12V 50Ah portable battery bank

batt bank and light bar

Here’s a portable battery bank I put together for camping and power outage use. Rated capacity is 12V 50Ah (via 3 x 12V 12Ah batteries and 2 x 12V 7Ah batteries wired in parallel). These are used freebies which are sitting at between 60 – 90% so capacity will be a bit less than rated, but for the price I can’t complain. Weight is 18kg.

The case is a Supercheap Auto safe case (found here). Cost $35, which I think is an absolute bargain, as these cases are well designed, if sometimes a little iffy on the quality control of assembly. I also bought myself one of the smaller $18 ones, which is also great value.

Batteries are a bit snug, but this also servers to hold them in place well. They are held down using lengths of 25mm nylon webbing. Small slots were cut in the sides of the case to allow the webbing to wrap around fully. Much simpler than affixing internal brackets to hold. Waterproofing is compromised, however I don’t mind this, as I would prefer the case to have some capacity for ventilation in case of hydrogen build up.

Batteries are wired using 6mm and 4mm automotive wire (what I had lying around) and insulated crimp connectors. There’s a mini blade fuse inline with the output, and a 2 pin JST SM 2.5 connector as the main output. This connector isn’t high capacity (3A max), but I will primarily be using this to run LED lighting, charge USB devices and to power ELV devices (eg plugpack replacement).

The light strips I have pictured above are simply a set of these LED light strips screwed to short sections of PVC pipe with hanging loops. Some twin core figure 8 speaker wire is used for power leads. each tube, which consists of six modules, draws around 250mA at 12V.

Another shot of the side, showing the battery straps:


batt bank


Things to improve/add:

  • 4.65mm^2 wiring and higher quality brass female spade connectors for batteries, with PVC covers
  • multiple JST SM 2.5 outputs (collectively fused at 5A) for running ELV devices and also for charging input
  • small solar panel and charge regulator, probably in a separate case
  • main isolator switch
  • terminal block / busbar to neaten up wiring
  • 50Amp anderson plug (fused separately) for heavy loads (eg inverter)
  • power switches on each light module

Once some bits and pieces arrive from ebay for the above improvements I’ll update.



Net gain?

So, today I cut my finger while I was out. No problem, I’m prepared. Whipped out my EDC kit, mopped up the blood with a moist towelette and applied a band-aid. It’s good to be prepared. However, I cut my finger on a folding knife that had come open in my bag. Being one to always be prepared, I of course always have a folding knife with me.

So, in being prepared, I caused myself an injury for which I was prepared for. I guess I haven’t lost anything, oh wait, except some blood…

Medical Care books – first aid with content

After completing a first aid course recently, I was frankly quite disappointed at the almost complete lack of content present. Granted it was only a two day plus one evening introductory course, however the entire course could have basically been done in about ten minutes by repeating this continuously:

  • Check for danger
  • Check for a response
  • Cover your arse by asking for consent
  • Airway/breathing/CPR/stabilise
  • Call for an ambulance
  • Cover your arse by not leaving till help arrives and documenting the patient condition

Sure, these things are important, but hardly worth the sacrificing a weekend and weeknight (thankfully someone else footed the several hundred dollars the course would have cost)

This got me thinking – I remember first aid courses used to actually give you some skills around treating minor ailments, and deciding when to go to a doctor. What I really want is the ability to treat minor illnesses/injuries, and know what is minor and treatable, and really does need further medical care. Like, if I’m out hiking/camping and I’m either too far away from civilization, or simply don’t want to have to go to a doctor if I can treat it myself.

After doing some searching and discussing this with some friends, I came across the following resources which seem to meet my need:

I haven’t studied these in great detail, however they seem to be what I’ve been looking for – basic medical care when there isn’t a doctor around. I’ve made sure I’ve got a copy on my various computers and memory sticks in case I need them.

Golok / Bolo review


After reading about Golok’s on OldJimbo’s page I decided to give one a try. Initially I was going to get one from Valiant, however I found this one on ebay, (from this seller) and ended up getting it for AU$42 delivered, versus AU$85 for the small survival golok.

