Welcome back folks,

In this instalment, we are going to look at how to mollycoddle some bits of sheet metal to make a battery box.

Does anyone remember school where you were tasked with sketching out a plan drawing of a shape, then cutting it out, folding it up and making said shape 3D? Well, building this battery box is a little like that, except with more awesome power tools…and more swearing…and probably less accuracy than when I was 6.

To start with, the main reason for building a battery box is due to the fact I have butchered the frame. By shortening the frame, I have removed where the original battery was mounted. Also, this battery was hidden behind some of the bike plastics, which no longer exist. My challenge was to find a place for the battery to go that didn’t ruin the overall look. I also had to consider the CDI unit (which control the ignition) which had to be relocated due to the new fuel tank I had fitted. I had a couple of options:

  • Go without a battery – You can get a battery delete kit (which is like a big capacitor) but I think this may only run on the 12v alternator (mine is 6v) and gives you limited functionality in terms of electrics.
  • Mount it behind my oil tank: this would have worked out nicely, but I would have had to reweld a few mounting points on the frame. Also, I would have been very tight for the Battery & CDI unit.
  • Mount it underneath the seat: This option gives the most flexibility in terms of room. It is quite common in a lot of scrambler type builds to see the battery mounted here.

I decided to go with the under-seat methodology. This meant I had to go battery shopping to find a sealed battery, which would be happy to be mounted on its side. My original battery would leak if turned on its side, and nobody wants hydrochloric acid burns (although it may be used to clean my tank.) I’ll just take a moment here to talk about how much of a MONUMENTAL PAIN IN THE ASS 6V systems are! If I had known I was going to struggle all the way through this build to find sleek indicators, brake lights, switchgear I think I would have upgraded to the 12v system. Even finding a battery that was a sealed unit was a bit of a nightmare…live and learn or something.

So I managed to source a Lucas sealed battery from which actually powers those mobile scooter things…I mean, one of those is technically going a lot faster than my 130kg balance bike right now so I am sure it’s up to the task.

With the battery sourced, I could start looking at the battery box and how it would look. Whilst I had ideas if how it was mounted, I think if I was to do this again, I would definitely firm up this plan before going head first into cutting metal.

I decided where exactly the battery box would go on the frame and cut a sheet of cardboard as a template. I had to be able to mount both the battery box and the CDI (Capacitor Discharge ignition) in this space.

The next stage was to cut up all the various lengths of metal required to build this grown-up jigsaw set.

I think I was a bit like Goldilocks (straberryblondilocks) with the cutting methods. I trialled 3 different cutting methods. Hack saw (too much effort), Dremel (not enough guts) and an angle grinder with cutting disc (just right).

Caution…may contain bad words

The key to getting a straight line is to use a £5,000 sheet metal cutter. If you want passable, take your time, or even use the hack saw to make a channel for your grinder to go through. Mine worked out perfectly fine for the purposes of what I need.

Now the fun piece, assembly! These welders magnets are a lifesaver. They hold everything square, allowing you to mock up and make any fine adjustments. I had to lob 1mm off here or there but it was looking good.

To weld this together, I decided to weld on the outside of the box and grind the welds flush. I cut chamfers into the edges to be welded to allow a wider area for the weld to penetrate (Thanks Glenn).

This process was relatively straight forward and a good chance to tighten up my welding. See below.

I then ground all the wells flush, looks pretty good (but I’m biased):

The next step was to mount to the bike. This caused a bit of head scratching. the mounting I would use to secure my seat were the same ones I wanted to mount the battery box to. In the end, I decided to repurpose (bend the living bejesus) part of the frame that already had captive nuts present. And build another mount for the back mount, which was welded in place.

This part was pretty fiddly to get alignment with the frame, and welding upside down. The box is mounted now and looks decent enough. The next step is to drill a hole in this and mount the under-seat ignition before it gets sent to the powder coaters (and buy an ignition that will work

I have a few lessons learned for next time

  • Maybe buy something thinner than the 3mm thick offcuts of sheet metal I was given to practice on after my welding school. This has ended up quite clunky. It was a breeze to weld because it’s a bit thicker, but it means the finished product is quite heavy.
  • Invest in a bigger refillable welding bottle – Yup MORE GOD DAMN WELDING BOTTLES REQUIRED. There was a lot to be welded together on this
  • FFS remember to cover up EVERYTHING in the garage when grinding welds flat – I have been removing metal filings from every nook and cranny of my garage (and myself) for weeks..or do it outside. Maybe more on that in another post…it had some repurcussions.

That’s it, for now, folks, plenty of stuff progressing in the background getting this build ready for the show in london. I have LOADS of video footage to compile but building a bike is getting in the way…

To be continued,

Struan

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