Daniel's latest one lands somewhere between a philosophy essay and a very specific hardware fantasy. He's been living out of a personal carry system for months now, moving between apartments, and the thing that struck him is that once you get the pouches and the biomechanics right, your body becomes the office. You don't need a desk. You need a way to have whatever you need on you at all times. And he's whittled the list down to almost nothing. Phone, power bank, maybe a flashlight, medication, keys. Two admin pouches. Done.
And then the charger dies.
And then the charger dies. That's the whole thing. The one component that's most likely to fail is the one everything else depends on. No phone means no maps, no payment, no contact, no remote work. And the power banks he's tried all run out surprisingly fast, degrade quickly, and only work if you remember to top them up every single day. So he's asking whether anyone has actually engineered a real solution, or whether the market is still stuck selling small-capacity individual bricks.
His proposed solution is the part I want to sit with. Six lighter units wired together instead of one big one. A cascading charge flow, one device powering the next, with a logical controller sitting on top to monitor the whole distributed system and manage charge and discharge intelligently. He's describing a wearable power grid.
And he's asking if it's crazy or just early. So today we're going to take Daniel's slightly crazy idea and see if it's actually crazy, or if the engineering already exists and the market just hasn't caught up.
The engineering exists.
I had a feeling you were going to say that.
We'll get there. But first I want to talk about why the idea even makes sense at the level of the carry system itself, because that's the part most people skip. Daniel's framing is that the personal carry system is a philosophy as much as a product category. The shift isn't just from a bag to a belt. It's from a fixed location to a mobile platform. Your body is the infrastructure. And once you accept that, the question changes from what do I need at my desk to what do I need on my person, and the list shrinks fast.
It's the same thing that happens when you pack for a trip. You start with the big suitcase and by the third day you're carrying a pouch with three things in it because you learned what you actually touch. The carry system just formalizes that discovery.
Right, and there's a feedback loop with the biomechanics. You can't carry forty pounds on a belt without wrecking your lower back. So the weight limit forces the prioritization. Phone, power, keys, meds, light. That's the core. Everything else is optional. And the power is the interesting one because it's the only item on that list that has a runtime.
Keys don't discharge. Medication doesn't need a top-up. The flashlight might, but a decent one runs for months on a charge. The power bank is the only thing in the pouch that you have to actively maintain, and it's the one with the shortest lifespan.
And the least honest marketing. Let's just get the capacity thing out of the way first, because it's the foundation of why Daniel's frustration is legitimate. A power bank rated at ten thousand milliamp hours does not deliver ten thousand milliamp hours to your phone. The cell inside might be three point seven volts nominal, but the output to your phone is five volts, sometimes nine or twelve for fast charging. That voltage conversion loses energy as heat. Then there's the charge controller's own consumption, the cable resistance, and the fact that the phone's own charging circuit is also not perfectly efficient. Real world, you're looking at sixty to seventy percent of the rated capacity actually making it into the phone's battery.
So a ten thousand milliamp hour brick is really a six thousand milliamp hour brick wearing a nice label.
And a twenty thousand milliamp hour brick is really more like twelve or thirteen thousand. Which is still a lot. But here's the thing. A twenty thousand milliamp hour power bank weighs around four hundred grams. That's nearly a pound. It's a brick. It's not going on a belt. It's going in a backpack, and even then you feel it.
Four hundred grams of mostly lithium and aluminum and plastic that you're carrying so your phone can die slower.
And that's the ceiling Daniel's running into. The market tops out at around twenty to thirty thousand milliamp hours for a single consumer unit. You can find bigger ones, but they're the size of a small car battery and nobody's putting that on their body. The physics is simple. More capacity means more cells. More cells mean more weight and more volume. Lithium ion energy density has improved maybe five percent a year for the last decade. It's not doubling. So the single big unit is a dead end for wearable power.
Which is exactly why Daniel's instinct to distribute the load across six smaller units is not actually crazy. It's the same logic as the carry system itself. Don't put all the weight in one place. Spread it across the pouches, balance the load, and suddenly the biomechanics work.
And it's the same logic as a laptop battery, which is not one giant cell. It's six or eight or twelve smaller cells wired together with a battery management system sitting on top. The individual cells are nothing special. The management system is the whole product.
So the question is whether you can do that at the level of whole power banks instead of individual cells. Take six five thousand milliamp hour units and make them behave like one thirty thousand milliamp hour system. And Daniel's already identified the two hard parts. The cascading charge flow, and the logical controller.
Let me take the naive version first, because it's where everyone starts and it's where everyone fails. You take six power banks and you plug them into each other in a chain. Bank one charges bank two, bank two charges bank three, and so on. The phone plugs into bank six. What happens?
Something drains first.
