FET modded BCG clocked 20.8 Km/h !!!

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    • #10807
      micro_Amps
      Participant
      • Posts: 1290

      I just put one of my FET modded dual cell booster BCGs on the speed checker (dyno) and it has broken the 20 Km/h mark for the first time.
      It screeeeaaams. Its got a 4.0 pushing bit racer gears and really winds up to amazing speeds.
      I need a bigger room.
      Anybody want to lend me a basketball court?
      :DuA

      P.S. the 4.2 motors are on the way

      Edited by – micro_Amps on 02 June 2003 22:12:56

    • #28444
      barto_85
      Participant
      • Posts: 1321

      wow, that is amazing, someone with a video camera please lend him a basketball court. Sounds really good, what does a standard 2.2/2.6 do with standard gearing etc.

      Edited by – barto_85 on 02 June 2003 22:15:21

    • #28445
      micro_Amps
      Participant
      • Posts: 1290

      Barto, I think about 3 or 4 Km/h.

      My target is 30Km/h
      I think is is possible, I still have a few tricks up my sleeve.
      :)uA

    • #28446
      barto_85
      Participant
      • Posts: 1321

      excellent, can’t wait to hear the results.

    • #28447
      micro_Amps
      Participant
      • Posts: 1290

      I think I need a heatsink on the pcb, things are warming up.
      :)uA

    • #28456
      GT-ahh
      Participant
      • Posts: 774

      thats insane…thats faster than a stock miniz isnt it?

    • #28458
      ph2t
      Participant
      • Posts: 2088

      Great work micro. Why would there be such a great difference from 3-4Km/h to 20km/h+ from the different motors?

    • #28466
      micro_Amps
      Participant
      • Posts: 1290

      4 reasons ph2t,
      1. its a dual cell,
      2. its running FETs instead of transistors
      3. the motor is a 4.0,
      4. and it is now powerful enough to push the big gearing that comes from the kit (bit) racers.
      I just realised I didnt have the highest bit racer gears in either. Might save them for the tricell.
      :)uA

    • #28467
      SurfmyStrat
      Participant
      • Posts: 247

      so when your driving this normal, how long does it take to get up to that speed?? Hows the handling?? How long do the batts last??:D

    • #28388
      perriscope
      Participant
      • Posts: 80

      OMG!!!

      can it turn?? or does it just flip?? it must wheel stand like nothin else!!

    • #28366
      Weapon
      Participant
      • Posts: 16

      rofl thats damn fast, i wonder if the pcb would mount if u tri celled that beast :/

    • #28368
      Cranga
      Participant
      • Posts: 180

      Will it ever end!!!!

      WHAt else can be done to these crazy machines!

    • #28369
      leonli17
      Participant
      • Posts: 602

      now, i can’t wait to get the FET mod a TRicell mod done.:)

    • #28373
      micro_Amps
      Participant
      • Posts: 1290

      Ok, here’s some answers to all those questions……
      Surfmystrat
      Q. How long does it take to get up to speed?
      A. It takes a few meters, like I said I need more room now. I am hoping with a few more mods I can improve the acceleration too. Also traction is becoming a problem.
      Q. Hows the handling?
      A. Good with sticky rears and hard fronts. Needs to understeer heaps or it flips. Turns are wide at high speed but can be made tighter by slowing down, same as a booster with a 3.8.
      Q. How long do the batts last?
      A. I’m using 2 x 150mAH cells charged with my custom charger so I havent noticed a huge reduction in run time. Its all a matter of filling the batteries properly before running it. Your runtime is determined more by the amount you charge in these cars
      Perriscope
      Q. Can it turn?, does it flip?, must wheel stand like nothin else?
      A. Parts 1 & 2 answered already. Yes it does wheel stand if you run in reverse then go flat out forward. With the bit racer gears in it, it is really setup for top speed only and this takes its toll on the torque, so no wheelies. If I put the 12:1 ratio gears in it does wheelies from a standing start but of course top speed is not as high.
      Weapon
      Q. Tricell?
      A. A tricell, FET mod booster. Its on the workbench right now …… watch this space.
      Cranga.
      Q. Will it ever end?
      A. I still have a ways to go yet Cranga! Lots of things to try.
      Q. What else can be done to these crazy machines?
      A. Just you wait and see. 30Km/h…hehehe, who knows.
      :)uA

      Edited by – micro_Amps on 03 June 2003 22:04:06

    • #28321
      Impreza
      Participant
      • Posts: 1124

      Good work u. Pls post pics in your members gallery:)

    • #28322
      Efarel
      Participant
      • Posts: 76

      Hi,
      great job !!

