Written/created/scored by me. Created in Blender / composited in AE / music in Logic Pro X. Lovely client to work for, too.
Lots of these Li-Po battery packs on eBay, going for around £12 from various vendors:
Nice hand-sized battery pack, with a coax plug and socket on flying leads, and a handy little power switch and LED. Comes with a somewhat underspecced charger (350mA – so, around 20 hours to charge).
The battery specs seem too good to be true, though. 6800mAh at 12V? Nearly 7Ah at a fraction of the size of an old fashioned gel battery. Hmm.
To test the battery capacity, I hooked it up to a little LCD telly via a Turnigy power analyser.
The TV takes about 0.3A, so it ought to run for about 20 hours. Ha! To start the test, I charged the battery fully with the supplied charger:
12.77V is a little high, but it’s straight off the charger; it’ll relax back to around 12.6V.
About 6 hours later, it was time to switch it off before the battery flattened itself permanently (10.8V is as low as you should go):
So. Not really 6.8Ah at all, more like a third of that. I think I know what they’ve done, though (assuming they aren’t just out and out dishonest): to create a nominally 12 volt battery, they’ve strung 3 cells together in series – but then they’ve mistakenly added the Ah capacities of the cells together. Connect 3 cells in series, you add the voltages, but Ah stays the same as a single cell; connect them in parallel instead, and you add the Ah up but the voltage stay the same as a single cell. They’ve mixed it up.
The headline, therefore: these battery packs only have a third of their marked capacity. Caveat emptor etc.
The upside (!) is that the little charger that comes with it takes half the time to charge it.
UPDATE: A kind commenter, Unferium, notes below that Li-Po cells can be safely discharged to about 3V per cell rather than the 3.6V I used, which does change the results slightly. The voltage drops off very fast from 10.8V down, so you only get an extra 0.25Ah out of the pack. I think the headline stands
Anyway, let’s see what’s inside. Note: Lithium batteries can explode or burst into flames if mishandled, or if they’re faulty. Do not take one apart unless you know what you’re doing, or you’re an idiot. Thankfully, I’m fully qualified in at least one of those categories.
First, off comes the outer blue shrink-wrap:
… revealing a stiff cardboard “case”. It comes apart easily to reveal:
The actual battery of cells is just the silver chunk; the dark strip on the left is just dense packing foam. Shame they couldn’t just make the whole pack a bit smaller instead – I can’t see what benefit that padding does given that it’s only on one side of the cells. Even if something bad happens to the battery and the cells start expanding, they’ll blow up like a pillow, not out sideways. Ho hum.
Let’s pull the cells out:
Yup, three Li-Po cells in series. Thankfully they’ve each got their own protection circuit (which disconnects the cells before they get overcharged, or so discharged they’re unsafe to charge again):
The 3 cells are extremely securely glued together, so don’t try pulling them apart. If the foil envelope around a cell is punctured, they give off a strangely fruity smell and need to be disposed of safely in a neighbour’s bin. (Not the nice neighbours, the ones on the other side)
Despite their misleading label, they’re still useful battery packs, particularly for Arduino / microcontroller use. 2.2Ah at 12V is still plenty of juice for some projects. Here’s a little wireless monitor I rustled up to monitor our solar panels:
It’s just an LCD, an Arduino and an nRF24L01+ radio module, all cable-tied to the battery:
Lasts for a couple of days between charges, and it’s surprisingly robust. Easy to recharge with the charger that came with the battery (albeit a bit slow).
They’re not as good as they say they are, but they’re still handy.
Stranded wires often need to go into screw terminals:
But they’re not very secure connections, and you have to be careful that you don’t get stray strands of wire sticking out.
The answer to this extremely common problem that blights our civilisation?
So the next time you have to stick a stranded wire in a screw terminal:
… slip a ferrule on the end of the wire:
… squish it up with the nearest tool to hand:
Here, I’m using some crimpers, but you can use pliers, teeth, an anvil – whatever’s to hand. Go wild.
Now that’s a nicely terminated wire, if you know what I mean. You can snip the end off the ferrule with snips if it’s too long for your terminal.
Look at that. Isn’t that better? Strain relief, no danger of stray strands of wire causing short circuits that you spend an hour looking for; it looks neater… too many advantages to list.
