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Marxpek

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Everything posted by Marxpek

  1. Marxpek
    I own the same soshine LiFePO4, they are great, about 10C, so no worries there. But the crawler tire you want to use will not work, they slip on the rims very easily, they don't fit very well, losing a lot of power with that (i tried them, a rubber band in both sides of the rim helps a bit, but makes the tire unbalanced) The slick motorcycle tires work well, the motorcross tires work, but not that great, they tend to get bigger (by centrifugal forces) under high rpm and are more "bumpy" than the Trac tires, unlike most people think.. , making them unstable. And i live in the city of Zwolle, let me know if you want to drop by, we could race and make a vid!
  2. Marxpek
    Well, good luck with your speed record attempts! be sure to get your steering right, the smallest twitch in steering will make your car u-turn, roll over, flip or crash at these speeds, i broke about half the parts on the car at least once with crashes, so the money drain doesn't end with batteries alone ;D keep me updated with your progress, i'm very interested! be sure to film your attempts, crashes make good video's ;D I was wondering: how are you measuring the speed? About the batteries: Beware, be safe, but be fast! LiFePO4 will bring what you need (what brand did you get and what C-rating do they have?)
  3. Marxpek
    I'm afraid you won't break the record with the 12 volt setup, its more likely you will break/burn your gear, but if you want to risk that over a record, i'd say go ahead, but i would advice you to find another way. Also the current output with that setup will drop to what the NI-MH can deliver, since they are the weakest link here. Driving is not an issue, stalling the motors is and it occasionally happens, i once had a small twig stuck in my gear house for example, blocking both motors. Forget the rechargeable alkalines, they do not have the power output needed and the have a low lifetime (i saw if you drain em they may only last 20 cycles), perhaps they can work in normal batteryboxes, but not for what you want. I understand you invested in the lion batteries, but i think they can still be useful in normal powerfunction batteryboxes, just not the rc unit.. research batteries, test any type available to you, check the differences, get the maximum expiration dates on them (matters alot in some cases) and yes it costed me a a lot of money in batteries to get the record, especially since i tried to use only "fresh" batteries on attempts. good choice, they are powerfull, but be sure you have the correct charger for them, you cannot charge them as lions, you need a charger with a lifepo4 setting.
  4. Marxpek
    Mixing batteries is a bad idea and is never recommended, it will work but, different internal resistances will cause some batteries to heat up more then others, damaging them or making them leak or even worse... Basically: the NI-MH's will not be able to handle the amps the Lion's provide, the setups is always as strong as the weakest link.
  5. Marxpek
    I found another question i think i can answer in you post (some layout would be better). You have problem reversing the motors when using the lions and not when using the alkalines, i think this is whats happening: When you reverse the motors at full speed you are effectively stalling both engines, asking roughly 3200ma (2x stalled buggy motor @1600ma) from the rc unit and thus your batteries. The rc unit can pass through an unlimited amount of current, so much that it can burn itself up, the 2 buggy motors however, are protected by the thermal resistors (when this electrical component passes more than X amount of current, it breaks the circuit and has to cool down to work again, also found in normal battery boxes), this way the rc unit is protected from burning up. Your lion batteries CAN provide the full 3200ma to the rc unit and will trip the thermal resistors in the motors when stalled (reversing motors at speed) and your motors will need a break. Your alkalines CANNOT provide the full 3200ma to the rc unit and thus will never be able to trip the motors thermal resistor, however they are delivering enough for the system to give good results. (stalling motors is never a good idea and should be a rare occasion and with normal driving you should never reach 3200ma so alkalines do fine) More power, more problems, "better" batteries do not always give better results.. Keep in mind that Lego is pretty good at designing things and this was designed for.. standard AA batteries
  6. Marxpek
    @rkkmmah indicates how long they will last, not really important for speed i would say. What is important is the C value (the maximum discharge rate) you want batteries to be able to deliver enough amps to feed the motors. If you have a 1800mah lion with a rating of 1C it can deliver 1800ma of current, if you have a 1800mah battery with a 2C rating it will deliver 3600ma maximum, If you have a 700mah lion @ 1C it's 700ma current max, 700mah @ 2C = 1400ma and so on. id say 3200ma is what we need for the rc unit at its very maximum.. However the Chinese are masters of cheating with all these numbers (c-rating and mah's) and there are a lot of fake/bad batteries on the market especially the cheap ones. good lion batteries are way higher than 1C, i think its closer to 10C, but i have no experience with them so not really sure. So in theory your batteries should be able to deliver enough amps, but if they sold you bad batteries.... And here is a quote from the article you posted: "they have a relatively high internal resistance, making them unsuitable for high discharge current (for example, discharging their full capacity in one hour)." so don't buy those. Here is the solution to the problem: LiFePO4 3,2v-3,6v 3 cells would be 10,8v max, they have high discharge rates (ofc beware of cheap ones) and they are good for the environment :)
  7. Marxpek
    @agrof maybe i read into words too much and but i was not really referring to the spreadsheet, rather to some comments people made about how people are voting... I just saw frustration from people that expected people to vote for different reasons. Perhaps my statement was too hard and yes i am totally new here on the forum so maybe i shouldn't have said that, since i have no reference, but it was a feeling i got while reading posts. But if i offended anyone: that was never my intention. And yes, a treasure chest of creative engineering and 100% fun for sure, but besides MOC-ers i do see competitors as well (in the same people) which is good in my mind, competition drives some people to new heights, i think the entry topic is proof of that!
