(Numbers and some strings were changed but the gist and 604-character length remains.)
The main function of such a long URL is to redirect desktop users to https://order.fart.cum/cz/cs/purchases/4206913372/ to see the tracking info while mobile users get directed to the app store to get an app (or view the link in the app if they have it). These are (probably) Google Firebase links and they’re absolutely terrible. While they make life slightly easier for existing app users (saves one click but only if they go through the email), this implementation makes it way harder for others to reach the content. Either you get the app, log in there and part with fucking 300 MB of storage, or if you have no mainstream App Store, storage or time, you are forced to do a workaround: Desktop Mode (that may or may not work), rewriting the URL (difficult because it’s so long and includes https: several times, may require hex-decoding), or finding a computer. All this just to check one order from a store you’ll forget about next week.
I have demonstrated that instead of just getting sent the desktop-friendly URL (and perhaps seeing a floating “Open in app” button at the destination), most users are put through extra nuisance that took effort to implement. Sure, some customers are frequent enough to use the app while most are happy with a website but once the business invests in the app, they will absolutely make sure everyone is pushed there despite it being less convenient for both parties.
In fact, the detour could be less than double that. The way to get to Kyiv from Czechia is to get on a train to Przemysl, Poland near Ukrainian borders, from where wide-gauge trains to Ukraine are available. From Zlín, a trolleybus or local train will take you 15 km to Otrokovice where direct trains to Przemysl are available. From Kyjov, the easiest way to get to the Przemysl train is 45 minutes on an express to Staré Město u Uherského Hradiště.
You’re confused. W/m means watts per meter, and the “5Ah” is probably actually 5 A, or the current you can push through the strip (limiting the length to below 2 m).
He meant watts per meter, not minute – the strips can be cut and rejoined. As for the 5 Ah, no clue.
The circumference of a monitor is more than 1 m, so a charger of 3 A at least will be necessary for each. This is why I prefer higher-voltage strips where less current is required and higher resistance is tolerable. Anyway, the power is quite high and this could cause overheating problems.
I am assuming the LEDs are white (blue with yellow phosphor), which always have a roughly 3V voltage drop, this is just a physical fact. Some chips like those in LED bulbs have several LEDs in series for a voltage drop of 6/9/12/15/18 V but this is not the case here.
The vast majority of 5V strips have no step-down switching power supply (aka constant current buck converter) to reduce 5 V from the power rails to 3 V, instead just driving the LEDs with a resistor in series – it drops 2 V and if it’s a 100Ω resistor (usually labeled “101”), it lets 20 mA to the LED as per Ohm’s law. In practice, multiple LEDs are often in parallel to one resistor to save cost, in which case the current divides among them.
The strip may be RGB, in which case the LED voltages are 🔴1.8 V 🟢2.4-3.0 V 🔵3 V and pretty much the same applies. There may be an external controller but it usually just uses PWM to pulse the 5V rail of each color rather than adjusting the current. Individually cntrollable LED strips have a chip driving each LED, and there is just one power rail and serial data line between them.
Police once apprehended a man at a train station in Kyjov (Kiyov), Czech Republic. He was reported to be drunk but they only found him terribly confused. Turns out, he was a Ukrainian trying to return to Kyjev (Kyiv) but a cashier in another town misunderstood and showed him the wrong train.
Fire hazard? Not really. The charger will not provide more than 5 V, 3.1 A or whatever its rating is. Even if the strip fails short circuit (unlikely, most LEDs blow open and there is at least a resistor in series anyway), nothing will receive more than 15 W of power. A 1m cable can safely dissipate that.
Worst case scenario, an LED fails short and its series resistor will receive over 6x its intended power (with 5 V across it instead of 2 V, and its current will increase correspondingly). It is soldered on power-dissipating flexible PCB and will probably not blow open. It will get the area somewhat hot and potentially melt the plastic in the back of the monitor while the rest of the strip keeps glowing but more dimly. Hard to tell if it could get over flammable temperatures with moderate heatsinking and only a few watts of power.
To keep safe, I would deliberately add resistance before the LED strip, using something like a 1Ω 5W resistor (or a shitty long cable). That way, the voltage drops significantly in case of a short. Also, the LEDs will run at lower-than-intended current, which prolongs their life and decreases risk of failure.
Edit: Some microwaves have a 0.8Ω 25W resistor as part of inrush, at least in 230V regions. Feel free to use that, it will happily handle a semi-short circuit. Or you know, an automotive fuse.
The safest option is replacing the whole setup with an LED strip that has no resistors (bare LEDs) and a constant current driver.
The strips use 3V white LEDs, power to which is delivered via resistors or linear current regulators. Unless you see any inductors, there is no buck converter from 5 V to 3 V.
Why does this matter? Well, with resistors and linear regulators, 𝐼in (current in) pretty much equals 𝐼out (current out). So the efficiency 𝜂 = 𝑃in / 𝑃out = (𝐼 × 3 V) / (𝐼 × 5 V) = 60 %. Extra cable resistance will reduce the current, brightness and power, but still exactly 40% of power leaving the USB charger will be wasted before it gets to the LEDs.
However, I would advise against multiple, cheap USB connectors in the circuit: when moving the setup, their resistance changes somewhat and you would get blinking. The worst thing that could happen is a switch, such low voltage cannot spark over an oxide layer and eventually even small movement will blink the lights. I would get a good thick USB cable and solder it directly to one of the strips instead of whatever it came with, connecting the other with some thick wires.
So it does not matter, if you want better efficiency, use 12V (75%) or 24V strips (87%), or get just an LED array without resistors that needs a constant current driver (theoretically 100% but CC PSUs are slightly less efficient). Or make a constant current driver by fine-tuning the voltage of a PSU (by adjusting the feedback resistive divider) to 0.5-1 V above the LEDs’ voltage drop, then using an appropriate resistor to limit the current.