Scooter Battery Replacement

The original Deathscooter battery was kindly made for the Engineering Design Workshop by Shane Colton. Unfortunately, Shane was pressed for time, so he accidentally wired the battery backwards. We discovered this after we connected the motor controller to the battery and the connection exploded. The wires' colors were 'reversed' via heatshrink tubing, and two new deans connectors were soldered to where the old ones used to be. Oh, and the battery didn't have any balance wires either. This battery should not exist. And so in August I built a new battery pack (same specs: A123 8S2P 4400 mAh 26.4V) to replace the old one. On that fine summer day, I did everything except attach the connectors, which is, you know, kind of important.

2.5 months later, I finally got around to finishing the pack. The reason I hadn't done this sooner is that the battery pack that Shane built hadn't exploded yet, and was still performing well despite my extensive usage sometimes requiring multiple ~70% capacity charges per day. The reason I got around to doing it is the darn thing was sitting in N52 almost fully assembled, and I should really be using the pack with balance wires.

Alright here we go. The first step is to put these little tiny connectors on each of the balance leads and put them in a plastic holder so it can be plugged into the charger. A note for anyone trying to build their own pack: do NOT try to strip, solder, or do anything else to two balance leads at the same time. If you try to cut or strip them both at the same time, they will short together on whichever metal cutting tool you have chosen for the task. You and your pack will not be happy. Strip one wire at a time, solder the connecter, crimp, place in the holder. Repeat as necessary, in that order.

Soldered the deans connector onto the main wires. Pack is operational.

- black white brown backwards rainbow +

And we have our fully operational balanced pack!

Looks like we're done for the day. NOPE.

The pack doesn't fit inside the battery bay on the scooter because the wire sticks out the top instead of the side on part of the pack. The segment of wires in front of the conveniently (and accidentally) placed cinnamon toast crunch box needs to be moved from the top to the side.

Carefully slicing open the pack, I am terrified of cutting a wire or worse, shorting two wires with my knife blade. Luckily neither of those things happened.

Black wire was pushed over to the side, and the pack is ready to be sealed up. Wait...where's my duct tape? Crap. Well, floor mate Julia to the rescue... 

Probably the most colorful pack I will ever make.

It fits!

And so Deathscooter was made a bit more colorful. 

Note: I will still not ride this machine until I get a new front wheel, which is in the mail as of tomorrow (hopefully).

Scooter Testing and MORE Brake Repair

Last night from 10-11pm Shane, Charles, Franco, and I did some testing of our scooters in the Albany St. garage. The test consisted of a hill climb from the bottom of the garage to the top level (driving directions: right turn x 20), a distance of about a half mile.

Energy = Power x Time

Deathscooter's results: 11.8 Wh in 78 seconds

11.8 Wh = 544.6W x 78s x 1h/3600s

P=IV

544.6W=26.4V x 20.6A

20.6 Amps average going up the Albany St. garage. Learn something new every day.

"Not enough gang signs."

The Sisters of Anarchy

On to the brake repair portion of the post. Five minutes prior to leaving for the test, I let one of my floor mates who will remain anonymous use my scooter in the hallway. He accidentally made the scooter run itself into a wall which knocked the brakes loose.

"But Adrian, you said the brakes were welded to the front fork!"

"Yeah, J-B Weld."

As a result, the brake calipers now clamped the 'spokes' of the wheel instead of the rim, providing almost no braking at all. On the trip over to MITERS I went full throttle all the way used my shoe to slow down. Good thing I didn't need brakes for the testing.

First attempt: Use picture hanging wire to provide tension to hold the calipers in place.

Looks good, right? No, not right... and not left either.

Now I can't turn.

Attempt 2: Use longer picture hanging wire to provide tension to hold the calipers in place and attach the other end of the wire to something that moves with the wheel.

Several minutes, a screw, and three zip ties later, we have wound the wire around the front of my scooter in such a way that accomplishes our goal. 

Used a screw to tension the wire.

Another discovery during this process: my brake pads are depositing themselves onto the wheel. 

I did reach home safely after this quick fix, but as much as I enjoy the thrill of speculating on whether or not I'll be able to stop the next time I use the brakes, I need to fix this for real. I'm going to try to get access to one of the TIG welders in EMB and mount a steel plate to the front fork, which will hopefully allow for sturdier brake mounting.

Deathscooter Brake Replacement Update

Wow. These bike brakes are five times better than the old brakes ever were. I tested them out on Bay State Rd. before I took to the real streets, and I almost flipped over. Oh well... it was either front brakes or no brakes at all. I now have functional (also very sensitive) brakes that will hopefully last until winter, at which point I will probably have to rethink my transportation modes anyway.

Original post here.

Deathscooter Brake Replacement

Yesterday while riding east down Comm. Ave. I was almost hit by a truck. Twice. The bike lane is never safe. I was wearing a helmet (I think of it as a fashionable plastic hat) which made me feel a little better about the events, but regardless I would have been farther from death if I had full breaking ability, which was currently in short supply. These brakes should have been replaced a few weeks ago, so I can safely say that brake pads have about a month and a half of life on the scooter.

Putting my foot down on the asphalt was more effective than clamping the brakes as hard as I could.

And so I was inspired to travel to a bike shop in kenmore and purchase some $10 bike brake pads. They fit nicely and work very well. I live to ride another day with greater deceleration capabilities.

I'll update on the status of these brakes in a few weeks.