ned Productions Consulting

Technology musings by Niall Douglas
ned Productions Consulting
(an expert advice and services company based in Ireland)

Sunday 7th February 2016 12.12am

A recent acquisition of mine is this USB MPower Fireworm 56 CREE LED light in warm white colour which is the most powerful USB powered light I could find on eBay at a claimed 10w (which makes sense as a fast USB charger outputs 5v @ 2A). This is my homegrown solution to emergency lighting during power cuts, so the idea is that due to being USB powered, it can plug into laptops, USB power packs, even the 16Ah lithium car jump starter I bought recently which comes with USB ports. It therefore ought to be very versatile, perhaps even covering camping and other such uses, anywhere where you need a good bit of light. As there are zero reviews anywhere on the web for this product, I thought I'd write a few notes about it.

Before mentioning the problems, I should say it does solve better than anything else I've tried the problem of USB powered lighting, and it gives off - just about - enough light to illuminate a small room with pretty good, if rather directional, light dispersal thanks to its long length. It is far, far better than those USB lightbulbs you can get which are only just about suitable for a very small tent. Its cable comes with a three way switch one of whose settings inlines a PWM to dim the light, so you get an off/low/high sequence which could be useful for saving battery life. So in this sense, it solves my problem quite well, though you probably wouldn't be reading for too long underneath it and there an awful glare looking at it as with all SMD LEDs.

However, there are some problems. Firstly despite its box claiming a 3000K colour temperature, it's nowhere near that warm, I would say 4500K much more accurate, so this is not a warm white light as claimed, more natural white which is better than the cool blue usually given out by cheap LEDs, but still not as good as a proper warm light given the low level of illumination. Secondly, there is absolutely no way this is generating much past 300-400 lumen which I can tell by comparing it to my superb 2w 200 lumen LED filament bulb in the hallway upstairs, and the main reason for that is that it is not drawing anything close to the 10w of power it claims on its box!

Hooking it up to a watt meter shows the problem: it won't draw more than 6w (probably 5v @ 1A after AC conversion), or rather, it won't with any of the fast chargers we use in the West which require USB devices to declare themselves as fast charge capable by putting known resistance values across the data lines, so the charger caps the current to 1A for safety. In China they have a different type of fast charger, basically theirs supplies as much amperage as your device will take and it's up to the device to cap its input. Luckily though Megan's phone is made for the Chinese and came with a Chinese type charger, and plugging this light into that charger yields a significantly brighter light drawing about 8.5w which is probably about 6-7w of light, with the remaining power wasted on heating one side of the tube which gets really quite warm due to the 5v power conversion circuitry just next to the micro USB plug.

So not 10w for sure, and I'm not sure I'd like to run it for long at maximum amperage, internally those power chips must be very hot even with the aluminium case to draw off the heat. I'd say 1A is a much better idea, and I left it on with that for an hour and it only became mildly warm.

Therefore all in all I don't think we are there yet with USB powered lighting! This device was not expensive, and it does fulfil what I bought it for, it just falls short on its advertising which is common with Chinese sourced kit which is suspiciously cheap.

Probably next week I shall be taking possession of a much more expensive emergency lighting solution, a LED lantern which cost five times as much as this and which runs off of four big D-size batteries. I expect that will be capable of producing a phenomenal light and will be much closer to its advertised specs given its cost. I am almost certain to write some notes with photos here about it then too!