Newbie Learning the Kart Ropes. Lots of Questions...HELP!?

[Functional Artist]

Higher voltage DC components are used in a lot of Solar applications

Hmmm...this one can handle up to 150VDC & 60A (~$20.00) which should be enough for your application
https://www.ebay.com/itm/2729406763...1Fu1TFdXeWFp051s0%3D|ampid:PL_CLK|clp:2047675

or

If you want to "go bigger" this one can handle a bit more amperage 150VDC 80A (~$52.00)
https://www.ebay.com/itm/3345814348...%3D|ampid:PL_CLK|clp:2047675&epid=26030330080

 

[higgypoo]

Higher voltage DC components are used in a lot of Solar applications

Have you seen anyone use this kind before, im guessing they opperate under the same basic rules eh?
Breaker

 

[EpsilonZero]

The voltage rating doesn't need to be your pack voltage if you're not switching it where it is going to be arcing and welding together. I use 48vDC MAX 300A marine switches to isolate and cut my pack into smaller modules for safety and they are handling up to 87.6v with a 700A max controller. Those same "300A" switches can actually handle 900A for 30 seconds, which is overkill for my application. Voltage rated or not, if you're using a precharge resistor, there won't be arcing as long as it has been in the circuit long enough for the voltage to rise (seconds); there will be no difference in potential for an arc to form and your breaker will survive.

 

[higgypoo]

The voltage rating doesn't need to be your pack voltage if you're not switching it where it is going to be arcing and welding together. I use 48vDC MAX 300A marine switches to isolate and cut my pack into smaller modules for safety and they are handling up to 87.6v with a 700A max controller. Those same "300A" switches can actually handle 900A for 30 seconds, which is overkill for my application. Voltage rated or not, if you're using a precharge resistor, there won't be arcing as long as it has been in the circuit long enough for the voltage to rise (seconds); there will be no difference in potential for an arc to form and your breaker will survive.

 

[higgypoo]

Ok, next issue I've run into. Im struggling to find a forward/reverse switch that is rated for a 72v system. Anyone have luck finding something that could fit the bill?

 

[EpsilonZero]

Ok, next issue I've run into. Im struggling to find a forward/reverse switch that is rated for a 72v system. Anyone have luck finding something that could fit the bill?

That probably isn't a pack voltage line. Check and see if it isn't a 12v signal.

 

[higgypoo]

That probably isn't a pack voltage line. Check and see if it isn't a 12v signal.

Good call. I haven't actually plugged the whole system in yet. Need to check voltage on each of these terminations

 

[higgypoo]

@here So, does anyone have a good way of making a decent bushing/hinge for a swing arm? My cart is going to have one and i'm trying to decide the best way to go about it.

 

[Functional Artist]

Ok, next issue I've run into. Im struggling to find a forward/reverse switch that is rated for a 72v system. Anyone have luck finding something that could fit the bill?

Here is an excerpt from my Aerial Atom kart thread
...it has a 60V 2,000 Boma motor/controller combo
https://www.diygokarts.com/community/threads/building-a-go-kart-size-aerial-atom.40167/

"I am gonna use a standard 12VDC 20A automotive type switch to turn the speed controller On/Off
…& a 125VAC 20A On/Off/On switch to toggle from forward to reverse

The ON/Off circuit is "pack voltage" (~60V nominal) actually, it should top out ~ 66.5V fully charged
...but, when I tested, it only carries ~14.5mA

From extensive research, I have come to the conclusion that most any switch that can handle 20A @ 12VDC
...should be able to handle less than .5A (1/2 of an amp) @ 60VDC
* But, this is just my opinion

Even thinkin' it thru, worst case scenario, if the switch fails the SC would just be stuck "powered on"
...or stuck "powered off"
...but, no imminent danger

The SC would still act/operate as normal
...if stuck "off" the system would be off
...if stuck "on" the system would be on
...but, it would not "take off" or be "self powering" or anything
…& the throttle would still operate as normal too

The forward/reverse circuit tested to only ~4.5V
(IMO most any switch should be able to handle 4.5VDC so, I didn't even bother to check the Amp draw)"

It also, has a swingarm rear suspension

 

[higgypoo]

Well, I thoughts id update. Im getting parts together and starting with the chassis. Getting it all laid out. Im no engineer, but I feel like I might have over done the frame. Not sure of the weight yet, but I'd guess it's around 50 lbs. Ill keep posting as I continue.