  8. Marxpek
    True first: hey @rkkm! welcome here and nice to hear my video got you inspired to build something similar, if you need any help with details (doesn't have a alot ;D) i would be glad to help out. You mention 10,4v is no problem with the rc unit, that might be true, i'm not sure actually and i am by no means an electrician or something, But increasing voltage is not the only thing you are doing here, you are also increasing the current and that is a silent killer here, you can hardly measure the current flowing (especially when in use/drving) i don't know at what current the rc unit fries itself, but i do know you can fry a unit by hooking up more that 2 motors, so lets say 3 stalled 1600ma @ 9v motors fries the unit (4800ma which is insane and would probably melt your Lego wire connections), and with some math i think at 10.4v 2 stalled motors are close to 3700mah so the real question is, when does the rc unit burn up... i can't awnser that for (for now) sadly. When you are using the diode-batteries, the current in the rc unit probably will not increase unlike i thought earlier, but you are introducing electrical resistance as well withing the battery setup, dropping the flow of current the batteries can deliver and heating them up, it doesn't feel right to me, but might be worth a try, but i would really keep an eye out, you will have to try to stall both motors (worst case scenario) with batteries the in the rc unit, i would hate to try it myself...
  9. Marxpek
    I don't think this is any use, the battery box will shut down around 800ma while 1 stalled buggy motor will draw 1600 ma roughly, so the batteries inside the the pf battery box will never get the chance to heat up. the RC unit has no curremt limiter, (and 2 motors connected) so there they will heat up a LOT more.
  10. Marxpek
    @rkkmI would not advice to use lithium ion batteries (or combinations of different batteries) in your rc unit, that unit has no internal protection in it like battery boxes do, if you fry it, its dead... battery boxes will reset themselves with the thermal resistor built in, the rc unit just burns up when the current gets too high (when you increase the voltage on the motor the current is increased aswell). The diode solution is one but there is always the risk of melting/burning parts since that is only taking away the voltage from the motors, but the current that the unit has to deliver increases, i wouldn't risk the (15 year old and hard to find) rc unit just to get a bit more power, but that's up to you. The reason the motors stop on reversing the polarity, probably is because of the thermal resistors in the buggy motors kicking in (they do have them built in), and that should be a warning sign to you, if these protectors were not activated you would have fried your rc unit. And a 10 minute run is very long for the rc unit under high current, with the Lego speed records that i did, i always had problems after a few minutes with the RC unit (with high quality AA batteries) when drawing a lot of current, the system heats up fast and has to cool down a few minutes, increasing the power supply won't make this any better, even worse. I'd say, stick to Lego solutions (AA batteries) to make sure you wont burn up your precious old rc gear..
  11. Marxpek
    The voting is somewhat unclear on how it should be done, the discussion topic has some info on it but not a lot, the voting topic itself has no info on how to vote. To me this is all fine, it leaves room for discussion and interpretation but it also gives voters the space to vote for whatever they like best for whatever reason. I never took any weight/size class in consideration, i just imagined all bots being somewhat similar in size in the battle that played in my mind, building bigger is not better in my mind, building compact is. I also judged it as if it was a real LEGO battle bot fight, not as if it was built with metal, i also considered thermal protectors on battery boxes and such, (a spinner with a direct connected buggy motor is easily countered by blocking the spinner and tripping the thermal resistor, only the rechargeable box would prevent this maybe, rendering the spinner useless) to me this was a Lego contest where we had to consider Lego problems like that (also the reason mine wasn't built with buggy motors). Anyway I don't see anything wrong with how people are voting, there are no clear guidelines for it, so everyone should decide themselves what they find important for a Lego battle bot and that is what is happening at the moment. People might not like it and not get the points they expected, but it is all subjective and based on what others like, a true judge-based contest. Maybe it is a better idea for the future to raffle all prizes under the top 10 contestants (or the top half or something), to me it seems some people are trying to (unknowingly maybe) influence voting and i can understand people are excited to be able to win prizes, but greed can bring out the worst in people (not saying i saw people acting bad here, but i do see frustrations and such) In the end this should be a contest for fun, not frustrations, i'm pretty sure i won't stand a chance of winning anything, but that is not what matters to me, what matters to me is sharing a common goal with similar minded people and then compare and share our projects and solutions. And I thank you all for this! Have fun!
