Torsk (Backbone Chassis) Kart

[Functional Artist]

Here is a video of progress so far.

Sometimes "moving pictures" tell more of the story

https://www.youtube.com/watch?v=1eY7ctOPQTE

 

[Functional Artist]

We have a place for the motor, the operator & the batteries to sit
...& the axles/wheels & stuff are ready to go on too

So, lets work on the internals, "the guts" the electrical components & wiring

First up, lets design & make a dash board

What do we want on the dash board?

An on/off switch for the speed controller

An amp/volt meter would be "kool" & handy

Since the batteries are right there, maybe include a 40A circuit breaker
(kinda like an "emergency cut-off" & "main cut-off" switch "right there" visible & handy)

& a charge port too
(since its so close to the circuit breaker/batteries)
(& it would be easily visible so the kart could never be driven away with the charger still attached)

 

[Functional Artist]

I started off by laying the (4) components out & arranging them on a piece of cardboard

I like the amp/volt meter on the top & toward the left
…& the on/off switch next to it

I'll put the charge port on the bottom left
…& the circuit breaker next to it

Also, I want to put protective covers (boxes) over the wiring & components
…& with this arrangement the (2) top components will fit inside of (1) box & the (2) bottom components will fit inside the other
(these are the boxes I got for making them "stupid" Batt-Bridges)

Yup, I like it

 

[Functional Artist]

Ok, we have a plan
...so, lets make it happen

What are we gonna make it out of?
...steel? (heavy & difficult to work with)
...aluminum? (lighter, easier to work & would look kool but, I don't have any laying around)
...plastic? (even lighter & easier to work with)

I still have some black plastic, from the back of an old TV, that I've used for several dashes
...but, I came across something else

Check out this "ribbed" plastic that I harvested off of an old Sony TV

It's pretty rigid & has a nice look & finish to it

A table saw easily trims it down into "usable" pieces

I used the cardboard mock up as a template to mark the layout of of the components
...then, drilled some 1/4" holes & used a jig-saw to "connect the dots" & cut out the big holes
…then, lots of "whittling" using the WPI (work piece indicator) method till all of the components fit nicely

 

[gr8hairy1]

Nice! Great idea on using the back of a tv. I think if it had a border it would look amazing. Maybe metal trim or something that matches the kart.

 

[Functional Artist]

Nice! Great idea on using the back of a tv. I think if it had a border it would look amazing. Maybe metal trim or something that matches the kart.

Thanks & kool idea

 

[Functional Artist]

Now, we gotta get 'er wired up

To help with (understanding) how everything needs to be layed-out
...I drew the dash (front & back)

I also drew the "bigger picture" showing the "main" components
…like the dash, batteries, controller, motor etc. & where they are located

Then, I made several copies (of each drawing)
...so, I could draw out & play with different wiring diagram ideas (without having to draw the "main" stuff over & over)

Here are a couple of my "first draft" ideas

 

[Functional Artist]

Ok, so we basically have the dash lay-out established
...& a good idea of the over-all or "big picture" lay-out
(where the motor, operator, batteries & the dash go)

What about the speed controller? (the brain box)

It could "theoretically" be mounted anywhere but, it would be "best" to centrally locate it

Like between the batteries & the motor & also close to the dash & the hand controls

I could easily mount it, on the backbone, next to the motor or on the back of the seat even
...but, then the speed controller & most of the wiring/connections would be right out in the open & exposed

So, in the "true spirit" of a backbone chassis (most everything is protected within) lets see if we can mount it inside of the backbone, right under the seat

Well, we can't have the speed controller just "bouncing" around in there
(we could but, it probably wouldn't be a good idea)
…& it has to be kinda accessible

Maybe a sliding tray, type of a thing?

This way the speed controller could be mounted to something (not just "bouncing" around) & we can probably stick the shunt in there too

 

[Functional Artist]

I like the concept
...but, I'm not liking that lay-out

It doesn't seem like a good use of the space that we have to work with
...or leave much room for the wiring & connections

I also tried or played around with the idea of
...just mounting the speed controller & the shunt on a flat piece of plastic (not much protection)

Nah, that wasn't it either

Then, I came across this, tray-looking thing
(I think it's the cover off of a fuse box from a car)
...the speed controller & the shunt will fit inside
…& the whole unit slides inside the backbone nice-n-snug
...protected/insulated on all sides except the top
...but, the sides of the tray just fit so there can be no, bouncing around

 

[gr8hairy1]

Wow! That's impressive! Looks like it planned to be that way from the beginning.