 

[FlyFrog]

Well, I thoughts id update. Im getting parts together and starting with the chassis. Getting it all laid out. Im no engineer, but I feel like I might have over done the frame. Not sure of the weight yet, but I'd guess it's around 50 lbs. Ill keep posting as I continue.

lookin good, no such thing as overdoing a frame, especially when your putting a large engine on it

 

[madprofessor]

over done the frame

What language is that? My computer can't translate it. Angles, angles, angles, I love them all, can't get enough. All of those angles from the short brace pieces and from the frame itself mean strength through geometry, not through the extra weight of heavy steel. Good job.

 

[Bmr4Karts]

Yeah. I built your exact kart already.

Just do what I did for electronics which you already are. Even your gearing is almost exactly the same, mine was 10/53

I call this kart "Sitting Sideways"

I think you can guess where the name came from. This is a Baja Motorsports Dune 6.5 that bought for $60 without an engine or seat. I swapped the dirt tires to slicks, but I'll be going to sawtooth tires soon due not being able to get up my slick hills. I still have a lot of final touches to do...

www.diygokarts.com

 

[higgypoo]

Some progress on the kart.
- chassis completed
- pedals installed
- axle complete

Running into a few snags here and there.
- how to set the second bead on my rear tires...going to be trying the ratchet strap method. Any other ideas?

- haven't figured out a good way to mount and attach the brake cable to the pedal yet.

Quick wiring and axle test

 

[Functional Artist]

Lookin' good!

Did you notice that the brake caliper, on my Aerial Atom kart, (linked above) is actuated via a cable?
...& that how I did it is mostly described, starting at post #183

* Hey them A-frames kinda look like the ones that I made up for the Electron Crosskart
...have you measured how much "travel" you get? (max down to max up)

 

[redflash]

you really NEED a gas powered motor on that thing ! It needs to make some serious noise and smoke.

Da Redflash

 

[higgypoo]

Lookin' good!

Did you notice that the brake caliper, on my Aerial Atom kart, (linked above) is actuated via a cable?
...& that how I did it is mostly described, starting at post #183

* Hey them A-frames kinda look like the ones that I made up for the Electron Crosskart
...have you measured how much "travel" you get? (max down to max up)

I didn't see that the atom cart had a cable brake. Thanks. Ill go check out that post. Your stuff is always so helpful.
The front struts can move quite a bit with weight on them, but as they stand they'll probably only have about 1-2inches of travel. But if I stand there and jump up and down they can move probably 6 or so.

 

[higgypoo]

you really NEED a gas powered motor on that thing ! It needs to make some serious noise and smoke.

Da Redflash

I'd love to have made a cheaper one with more guts, but our main objective was to stay on the neighbors good sides lol

 

[higgypoo]

Continuing the updates on the kart.
Waiting on a final part for some of the circuitry that I borked. Otherwise, u just need to make a seat and finish the dashboard and she should be ready for her maiden voyage. Fingers crossed the engine can push this thing.
I am struggling to get enough actuation on the brake cable to fully engage the brake calipers. Thought about connecting the linkage higher on the pedal, or maybe removing my pedal stop tab , any ideas? I only get about a 1/2" of movement on the cable and I would like to have at least 3/4"

 

[Functional Artist]

Progress is lookin' good!

A couple of observations, if I may

It looks like the dash may be pretty far away from the driver.

It looks like the caliper could be mounted a little bit closer to the rotor.

The brake "rod" looks like it could be a little bit on the small side (maybe ~1/4"?)
...& it also, looks like that bend (just behind the pedal) may "straighten out" upon hard braking