Chassis on bike

The chassis is laid on the bike nicely. Certainly not a perfect fit, but will withstand 10 kilos on it with no worries.
Howeva, there's still nothing that prevents it from tilting sideways.

Now there is:

Cushioned up for the batts to truly feel at home.

Programming the controller

The controller's job is to regulate & also monitor (only to a certain degree, though)

My controller of choice is the lyen extreme modder mark II. Along with the controller, I ordered from Lyen a programming cable for it. You can program virtually every aspect of the controller's functionality using the USB-TTL adapter like: max current to be drawn from the battery, max current going to motor, cruise control, speeds, low voltage cut off, and many others.

RC Lipo Charging & Handling

There are numerous guides & tutorials over the web. And now here's mine.


(M) = Mandatory, must. You MUST follow this rule.
(R) = Highly recommended, but not a must.

First & foremost, each RC Lipo "brick" must undergo the following initiation (in order) upon receipt from the seller:

• (M) Verify the pack isn't swollen. If it is, it's done for, give the pack for recycling.
• (M) Plug a celllog-8 or equivalent, and see that all cells are at most (+/-)0.1v around a certain voltage, and that that voltage is between 3.8 and 3.85v.
  Example for a 6S pack: 3.84, 3.84, 3.85, 3.85, 3.84, 3.84.
  If one of the cells is off by just 0.1v, the cell may be salvageable by several cycles of balance charge & discharge.
  Example for a 6S pack: 3.80, 3.81, 3.79, 3.80, 3.81, 3.81.
  If after several cycles the cell still exhibits the same values, the pack's no good, throw the pack for recycling.
• (M) Balance charge the brick to 4.15. The brick is now almost at full capacity within safety limits.
• (M) Discharge the pack until the first cell reaches 3.0v. If the other cells' voltage is >3.5v, that's a bad sign. Perform several cycles of dis/charge, if the behavior remains, that pack's no good for use.
• Perform several cycles of dis/charge. If any of the cells exhibits wonky behavior, that pack is to be put aside.

Charging & caring:

• (M) NEVER EVER have any cell below 3.0v or above 4.2v.
• (M) Never charge unattended.
• (R) Charge at 1C maximum.
• (R) When not in use, keep the battery's balanced voltage @ 3.85v, that's how cells like to be stored and it will lengthen their lives. Charge the cells to 4.2v close to time of use.
• (M) Discharge cells to no less than 3.5v. Discharge to 3.3v only if must, but keep a close eye because that's when some cells plunge to 0, and.. catch fire or explode.

Sources:
RC Lipo series charging tutorial

The battery pack

So I ordered 20 zippy batteries ("bricks"), and plan to hook them up in a 24s5p pattern.
Each battery is 6s (i.e. 6 cells already hooked in series) to begin with, so I'm gonna make a serial connection between groups of 4 batteries, leaving us with 20/4 = 5 higher voltage batteries. Those I'm gonna connect in parallel, leaving us with a high voltage & high capacity battery. 100v 15Ah = 1332Wh to be exact.

Another schematic demonstrating how the pack is actually wired with one big connector for the controller. This is a serial wiring:

And for the charger, which is PowerLab 6 capable of charging up to 6 cells as its name suggest, we'll parallel all 20 zippies:

Now, that's a looooooot of power. That's enough to carry me 53Kph for 1 hour, or 70Kph for a little less than 1/2 hour (that's the plan anyways).
With a charge time of slightly more than 1 hour, we have acquired quite decent mobility.

I chose the Lithium-Polymer chemistry because it explodes and goes out in flames if treated wrong stocks so much power for such a low weight & price. Please read all you can about LiPo before getting into the business.

All 20 zippy's weigh ~9.5Kg.

Charger

I bought the Revolectrix PowerLab 6, highly reputable across the web, considered the rolls royce of chargers no less.

And I found it to be so, in fact. It checks everything so that any mistake on the user's part is simply met with a descriptive error on the screen, and no damage is done. It even recognizes when the power supply (the input) is running out of power (like when using a battery) and draws less and less.

There's only one gotcha - the balance connector they use is JST-PA, a different one than what is the de-facto standard - JST-XH. So poop on them for choosing that road rather than aligning with the crowd.

Anyways, reluctant to wait several weeks for a proper adapter to arrive in the mail, I chose the ghetto way, and soldered a JST-XH plug's wires directly, in FMA-style wiring, where the positive is on one end and the negative(s) on the other.

I proceeded to connect the battery:

Alright!! The charger sees the pack!

And then the new contacts started smoking... :( Indeed that was poor soldering at start.
Luckily, nothing was damaged, not the charger nor the power supply and not the battery or its wires. Only the soldered wires fried and stuck to eachother.

So, with a fresh & proper soldering this time, I started the charge-discharge cycles, talked about in the next post.

To save considerable time, I charged one battery while discharging another by using that as the power source.

Chassis for battery pack

After giving it more consideration it seems like the more preferable solution is to have the entire battery pack at one location, so it is easily detached from the frame for charging.

For that I made a "chassis" where all the bricks are gonna sit snugly next to each other,
and mount the whole thing on the top tube, like a fuel tank with motorcycles.
I bought some flat bars, adjusted their lengths with an angle grinder, and used DevCon S31 2 Ton Epoxy with 2500 psi (advertised, should be enough anyways) to glue the pieces. (Note that one piece hasn't been glued yet).

I then dropped the glued bars to the floor, and snap they go! Everything back to pieces. The 2-ton caved like nothing :( it fell from no higher than 70cm.
I think I did everything right - sand-papered the surface then wiped it with acetone before applying and let it cure for 10 hours. In fact, even several days later I was able to peel the residues off with a player, so it's not that strong after all.
 So me and tony 2-ton will go our separate ways, and I'll bolt the bars like I should have from the start.

Rim, tire, wheel building...

I went with Ilia@EbikesSF's recommendation and ordered Velocity Blunt 35 26" rim with 12ga (2.67mm) spokes (made by Phil Wood) for a Maxxis HookWorm 2.5.

Using this very simple guide I built the wheel to 99% trueness, 'nuff for me at the moment.

1-cross lacing pattern is about as best as you can get with such a wide hub, spokes are stretched enough.

The axle fits in the dropout perfectly without the need to file - one of the benefits of a DH frame.

 

Stuffs!

Lotta stuff started pouring in...

We have:

• Lyen controller, extreme modder Mark II (highly recommended supplier of high quality electronics).
• Grin Tech's Cycle Analyst v3.
• Full throttle.
• Hobbyking LiPo Battery Medic.
• 3-Way speed switch.
• Cruise-control switch.
• 21 Zippy's.