After doing a bit more research, it seems to me that it is more like a bolo than a golok as was indicated by the seller, due to the tip heavy blade shape compared with a sabre-like shape as seen on Valiant’s goloks. I could be wrong, as I’m certainly not even close to being an expert on blades. In any case, I’m going to refer to it as a bolo.

Construction is very nice, with the blade being around 4mm thick at the spine near the handle. This is thinned off towards the point. The edge has a convex grind. The finish on the blade is quite rough, with a lot of dents (forge marks?) present over the surface, and a raw finish. I cleaned this up a little by running a sharpening stone over the flat, but due to the dents lots of bits were missed.

I’m unsure of the handle construction method, other than it is not a full tang handle, but it is very solid.

Now, in use! This is the result of about 5 hours work (and no, Harry wasn’t particularly helpful)



It is a hibiscus shrub which I’ve been wanting to get rid of for a while. Springy saplings from 1 to 4 cm in diameter. Unsupported and springy, the bolo got through the thinner stuff in a single slice, with thicker bits taking a few chops. When chopping the saplings into shorter sections on a hardwood chopping block, it got through everything in one chop – about as much effort as using a hatchet.

The edge held up very well. While the edge was not great to begin with – inconsistent sharpness, uneven edge, it did not lose any sharpness at all after all that cutting. After testing with a file, it seems that it is differentially tempered, with the edge much harder than the spine.

The one area which did let it down was the handle. The carving near the butt, which is possibly meant to act as a hook for draw cutting, was quite sharp and caused blisters. This might be less of an issue for someone with smaller hands, but it still had hard edges, as the shape had been cut rather than sanded. A quick touch up with a rasp and some sandpaper made a big difference, although now I will need to re-lacquer or oil the handle.

Overall i think a fantastic buy for AU$42, and I will surely get plenty of use out of it.

Survival kit tools on the cheap

So I’ve been putting together survival kits of late, and come across a number of cheap options which I thought I might share. I’ve been thinking that it would be better having 5 slightly lower quality items that I’m not afraid to lose, than 1 fantastic ultra reliable item that will make me cry (or worse, in a survival situation) if i lose or break it.

This sort of survival kit on the cheap is, I must say, all made possible by the wonderous cheap stuff coming out of china. Since most high quality, genuine name brand stuff now also comes out of the same factories in china, the knock-off stuff is now pretty good, if a bit hit and miss sometimes with the quality control. While it may not be as good as the real deal, for the price I think its worth it.

One great example is the pocket knife below – the gerber knock off shown below is less than a tenth of the price of my CRKT M16-13LE. Now, there’s no dispute that the CRKT is a far better knife, but the cheapie is still very solid. Steel is a bit softer, but it still holds an edge decently and is easy to sharpen. The CRKT is my EDC, but the cheapies go into the various kits I have.

Folding knife – Tanto blade, probably 440a or 440c not properly hardened or similar steel – holds an edge fairly well, but is quite easy to sharpen. Quality control is a potential issue – 1 of 3 had a poorly made liner lock which required repair before it locked properly. At around AU$7.50 each delivered (3 to 5, cheaper for higher quantities), i bought a bunch for my various kits.

LED torch (“Flashlight”)
This one runs from AA, AAA and CR123. Runtime on a rechargable CR123 is about 60 minutes. It has a constant current constant voltage regulated driver, as it gives consistant light intensity right up until the battery protection circuit kicks in. With AA and AAAs you get a dimmer light. Different brightness modes would be nice, but the battery flexibility I think is a bigger bonus. At around AU$11 each delivered, one goes in each kit.

Fixed blade survival knife. A number of chinese sellers on ebay sell these for around AU$25. Full tang, very solid construction, nice handle scales. Blade geometry is nice for slicing (eg skinning), and a nice size for survival work – not too large. The only downside is the sheath, which is functional, but not particularly good.

Fire starters
Again, dealextreme to the rescue! They have ferrocium rods ranging from small to large, from AU$2 up to AU$5 each delivered.

Another handy one is a small cylindrical zippo style lighter. This one features a screw on lid with an o-ring, meaning that the zippo fluid (aka coleman fuel, naptha, shellite) doesn’t evaporate like normal zippos.