      I made this mod some months ago, thanks to the german website bitmod.tk using 3 Bitchar-A as guinea pigs… one of them died during surgery but the other two are still alive and kicking !

      I did 2 versions, full mosfet (both forward and backward) and a simpler mod with mosfets for forward only.
      Both cars seems to have similar forward speed and, of course, the full mosfets has quicker backward speed.
      Both cars are more powerful, they gained slightly top speed but have a lot more torque and acceleration.

      In the “forward only mosfets” car I used 2 mosfet for steering… wow what an improvement !
      The car is now more drivable and a lot more precise; another big improvement is the car’s ability to mantain trajectory and to recover a missed curve !

      Have you similar results ?

      ciao
      Efarel

    • #28290
      ph2t
      Participant
      • Posts: 2088

      Efarel, I was thinking about this steering mod using mosfets as well. I guess now you can put an extra steering spring in to help keep it straight?

    • #28292
      micro_Amps
      Participant
      • Posts: 1290

      Yes thats true Efarel, because the car has more power, it will drift around corners and then recover, rather than just slide out, grip, and flip over. It also depends what tyres you are using.
      I havent put any FETs into the steering circuit yet, but I think I might have to now, it sounds good.
      Impreza. its pretty much a standard looking internal dual cell with the FET mod done. I will try and get a pic on my gallery later his afternoon, showing the setup so far.
      :)uA

    • #28293
      Cranga
      Participant
      • Posts: 180

      What do you think the life of the car would be like?

      Is it reliable?

      If so you should start marketing them!

    • #28300
      micro_Amps
      Participant
      • Posts: 1290

      Cranga, I think this will be as durable as any other dual cell car. All the fets do is increase the power and they are not a moving part so theres no problems there.
      I am already doing fet mods to peoples cars, they send it to me, I mod it then send it back.
      If someone wanted a dual cell fet modded car I would recommend getting a fet mod done first, then sending it to JamieKulhanek for a dual cell mod. He’s the dual cell mod expert on this forum.

      Good idea on the twin steering springs ph2t, I didnt think of that one.

      :)uA

    • #28282
      Efarel
      Participant
      • Posts: 76

      But the forward only 2 mosfets mod has lesser performance than full 4 forward mosfets mod ?
      The 2 mosfets used by backward speed affect overall performance ?
      The full mod is quicker than forward only in your experience ?

      I’m using a single spring but I think a dual spring will be a good idea.
      I’ll try it tonight !:D

      Efarel

    • #28283
      ph2t
      Participant
      • Posts: 2088

      Let us know how you go, thanks Efarel… 😉

    • #28262
      Cranga
      Participant
      • Posts: 180

      MIcro, Check your PM, IM KEEN!!!:D

    • #28271
      micro_Amps
      Participant
      • Posts: 1290

      Cranga, no probs, check your PMs
      :)uA

    • #27910
      oldtamiyaphile
      Participant
      • Posts: 315

      How much current is the new PCB capable of putting out?

      I recently converted a Bit to propo control (it’s now Zip sized) and the PCB is capable of delivering over 2 amps 🙂 (the most a Bit motor can draw is ~350ma) So I for one have no trouble beleiving the 20km/h top speed.:p

    • #27911
      ph2t
      Participant
      • Posts: 2088

      OTP, the current would be limited by the RDS values of the FET’s. On some other boards people have removed R15 & R14 from the BASE of the H-bridge transistors but I don’t think that would really increase performance. R14/R15 only need to limit enough current to fully saturate the transistors in the ciruit. For all those people who don’t know what we are talking about, this is the H-bridge of the RX pcb.
      h_bridge.jpg

      Pretty! :p

    • #27913
      ph2t
      Participant
      • Posts: 2088

      Micro, check you PM’s.:approve:

    • #27914
      micro_Amps
      Participant
      • Posts: 1290

      OTP, the FETs I am using for this mod can handle up to 4 amps but I’m sure the pcb wont carry it.
      I have a tricell booster that is having some troubles with current flow and heat from the FETs. So the next step is to mount the whole H-bridge externally (off the pcb)with thicker wires to increase current carrying capacity and provide extra cooling. I’ll probably remove the windscreen to allow airflow over the FETs to cool them. They might even have to go outside the car.
      :)uA

    • #27933
      GT-ahh
      Participant
      • Posts: 774

      if the fets get hot just stack them in parallel….they wont get hot after that…and its better if the fets are actually soldered to the board because the longer the wire attaching them the more resistance it has..

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