  12. Marxpek
    I did 2 Lego rc speed records, with and without steering, i broke so many pieces i stopped counting, even on video.. Without s-brick; steering with the big ir transmitter for control (you really need to reduce power for steering) and a small remote on the same channel (fast full power output) for straight forward, spinning and slamming might work. but the s-brick will be a lot easier, since you cannot time the sequences incorrectly with that.
  13. Marxpek
    Thank you, that is a a big compliment to me! As you already might know my parts are limited as well, but getting others exited with my design despite that; my goal in this contest is met! Since it's a simple design a lot of people will be able to replicate and try their own fights with their bots (however you do need an s-brick to make it controllable, digital file available, but far from perfect, first attempt at LDD, will improve it later) I know the contest says we shouldn't destroy our Lego, but secretly we all want to try our bots!
  14. Marxpek
    @agrof Woah! after that elaborate excel file i come out on top? it is sturdy and fast, but i guess the fun factor you added was the main score for me? ;) Thanks alot! I never expected to get 10 points from anyone since its such a basic design, but i am glad you see beyond this! p.s. all please use agrof's format ;D
  15. Marxpek
    Voting for creativity, functionality of the weapon system, originality and/or likeliness to win a fight: Good job and good luck everyone! 29: 10 22: 6 15: 4 23: 3 20: 2 3: 1
  16. Marxpek
    This thing is insane! With my bot i barely see only one option to attack and that would be to drive on top and start hammering, otherwise... run? spin in circle around you hope you drive in the pit or something? i don't see real options, really well done!
  17. Marxpek
    @PKWBy the looks of it, it would become at least 5 studs wider than it is now, requiring more and longer braces making it weaker. I think that my setup is actually more fitting to the situation, and with the rubber band in the hub you are way more likely to remove the tire off the hub then to remove the wheel off its axle, so i never thought about changing it, its allowed and its working fine. But agreed that without the rubber band, the portal hubs would be very useful to the system. @Aventador2004 I am big fan of Lego Technic for over 25 years now, sadly i sold most stuff from my youth but started to re buy a lot and now have a decent collection again, but not a room full or something... but i never buy parts, only sets, or whatever i can get used for a nice price. Sadly my budget will never allow me to compete with some others who seem to have way more parts to their disposal, but i see this as a challenge, it makes you think out of the box, find new, but also very often old and somewhat lost techniques to the same problem. And that's what i love about Lego Technic, thinking out of the box, finding solutions to problems (that we create ourselves ;D) and improving on that!
  18. Marxpek
    @PKW well yes i started building in normal mode to find out i didn't have all the parts there, the I switched to extended mode and lost all colors somehow (everything was bright red before...). but thanks for the tips ill try em out later! why didn't i use the hubs? i don't have them available, gotta work with what you got..
  19. Marxpek
    try this: go to your youtube video, then hit "share" (under your subscribe button) and try the link there? that works for me if i try to post your video: @teos
  20. Marxpek
    @ agrof Ah yes i'm sorry, i did not see that video yet, thanks for pointing it out! For the workings i just checked the LDD image, more of a visual working guy then reading about it, but never checked that video.. my mistake!
  21. Marxpek
    i was wondering something about your design: can you arm the flipper if the machine is up side down? picture this: you just used the flipper and then you get flipped, can you arm the flipper to upright yourself like in the video or does it have to be armed before you get flipped? the arming system seems gravity based?
  22. Marxpek
    Thanks. Wasn't really for myself. Just to clarify. But that deadline is today? Asap isn't really a clear deadline ?
  23. Marxpek
    @Milan Is there a deadline for editing the entry post?
  24. Marxpek
    This thing made me laugh so hard! Must be the ultimate whack-a-mole machine! Mayhem all over the place, but my guess is: if it does any damage, it will be to itself, putting all that force on a single lift arm. However i very much like your idea and how it functions! good luck in the contest!
  25. Marxpek
    @Aventador2004Where do the rules state there must be a picture of it? i don't think they say anything about a picture, just that it needs to be under the limit. Assuming it is within size, i don't see a problem with proving that afterwards (today), could be disqualified afterwards if needed. But of course it is not up to me, i would just be sad to see someone getting left out on such a technicality after all that effort!
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