Something always drains first. Banks don't discharge evenly. They have different internal resistances, different cell ages, different actual capacities even when they're rated the same. The weakest module in the chain hits empty first, and then the whole chain stops delivering usable power, because the phone is only connected to the last bank in the chain and that bank is now dead. You're carrying five banks that still have charge but can't get it to the phone.
So it's not just inefficient. It's actively worse than carrying one big bank.
And the charging side is worse. If you try to charge the whole chain by plugging into bank one, bank one charges bank two, bank two charges bank three. Each hop loses maybe fifteen to twenty percent to conversion losses. By the time you get to bank six, you've lost most of the energy. You're heating up your pouches and accomplishing almost nothing.
The daisy chain is a heat distribution system with a phone charger attached.
That's the naive version. The version Daniel is actually describing, whether he knows it or not, is a parallel architecture with a controller. Each module connects to a common bus. The controller monitors the state of charge of every module individually, and it decides which modules discharge first, which ones charge first, and how to route power around a dead module. That's not a daisy chain. That's a network.
And that requires each module to have its own brain, not just its own battery.
Each module needs a charge controller, a fuel gauge, a communication interface to talk to the central controller, and some kind of bypass switch so that if the module dies or is removed, the rest of the system keeps working. That's the fault tolerance piece. If one module fails, the system degrades gracefully. It doesn't shut down. The phone keeps charging off the remaining five.
Which is the difference between a power bank and a power system. A power bank is a battery with a USB port. A power system is a network of batteries with a coordinator that understands the network.
And the coordinator is the hard part. Not impossible. Just hard. It has to do state of charge equalization, which is a fancy way of saying it keeps all the modules at roughly the same level so no single module gets overworked. It has to handle hot swapping, which means you can pull a dead module out of the pouch and slot a fresh one in without interrupting the output to your phone. It has to manage thermal load, because six lithium cells discharging at once in a belt pouch is a heating problem. And it has to present a single unified interface to the phone, so the phone just sees a big battery and doesn't have to know anything about the network behind it.
So Daniel's slightly crazy idea is actually a distributed energy system in miniature. He's describing a microgrid for his belt.
And here's the part that's going to make you happy. Someone's already built it. In a lab, at least. There's a paper from twenty twenty four, published in MDPI, that demonstrates a working prototype of exactly this. A modular, series connected battery power bank with individual module control, charge equalization, and fault tolerance. Each module has its own controller. The modules communicate with each other. If one module fails, it can be bypassed and the system reconfigures itself to keep delivering power. They demonstrated hot swapping. Pull a module out mid-operation, the output never drops.
So Daniel's idea isn't just feasible. It's been prototyped.
It's been prototyped at the laboratory scale, with the caveats that come with that. The modules in the paper are custom designed. The controller is custom firmware. The whole thing is a research project, not a product. But the architecture is exactly what Daniel described. Individual modules, communication between them, a central controller managing charge and discharge, and fault tolerance as a design requirement rather than an afterthought.
Which raises the obvious question. If the engineering exists, why is the market still dominated by single bricks?
Cost and complexity. A single power bank is a commodity. You can buy the cells, the charge controller chip, the plastic shell, and the assembly for a few dollars. The margins are thin but the volume is enormous. A modular system with per-module intelligence and a central controller is a completely different product. Each module needs a microcontroller, a communication bus, a fuel gauge, a bypass circuit. The controller needs firmware that handles all the edge cases. The connectors need to be robust enough for daily wear. The whole thing costs far more to build than a single brick of equivalent capacity.
And most people don't need thirty thousand milliamp hours on their belt. They need enough to get through a long day, and a twenty dollar brick does that.
The market for Daniel's product is digital nomads, field workers, disaster preparedness people, and the kind of person who thinks about their carry system as an engineering problem. That's a real market, but it's not the mass market. So the big manufacturers don't touch it. And the small players who do touch it end up making compromises.
Let's talk about the compromises, because Daniel asked specifically whether anyone has shipped this, and the answer is sort of, but not really. There are modular power products out there. Nimble has a SharePower system. CTmods makes outdoor power banks. But when you look at what they actually do, they're not distributed arrays with intelligent control. They're either single units with swappable batteries, or they're just multiple independent banks that happen to share a brand.
The swappable battery thing is the key distinction. A product where you can pop out a dead cell and pop in a fresh one is modular in the mechanical sense. But it's not distributed in the electrical sense. The system doesn't treat the modules as a pool of resources. It treats each module as a standalone battery that happens to be plugged in. There's no equalization, no routing, no unified view. It's a battery holster, not a battery network.
That's the gap. The market has modular. The market has large capacity. The market does not have modular large capacity with a brain. The MDPI prototype has the brain. The consumer products have the modularity. Nobody's put them together in a product you can actually buy.