To sum up: Ferrules. Oh yeah. Available wherever ferrules are sold.
I’m having trouble with our solar set up – lead acid batteries, it turns out, really aren’t ideal for our usage patterns. So I’m buying a big-ass 60Ah lithium battery (LiFeMnPo4 to be precise) from the Czech Republic. Never had such an exciting looking parcel tracker screen before:
The TV has three modes: analogue TV, digital TV, or Aux input – for using it as a monitor for a VCR or camera. I was a bit surprised at the power readings for each mode:
Subtracting the Aux input power from the other readings shows digital telly takes double as much power to decode compared to good ole’ analogue. On this telly, anyway. Those extra gazillion channels don’t come for free apparently…
So. A new Mac Pro is being birthed as we speak.
Got me thinking about the nature of laptop vs desktop computers. My Mac Pro only differs significantly from my laptop in the number of drives it’s got stuffed in it, and the fact that it’s immobile. The new Mac Pro removes one of those distinctions – you’d be connecting drives with thunderbolt – so really it’s a question of: do I need a computer that is specifically immobile?
I think I do.
Right then. The mission: to mount the Hydra’s base station under my desk, which means mounting the EM globe sideways. It’s the bit that generates the magnetic fields that the handsets use to sense where they are, so mounting it sideways will confuse the computer unless I reconfigure the coil connections.
I’d got this far last time:
My first Blender project:
Written and created by Howard Matthews at Push Pictures for Fingo Interactive Ltd.
Created in Blender (blender.org), composited in After Effects
Music by Terry Devine-King / Adam Drake (audionetwork.com)
Dubbed in Logic Pro.
Since 3D Studio Max doesn’t run on Macs and I’m slowly getting rid of all the PCs in the studio (muhahaha), I needed an alternative 3D package. Had a quick look at Maya but thought I’d better give Blender a go – it’s free and open source, which is always appealing, but when I had a go with it a few years back the interface was a bit clunky and the learning curve looked daunting. Lots has happened since then, though; Blender’s really matured into an incredibly capable package.
No better way to learn than to try and produce a project for real – so this is it: my first Blender project. To keep things relatively manageable I stuck with Blender’s internal renderer, doing a separate render of each element using the “Edges” option to get the outlines, then using AE’s Roughen Edges to erode them a bit. Everything was assembled and composited in After Effects, though Blender has an increasingly powerful compositor of its own now – have to try it next time.
My first go at doing character animation, too; Blender’s approach to skeletal animation seems much simpler and more straightforward than Max’s, but the key thing is that there are tons of free tutorial videos available, courtesy of Blender’s growing army of supporters. Groovy.
Just got hold of a Razer Hydra, a 3D motion controller system aimed at gamers. There’s a base station with a glowing green ball on the top that needs to sit directly in front of you, and two handheld controllers with buttons and joysticks on them. They constantly feed back their orientation and position to the computer, so you can wave them in the air or twist and turn them, and objects on the screen follow along. I’m not into them as games controllers (prefer the ole mouse and WASD meself) but with a bit of hacking and help I’m hoping to use them as motion controllers for my graphics work. Record my motions as I manipulate the controller and apply them to, say, a character’s head on screen. Quick and expressive way to animate secondary characters in animations. Nothing new, but this is dirt cheap – £80! – so well worth a punt, and not the end of the world if I can’t get it working.
The base station is way too inconvenient (and has too many wires attached) to be sat there in the middle of your desk all day. That’s precious real estate, and I’ve got a system for my various keyboards where I can slide ‘em in and out under my monitor stand, and that round thing just doesn’t fit.
The base station seems to work just as well upside-down, though, so I’m going to try sticking mine under my desk. (The base station uses a magnetic field to sense where the controllers are, so this trick won’t work with metal desks, and possibly not with very thick wooden ones, but mine seems to work OK. So far.)
Damn thing is too tall, though,10cm-ish, and I’d keep knocking it with my knees. So let’s void its warranty.
Even knocking a few centimetres off would help; I know the coils that let it do its magic are housed in the black ball on the top, and I’m hoping we can get that off and mount it to the side of whatever’s in the bottom section. Slim the whole thing down.
Ahh yes, the old hide-the-screws-under-the-rubber-feet thing.