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Thread: Build Diary - Plastic Fantastic - FW

  1. #21
    Al_'s Avatar
    Roboteer

    Quote Originally Posted by Maxamuslead View Post
    but didnt Pressure Points battery work fine in The feather fun time match ? ( has anyone got a video as that was really fun)
    It did but the bot didn't run for very long before I stopped due to the wheel problem and also the current draw in Pressure Point is generally lower then on Plastic. Therefore if it was going to do the same thing it didn't really get the chance. I'll be looking to test this battery too if putting the new one in Plastic fixes the problem.

  2. #22
    mrsam's Avatar
    Roboteer

    Tough little robot you’ve got there, did the most amount of damage to Shrekt it’s taken so far. After watching the first fight back it seems that the slice in your lid wasn’t caused by Shrekt bouncing off the wall, it hit another robot and managed to backflip several times, over the top of PF.
    C507DC74-A8C9-4376-B179-5B7B2075365D.jpg
    Team Riptide

    We do Teamwork we think!?

  3. #23
    Al_'s Avatar
    Roboteer

    Quote Originally Posted by mrsam View Post
    Tough little robot you’ve got there, did the most amount of damage to Shrekt it’s taken so far. After watching the first fight back it seems that the slice in your lid wasn’t caused by Shrekt bouncing off the wall, it hit another robot and managed to backflip several times, over the top of PF.
    Oh yeah, nice catch. I haven't had chance to watch the vids yet that have been posted, going to view them this evening. 10/10 on style from the judges for the backflip!

  4. #24
    Al_'s Avatar
    Roboteer

    Update time following a weekend of rumbles at Portsmouth and my attempt to fix the ongoing issues I was suffering at Manchester.

    As detailed earlier in the thread, I was having problems with the robot stopping after about 2 minutes of battle. Power was still on to the robot and worked fine once it was back on the bench. I had already done a few things to try fixing it at Manchester including swapping batteries and Rx. I still felt the batteries were probably the culprit as they had been left in a cold, outside shed over the winter in a full state of charge. Maybe this had hurt them somehow?

    I went into the first fight with the new Rx, a brand new battery from Overlander and a new main wiring loom. I checked the loom over between events and while there were no issues, the main feed from the battery to the link to the ESC's was clearly getting warmer than I would like, so this was increased to 10AWG size cable fromt 12 AWG. The robot performed fine at the start and then after about 2 minutes, the same problem occurred again, very frustrating.

    Back in the pits there was only one thing left to try and that was to swap the ESCs. I removed the TZ85s and swapped them for a pair of single channel feather 2s. The wiring was a bit of a bodge as I only had the few bits I had with me but it was enough to get them in and working.

    IMG_20180519_160738647.jpg

    Into rumble 2 and it was apparent that these ESCs were driving the motors harder than the TZ85a's. Maybe its better components or different programming but there was a noticeable difference. However them main thing was the the robot finally did the whole 3 minutes flawlessly! Zipping round the arena, slamming into things and shoving the other bots into the walls and what not. I can only assume that I was pushing the TZ85a's too hard and that they were getting too hot and shutting themselves down even though they were cool when I got back to the pits.

    Speaking of the pits, after doing the full fight I was able to check things over and I found a couple of things out:

    1. A charge of the batteries shows I took a shade under 3Ah out of them. That means over 3 minutes my average current draw was about 58A. Certainly higher than I was expecting and that explains point 2.
    2. The robot gets hot. Really hot. Like starting to melt itself hot. The areas around the motors showed that tell tale sign of the dull, rough, cloudy texture of HDPE where it has been melty. A couple of bits were still clear and the HDPE soft.


    In hindsight its probably a combination of a couple of things. The first been that running the Argos drill motors on 5s is really pushing them. 4s is fine and if such a thing as 4.5s existed it would probably be a better limit. Also with the robot being made from plastic and the motor enclosures sealed in, there is no where for either the heat to vent away to or sink in to. In isolation I would probably get away with these but together its probably a bit much. I could help things by making some vent holes in the base and lid but I'm still on the fence about if I actually want to.

    Anyway, this wasn't effecting the performance of the robot to any significant degree so I left as it and ran it for the rest of the weekend. For rumbles 3 and 4 I wasn't driving so I can't say much about those. The only issue happened in Rumble 4 where the driver felt like one side of the drive wasn't right, so stopped as a precaution. Having stripped it down today I found one of the motors was a bit off. Unfortunately I damaged the motor when removing it so I can't be sure what exactly was wrong. I have put a spare motor in, then I have the wiring to the ESCs to neaten up and it will be off to the next event.

  5. #25
    good to see that you fixed that issue, although i want a pushing match now 2 775 at 6s vs 4 550 at 4/5s. XD

  6. #26
    Al_'s Avatar
    Roboteer

    I think you would win that fairly easily as it seems I have spent most of the fights so far turning my tires into bits of rubber left all over the arena. Only 8 fights the bike tires are almost worn smooth. Got some fresh ones to put on for the next event.

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