Electric Longboard Questions

[Montiey]

I've ordered some batteries for my new project.. Still deciding on a motor, but here is something that I can't figure out.
I need my electric skateboard to have braking. So, the ESC I use needs to support active braking (NOT drag braking, unless this would be enough to stop a person moving at 15+mph). I pretty much found that the only ESCs that would have this are car ESCs. I was a bit right, but the ones that have braking also have reverse. This is not good. I only want forward and "slow down to stop" type braking.
What would happen if the ESC tried reverse mode while moving forward?
Can I disable reverse mode and leave braking on?
And finally..
Someone find one! I don't know what to search for, so I only get ESCs with the wrong specs or only some of the right specs.

I'm going to run a 6 cell setup with a motor that (on 8 cells) draws 90A, so 100 A should be fine for whatever 6s draws. The motor will be geared down via belt, for anyone wondering. I want to point to this article: http://www.instructables.com/id/Electric-Longboard/ which says that his setup has regenerative braking (charges battery a little while braking, this isn't a deal breaker for me if unavailable, but would be sweet).

Thanks!

 

[paulshort]

Im not completely sure but wouldnt the motor draw more amps running on 6s then on 8s? It would be cool to use regenerative braking possibly with super-capacitors?

 

[Montiey]

amperage = voltage * resistance, so no. The motor, having a constant resistance, changing the voltage would mean that the amperage would follow directly, and positively. (note that a high resistance is a low "ohm count"; this had me confused.)
I don't know how the regenerative braking works entirely. It may be some cool property of the ESC architecture where it also functions as an alternator, but i'm not sure if all ESCs do this or if you need a special one. (maybe ESCs that have active braking can also do regenerative braking?)

 

[Montiey]

Alrighty..
This ESC is one that I would be okay buying if its usable:
http://www.hobbyking.com/hobbyking/store/__65252__Hobbywing_Platinum_100A_V3_Brushless_ESC_w_10A_BEC.html

This is another, for much less:
https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=71555

They both have braking options (visible on their respective programming cards) tittled soft, medium, hard, etc. Is this a drag brake? The YEP ESC, unlike the hobbywing one has an F3A brake. For this one, which is the drag brake vs active braking, or both? Or, would both ESCs work to do braking for the longboard?

 

[paulshort]

Yes sorry you are right. We have just set up our house on solar and with solar panels you need a smaller charge controller if you use higher voltage.

or am I wrong again

Paul

 

[ScottyWarpNine]

I don't know how the regenerative braking works entirely. It may be some cool property of the ESC architecture where it also functions as an alternator, but i'm not sure if all ESCs do this or if you need a special one. (maybe ESCs that have active braking can also do regenerative braking?)

That is correct, the ESC would have to support it.

If I'm not mistaken, I think all active braking is, is the ESC's ability to brake. Car ESC's have brakes obviously so they don't really make a big deal out of it by calling it something fancy. Some Heli ESC's have "Active Braking" which just means brakes.

 

[ScottyWarpNine]

Yes sorry you are right. We have just set up our house on solar and with solar panels you need a smaller charge controller if you use higher voltage.

or am I wrong again

Paul

In the case of your solar system, Current or voltage isn't so much important as power. To power a 1000W microwave on 120V would need almost 8.4A (Power=Voltage*Current), while running a similar 1000W microwave on 240V would only require about 4.2A. Both microwave are equally powerful, but one uses less current at a higher voltage.

The reason the high voltage controller is physically smaller is because high current components tend to be larger because they need to dissipate more heat.

 

[Montiey]

That is correct, the ESC would have to support it.

If I'm not mistaken, I think all active braking is, is the ESC's ability to brake. Car ESC's have brakes obviously so they don't really make a big deal out of it by calling it something fancy. Some Heli ESC's have "Active Braking" which just means brakes.

What I meant was proportional reversing and not just a drag brake that turns on when the throttle is lowered. Most ESCs have drag brakes, but I need an (car) ESC that uses part of the throttle range for brakes. This is the receiver I will be using. Its not very typical..
http://austindavid.com/jm3/index.php/hardware/3-wiiceiver
How do car brakes work then? (also the remotes?) Is it 50-50 brakes and throttle where as airplane ESCs are 0-100 throttle only?

 

[Montiey]

I found some good brake-type vocabulary:
http://www.hobbyking.com/hobbyking/store/__8993__HobbyKing_Brushless_Car_ESC_100A_w_Reverse_Upgrade_version_.html
This ESC has both forward, backward, brake, and drag brake. No, it won't work for me since it is limited to 4s, but anyway..
I'm assuming now that an ESC needs to support reverse to support brakes. Other ESCs may only support forward and a drag brake. Thank you all for your help.. I found an ESC that has a confirmed brake function, AND says its tested to work with the wiiceiver.
http://diyelectricskateboard.com/product/single-motor-120a-6s-esc/
For $70 its also a good deal compared to anything on HK.

 

[Montiey]

Crap!
The batteries I ordered are 4s, not 3s. This means that the $70 ESC will not work. I found this one:http://www.hobbyking.com/hobbyking/store/__38782__TURNIGY_K_Force_120A_HV_OPTO_V2_5_12S_Brushless_ESC.html and this one: http://www.hobbyking.com/hobbyking/store/__10944__Turnigy_Super_Brain_100A_Brushless_ESC.html
and they both seem fine, but again I can't for the life of me figure out if either of these have reverse/brake capability. Can I get an RC car geek help me out here?

 

[reburg99]

I don't see any mention of those ESC having any braking for reversing functions. If you want braking you should look at a car/truck ESC. Most car ESC have what's called drag braking, which will apply a pre programmed amount of brake when you let off the throttle. This feature can typically be turned off as well. You can normally program a soft start and the amount of braking applied during braking. Why not just use the ESC the guy used in the indestructible? He has a parts list, seems like you can just use what's already proven to work.

 

[Montiey]

Well, the batteries I found on sale were 4s each, so I need something to support 8s now.
Look at that! Its a rare and illusive good deal!
http://www.hobbyking.com/hobbyking/store/__24754__Turnigy_Trackstar_1_5th_Scale_Sensorless_200amp_8s_Opto_Car_ESC.html

This should be nice. The only thing i'm worried about is being able do solder those huge wires..

 

[reburg99]

Good golly that thing is massive.... I could run my Mazda off that.... That's a great price

 

[CarolineTyler]

I've ordered some batteries for my new project.. Still deciding on a motor, but here is something that I can't figure out.
I need my electric skateboard to have braking. So, the ESC I use needs to support active braking (NOT drag braking, unless this would be enough to stop a person moving at 15+mph). I pretty much found that the only ESCs that would have this are car ESCs. I was a bit right, but the ones that have braking also have reverse. This is not good. I only want forward and "slow down to stop" type braking.
What would happen if the ESC tried reverse mode while moving forward?
Can I disable reverse mode and leave braking on?
And finally..
Someone find one! I don't know what to search for, so I only get ESCs with the wrong specs or only some of the right specs.

I'm going to run a 6 cell setup with a motor that (on 8 cells) draws 90A, so 100 A should be fine for whatever 6s draws. The motor will be geared down via belt, for anyone wondering. I want to point to this article: http://www.instructables.com/id/Electric-Longboard/ which says that his setup has regenerative braking (charges battery a little while braking, this isn't a deal breaker for me if unavailable, but would be sweet).

Thanks!

Does this help?
https://www.electric-skateboard.builders/t/what-esc-to-use/908