The design instinct is right, and it aligns with the direction European battery rules have been pushing for years. Making the wear item a cheap, standard 18650 cell rather than a proprietary pack is what turns repairability from marketing copy into something real. The sprawling accessory ecosystem, by contrast, feels like campaign theatre. For anyone who simply wants a battery that outlives a three-year cycle, the decisive question is whether CTRL ENERGY will still be around to sell spare cells and lids when they are needed — and no 30-day campaign can answer that.
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