 

[ezcome-ezgo]

The stop-motion animation is the best

 

[Functional Artist]

I like this concept but, thinkin' it thru
...there are a few things about it that "bother" me

For (1) thing,

There is not much room inside of the tray, for the connections & connector plugs
(a few may fit in there but, not all of them)
...so, most of the (7) connections would be outside of the box (somewhat unprotected)
&
What about keeping the speed controller kool? (their is stuff in there that gets hot)

Usually speed controllers are kooled by air flow (outdoor breeze or by movement of the kart)
...or if mounted in a confined area, they are usually attached to a metal surface, which acts like a heat sink, helping to dissipate the heat

So, to mount a speed controller in/to a plastic tray
...& then to slide that tray inside of a metal box
(doesn't seem like the best idea)


Playing around with different ideas, (thinkin' outside of the box)

I came up with this...

Why not mount the tray to the front of the speed controller?

This way there is plenty of room for all of the connections (& the shunt too) to be kept (protected) inside the tray
…& the speed controller stays out, to help dissipate the heat

 

[Functional Artist]

It would of been kool if I could of used one of those plastic drill bit box/cases
...like the one I used, to put the shunt in, when I made the "data center" for the e-Lemon-aid kart

But, they are too thick, to fit inside of the backbone
…& not much more than the shunt will fit anyways

They still work nice for a shunt box & have many other possible uses (connector/junction box, maybe an enclosed dash box etc.)

Ya, Ya...Yadda, yadda, yadda
...OK, on with the wiring

 

[Functional Artist]

Moving right along

I bent up a small piece of aluminum & attached it to the bottom of the speed controller
(just with a couple of zip ties)
...the additional area should help dissipate any heat that may be produced

Now for the wiring

We'll start with the battery input wires
...Red positive (+) & Black negative (-)

First, I clipped the battery input plug off of the speed controller
…& attached a 3/8" ring terminal to the (black) negative (-) wire
…& then, connected it to the (P-) side of the shunt
...another piece of black 10g. wire connects to (B-) side of the shunt & goes to the battery pack negative (-)

Next, I soldered a piece of 10g. (red) wire to the (red) positive (+) wire
...so I can extend it up to the dash (for connecting to the circuit breaker)

The motor plug (blue & yellow wires) exits the box next to the speed controller (going back toward the motor)
...the only connection outside of the box

 

[Functional Artist]

I gonna try to post the speed controller wiring connections in pairs

First, two was the battery connection (power from the battery pack to speed controller) labeled "Battery"
…& the motor connection (power from the speed controller to the motor) labeled "Motor"

Next, up is the
On/Off connection (hook to a switch to turn the speed controller on or off) labeled "Lock"
...for this connection, I previously removed the plug & added spade connectors to the speed controller
&
The reverse connection (hook to a switch to activate reverse mode) labeled "Reverse"

I used some 22-4 wire (22g.-4 separate wires) to connect these plugs from the speed controller to the dash/steering wheel
...the red & green wires for the on/off switch
…& the black & white wires for the reverse switch

 

[Functional Artist]

The next (2) connections, the throttle & brake lever, are the easiest ones because they already have plug ends that match the plug ends on the speed controller

A Thumb Throttle is a hand control that sends the "how fast I want to go" signal to the speed controller, it's connection has a (3) wire plug labeled "Derailleur"
...on this one you just have to "make sure" that the controller wires "align" with the throttles wires
(red to red (+), black to black (-) & (in this case) green to white (for the signal)
&
The brake lever is a hand control that activates the brakes
...& has a small switch inside that activates the brake light, it's connection has a (2) wire plug labeled "Brake"

On an electric kart, it also sends a signal to the speed controller (that the brakes are being applied & cuts the power going to the motor)

 

[gr8hairy1]

Looks amazing. I imagine just holding the steering wheel makes you want to go fast. Love the design.