The person who does is going to clean up with a very specific audience. Think about the field technician who's out all day in a vehicle or on a site, no wall outlet for eight hours, running a phone, a tablet, maybe a hotspot. They're currently carrying two or three independent power banks and juggling them. Or the disaster preparedness crowd, who want redundancy not just capacity. If your single big bank dies, you have nothing. If one module in a six module array dies, you still have five.
The redundancy argument is the one that actually sells it for me. Daniel's original framing was about the phone charger being the single point of failure. The solution to a single point of failure is not a bigger single point of failure. It's redundancy distributed across the system.
That's the philosophical payoff he's circling. If the charger stops being the weak link, the personal carry system becomes truly self sufficient. You're not just carrying tools. You're carrying a power grid. Your body isn't just the platform for your gear. It's the infrastructure for your work.
That's the empowering feeling he described. You don't need a place. You need a way to have whatever you need. And if the power is distributed and redundant, you don't need the wall outlet. You've decoupled yourself from the fixed infrastructure.
Which is a very different relationship to the world than the one most people have. Most people are tethered to outlets. They plan their day around charging opportunities. The person with a distributed power system on their belt doesn't think about outlets. They think about their own state of charge, which they can see, and which they can top up module by module.
That's the other thing about the modular approach that beats the single brick. You don't have to charge the whole system at once. You can charge one module while the other five are on your belt. You can leave a module at home charging and swap it in when you get back. The maintenance becomes incremental instead of all or nothing.
Daniel's complaint about having to remember to top up the power bank daily is a real one. A single unit demands a daily ritual. A modular system could be maintained with a rolling schedule. Charge module three today, module four tomorrow. The system never has to be fully down.
Which is how you run a data center, by the way. You don't take the whole rack offline to service one server. You swap the server and the rack keeps running. Daniel has independently reinvented the hot swappable server rack for his belt.
The lab prototype demonstrates that the hot swap is the key feature, not just a nice to have. The ability to pull a module out while the phone is still charging is what makes the system feel like infrastructure instead of a collection of gadgets. It's the difference between a flashlight and a lighting system.
Let me ask the question Daniel would ask. What's actually stopping this from being a product? The engineering exists. The market exists, even if it's niche. What's the blocker?
I think it's the connectors and the packaging. The electronics are solved. The MDPI paper proves that. But a lab prototype uses bench power supplies and custom boards and wires everywhere. A product has to survive being worn on a belt, in the rain, in the heat, getting knocked around. The connectors between modules have to be robust and weather resistant and easy to connect blind, with one hand, while walking. That's a mechanical engineering problem, and it's the kind of problem that kills products in development.
The connector is the product. That's true of every modular system ever shipped. The reason LEGO works is the connector. The reason camera lens mounts work is the connector. The reason most modular phone projects failed is the connector.
USB-C is not the answer. It's a fine connector for a cable, but it's not designed for mechanical coupling between modules. It's not designed to be the structural connection. A modular power belt needs something more like a rail mount, something that provides both electrical contact and physical retention. And that's a custom part, which means custom tooling, which means real money up front.
The blocker is not the battery chemistry or the control software. It's the physical interface between the modules. The thing that has to survive daily wear and tear and still make a reliable electrical connection every single time.
The thermal problem. Six lithium cells discharging at once in a closed pouch is a heating problem. The MDPI prototype probably ran on a bench with airflow. A belt pouch is an insulated environment. You'd need to think about heat dissipation, maybe active cooling, maybe spacing the modules so they don't transfer heat to each other. It's not unsolvable, but it's another reason the product doesn't exist yet.
Daniel's idea is good, the engineering is mostly there, and the market is waiting. It's the classic valley of death between a working prototype and a shippable product. Somebody has to spend the money on the connectors and the packaging and the thermal testing, and nobody's done it yet.
The somebody who does is probably not going to be Anker or Belkin. It's going to be a small company or a crowdfunding campaign or an open source hardware project. The kind of thing that serves the niche first and figures out the mass market later.
Which brings us to the question of whether Daniel should just build it himself. He's an open source developer. He has the skills. The control software is the hard part and that's exactly what he does.
The control software is one hard part. The mechanical engineering is another. But you're right that the software is the piece where a single motivated person can make real progress. The MDPI paper gives you the architecture. The microcontroller ecosystem gives you the parts. The open source community gives you the firmware libraries. It's not a weekend project, but it's not a moonshot either.
Even if the product never ships, the prototype would answer the question Daniel actually asked. Has anyone engineered this? Yes. The paper exists. The architecture is proven. The gap is between the lab bench and the belt pouch, and that gap is bridgeable by someone with the right skills and the right motivation.
