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Trampa DIY build and experience

This summer I decided to jump into esk8ting more regularly and I bought Trampa board, but without any electronic. I wanted to create power parts some self and learn how it is designed.

So before I received the board I started to look what components to use and what I can do on my own. ESCs was the first component I bought at start. At that time I wanted to make something on budget but you know how it ended :smiley: I bought FSESC 4.12 for very good price. As motors I choose Eskating (Maytech) 6374 190kV (Unfortunately I received 140kV version and Eskating stop communication after few emails so I had to do few modifications from an original plan). For battery I wanted LiOn and final solution is 12S6P Samsung Q30. I made the pack someself with welder. It was much more work than I expected and complete time for whole battery pack was around 12 hours of work. It is located on the board that is ideal place for it from my point of view. It is safe, it is easily changeable or extendable and I like the design. Battery pack is twice isolated from vibration. First foam layer is right under pack in the box and another layer is between the box and the board deck. At start I used 3D printed wheel pulleys 77T and metal ones 14T on motors. Motor mounts are completely my work where central parts are 3D printed and sides are milled by CNC from Carbon fiber. between sides are crossbars that are very helpful with keeping right geometry. As remote I used cheap and quite popular GT2B.

After few rides I realize that motors are not what I expected as I mentioned earlier. My top speed was 40kmh that was too slow for me. Also motors going to be very hot in few minutes that I will have to solve before next summer. Because of that I had to modify gearing ratio to 66T on wheel and 20T on motor. I printed the wheel pulley again because of previous good experience and I’m quite satisfied how it behaves. 66T wasn’t available on TG so I designed my own. (You can download here: https://www.thingiverse.com/thing:3911978 ) With this gearing I’m able to ride more than 60kmh that is enough for me at least for now :slight_smile:

For battery my awesome wife created nice textile cover in color of the board.

At that moment I also printed Sparkle case for my transmitter. The size is way better with that.

And now we are in actual state. After gearing modification I lose little bit of acceleration. It is still good but can be better. Before modifications my acceleration from 0 to 40kmh was about 1 second. So now I have 4WD in my mind. I would like to put some smaller motors to front that will fit on the rear side of front axle. I will have to measure it precisely if it is possible.

And at the end I have also one surprising finding regarding to FSESC 4.12. I rode on many places that it cant run 12S or FOC or more than 40A. I broke all this rules. My setup is 12S with FOC and 45A for battery for each ESC (90A booth) and 80A for each motor. Maximum temperature I measured was 35C in the case where I achieved the top Amps values quite often. Only what I follow is rule that say be bellow 60k of ERPM. My motors with 140kv cant achieve it on 12S in any way. With this setup I never had any problem with ESCs.

9 Likes

Never riden a 140KV setup. But 20T motor Pulley sounds big on a EMTB. U got good Tourqe on that board. What are those mounts? 3D printed clamps? iv seen a lot of 3d printed ESC cases.

Maybe u can find some things in this topic

Hi!
Consider to go 8“ instead of changing the gearing so much 66/15 with 8“ on 12s should be a good compromise. If you are a speed freak than probably no, but that gearing should be good with 8“.

In the case or on the pcb? The temp on the pcb is important. I doubt that any 4.12hw can run that cool with this settings. I assume you didn’t ride average 15km/h flat road all the time.

Before you go 4wd, please spend some time over here

Your battery pack doesn’t look very safe to be honest. There quite some points I would suggest to redo and I haven’t seen the full pack yet.

4 Likes

You could even go 66/16. I top out around 40mph.

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There is almost no difference if I change the gearing by size of wheels or by pulley’s. I like the smaller form factor of 6.5" wheels.
The temperature was measured by telemetry so it is temperature or the PCB. I driving most of the time on City so I accelerating or breaking almost all the time and average is about 25kmh.
Can you be more particular about the battery? What exactly looks not safe? I will like to hear constructive feedback. I road whole topic about battery welding that you mentioned.

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20T make sense with this low kv motors. It’s almost same like smaller pulley on higher kv motor. I’m using it mainly on flat road and my goal isn’t to riding throw forrest. Mounts are my own design. Yes 3D printed clamp’s.

For ESC I have a plan to create 3D printed case. I will design my own because I want to put there also receiver and meter pro inside with some holders for antennas.

There is no fishpaper between the p groups and your welds look strange. If you see burn marks on the welds it means you weld with too high settings.
Did you check that the nickel strips you used are pure nickel?
The one strip on the positive terminal looks a bit tiny but I don’t know how your final pack looks so it could be ok depending on how you connected the main positive wire.
I as well can’t see the serial connections and the balance wire routing.

There isn’t fishpaper. I used hotglue instead between all the cells that created more than 1mm gap in one paralel cels and more than 2mm gap between series cells. Yes according to weld’s the ones that are one photo aren’t great. I used Z strip nickel for connecting 2 series by one plate for whole pack that was 100% nickel and it looks well. Unfortunately the straight nickel strip wasn’t 100% most probably and second layer don’t look so good. The first layer looks much better. I welded all strips in 2 layers.

Main power cables are soldered in whole length of lasts series so it should be no problem there.

1 Like