 

[Functional Artist]

Looks amazing. I imagine just holding the steering wheel makes you want to go fast. Love the design.

Yup, I agree

She's comin' along nicely

...as far as speed, I "Ball Park" this one at ~20 MPH

Ball Park equation
MS/GR=ASxTC=IM/FT=FMxHR=FHxMM=MPH

Motor (48V 1,000W) 3,000 RPM
Gear ratio (motor 10T/Axle 60T) 6:1
Rear Tires (13x6.50/6) circumference 42"

3,000 RPM (Motor Speed) /6 (Gear Ratio) = 500 RPM (Axle Speed)
500(AS) x 42" (Tire Circumference) = 21,000 (Inches per Minute/Traveled)
21,000 (IM) / 12 (foot) = 1,750 (Feet per Minute/Traveled)
1,750 (FM) x 60 (Hour) = 105,000 (Feet per Hour/Traveled)
105,000 (FH) x .000189 (MPH multiplier) = 19.85 MPH

 

[Functional Artist]

The last (2) plugs, that have connections in the box, are for the signal wires to the shunt & to activate/power the brake light

The shunt is simple but, the brake light circuit is a bit more complicated
...so, I'll do 'em separately

To connect the shunt to the Amp/Volt meter, I used another piece of the 22-4 wire
...the white wire (the closest one to yellow) connects to (P-) (power minus) the side between the shunt & the speed controller/motor
...the black wire connects to (B-) (battery minus) the side between the shunt & the battery pack
...the red & green wires can be used for something else, later (if necessary)

 

[Functional Artist]

A quick recap

The first connections in the speed controller box was for the "biggies", the Battery (power in) & the Motor (power out)
...the next, connection was for the On/Off switch & the reverse switch
...then, we connected the Throttle & the Brake Lever
…& finally we connected the signal wires going to the Shunt

Now, before we get to the Brake light circuit, lets discuss "fuses"

* All "load bearing" circuits should have a fuse
(anything that "draws power" like a motor, meters, lights)
...& also, anything that "conveys power" like the charge port
...for signal circuits, it's not quite as important

On the kart, the entire electrical system will be protected by the 50A Circuit Breaker (resettable fuse)
...which covers the "high draw" power stuff fine
...but, what about the "small power" stuff like the meter, charge port &/or lights?

The Amp/Volt meter only draws ~50mA
...the charger for this size battery pack (48V 12AH) is only rated at 3A
…& an LED brake light should also draw less than 1A

IMO
...there would have to be a heck of a short, in either one of those "small circuits", to "flip" a 50A breaker

So, "to be safe" it would be a good idea, to add a small (5A) fuse to each of these "load bearing" circuits

So, to connect the brake light
...we need to add a 5A fuse (inside of the box)
...but, we also need to lower the voltage, from 48V down to 12V
(unless we want to use (4) 12V lights, wired in series)
(which would be kool except, that would also quadruple the power draw, just for a "simple" brake light)
...also, to help keep the brake light power draw lower, it's best to use an LED light as opposed to an "old style" incandescent light

An LED brake light probably has a "higher amp draw" than the Amp/Volt meter
...but, since the brake light is only used "intermittently", I think a simple Voltage Divider (like I tested to power the meter) should work
(I'ma gonna giv'er a try, anyways)


So, to hook-up the brake light, I first needed to connect "extension wires" that will reach from the plug on the speed controller marked "stop light", back to where the brake light goes

I used a piece of red ~16g. wire to connect to the SC the red wire (48V+) via a voltage divider (now 12V+) to the brake light
...& a piece of black ~16g. wire to connect to the SC green wire (-) straight to the brake light negative

For the 48V to 12V voltage divider...

I soldered a 3Kohm resistor to the red wire (48V+) coming from the SC wire
...& then, soldered both a 1Kohm resistor & a piece of ~16g, black wire to the other end of the 3Kohm resistor

The other end of the 1Kohm resistor connects to the 5A fuse holder & then to the red "extension wire" going to the brake light
…& the black wire (from the voltage divider) goes to the battery pack negative (-)

Whew ...did you get all that?

Hopefully the pics help