I keep thinking about the laptop battery comparison. A laptop battery is a distributed system. Six or eight cells, a management system, thermal protection, fault tolerance. But it's all sealed in one plastic case. The user never interacts with the individual cells. Daniel's idea is to take that architecture and make the modules user accessible. Hot swappable. Individually replaceable. That's the part that's new, and it's the part that makes it a carry system component rather than a sealed brick.
It's the part that makes it fit the philosophy. The carry system is about visibility and control. You can see your pouches, you can reconfigure them, you can swap components. A sealed power bank is a black box. A modular array is a system you can understand and maintain.
Which is the same shift that happened with desktop computers. The sealed appliance versus the open tower. The open tower won with hobbyists because they could see the parts and swap them. The sealed appliance won with everyone else because they didn't want to. The modular power belt is the open tower of portable power.
The market for the open tower was never the mass market, but it was a real market, and it drove innovation that eventually made the sealed appliances better. The same thing could happen here. The hobbyists and the field workers build the modular systems, and the lessons trickle down to the sealed bricks.
Hilbert: I had one of those.
A modular power belt?
Hilbert: A backpack full of batteries. Telecom field work, late eighties. I carried a laptop that weighed as much as a cinder block and a phone that was basically a car battery with a handset bolted on. The laptop took six nickel cadmium cells. The phone took its own brick. I had spares for both, plus a flashlight, plus a pager. The whole thing weighed about thirty pounds and I humped it up tower sites all day.
That's the pre-lithium era. Nickel cadmium cells were heavy and they had memory effect. If you didn't fully discharge them before recharging, they'd lose capacity.
Hilbert: I knew a guy who swore by fully draining his laptop battery every Friday. Took him an hour. He'd sit there running the screen at full brightness waiting for it to die. Then he'd charge it overnight and claim it lasted longer the next week. I never did it. I just carried more batteries.
Which is the distributed approach without the intelligence. You were the controller. You decided which battery to use when.
Hilbert: I got it wrong constantly. I'd grab a battery I thought was charged and it'd be dead because I'd grabbed it the day before and forgotten to put it on the charger. Or I'd have three charged batteries and the laptop would die anyway because the one in it was shot and I didn't know. No fuel gauge, no management, just a bag of cells and a prayer.
That's the exact failure mode the MDPI prototype solves. The controller knows the state of every module. You don't have to remember anything.
Hilbert: I tried to build a daisy chain once. Six double A batteries taped together with wire and a car adapter. I thought I could charge the laptop off it. It got hot and the tape melted and the whole thing fell apart in my bag. Ruined a good shirt.
The duct tape version of the distributed grid.
Hilbert: It didn't work. But I still carry three power banks now. One for the phone, one for the backup phone, one because I don't trust the other two. I've never used the third one. Not once. But I can't leave the house without it.
That's the fear of powerlessness. The battery isn't just a battery. It's a talisman.
Hilbert: It's forty dollars in my pocket that I don't use. But the one time I leave it at home, the phone dies and I'm standing in a parking lot with no map and no way to call anyone. So I carry it. All three of them. Every day.
The single point of failure isn't the charger. It's the fear of the charger failing.
Hilbert: The belt idea would fix that. If one module dies, you've got five more. You don't need the talisman. You need the system. But nobody's selling the system, so I carry three bricks and feel stupid about it.
The market failure in one sentence. The engineering exists, the need exists, and the product doesn't.
Hilbert: Somebody should build it. I'm done with duct tape. But somebody.
There's a version of this where Daniel builds the controller first, as an open source project, and the mechanical stuff comes later. The controller is the part that's actually interesting. The batteries are commodities. The intelligence is the product.
The intelligence is exactly what the MDPI paper demonstrated. Individual module monitoring, state of charge equalization, fault bypass, hot swapping. All of that is firmware. The hardware is just a microcontroller and some power electronics. A capable hobbyist could breadboard a two module version in a weekend and scale from there.
The hard part is not the first prototype. It's the tenth revision, the one that survives being dropped, the one that doesn't overheat in a closed pouch, the one that a non-engineer can use without thinking about it. That's the valley of death.
Hilbert: I'd buy one. If it worked. The real thing.
That's the question to leave on. Will the market ever catch up to the engineering? Or will distributed power stay a niche for hobbyists and researchers while everyone else carries three bricks and a talisman?
The remote work trend isn't slowing down. The digital nomad population keeps growing. The demand for reliable wearable power is only going to increase. Daniel's idea might just be early. The MDPI paper proves the concept. The market gap proves the opportunity. Somebody's going to bridge the valley eventually.
The real takeaway isn't the hardware. It's the mindset. You can carry your entire world on your body if you solve the right problems. Daniel solved the carry problem with pouches and biomechanics. The power problem is next. The solution isn't a bigger brick. It's a smarter network.
Thanks to our producer Hilbert Flumingtop for keeping the show running, even when the batteries are low.
This has been My Weird Prompts, the human AI collaboration podcast.
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