Brems-Chopper Episode 3: HV and a ski

In the previous episode of Brems-Chopper, it was noted that more volts were needed to continue the experiment.

the volts have happened

Nick holding batteries

I pulled another late one, soldered the third (and final?) 12S4P pack of A123 26650 cells after getting frustrated with my st00pid (not yet working) tab welder.  Solder Just Sticks Better.  Thanks bayleyw for taking this picture of me and the three 40V packs.

batteries more batteries

Now we are in serious DC voltage territory.  I keep it slow and deliberate as best I can, not working on this pack unless there are other more experienced folks around.  Wall voltage giving the potential for “tens of amps” deserves caution and respect.  To balance it out, I bring you the antithesis of “slow and deliberate…”


I bought a 4-pack of unused children's skis at swapfest two years ago for $20 thinking “these will come in handy some day.”  Indeed, they've ended up on a number of silly vehicles including the scooters of Ben and Dane.

Brems-Chopper with front wheel replaced by ski

Welding aluminum is new to me, so the welds are nice and chunky.  Two big things learned:

surface prep is key – everyone hits this one to death because it is rather true.  scuff up everything real well with a brush, and wipe your filler rod clean

preheating is key – cold metal doesn't flow.  Welds went a lot smoother after holding an arc over the region in question for ten or fifteen seconds.  Once the region is preheated, it takes less current to make the puddle appear.  FYI: aluminum has 4-5x the thermal conductivity of steel.

snotty aluminum welding more snotty aluminum welding yet more snotty aluminum welding

Yesterday we were hit with the first snow cover of the year and the time was right for Brems-Mobylen.  Last minute water-protection was added, including a fender and a thick oozing of hot glue around all motor controller holes.

plywood fender hot glue to keep water out of the motor controller batteries mounted to Brems-Chopper

Chibi-Mikuvan and the reincarnation of LOLriokart also took part in the derpy electric vehicle first snowfall ritual.

Front ski's now worn in pretty good.  It could have used a bit more snow between it and the parking lot.