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LongRat

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About LongRat

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    http://www.fulloption.co.uk
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  • Location
    Wotton-under-Edge, UK
  • Interests
    CNC machining, model engineering, scratch builds, model engine building, RC car racing, model flying.

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  1. LiPo cells are completely, hermetically sealed. You cannot affect the chemistry by putting water on them. The only thing that could happen would be water bridging the connections outside the cell, causing a short. But rain water is not a great conductor, so it isn't going to be a high current even if it happened, and because we aren't talking long-term complete submersion this condition will only be transient if it happens at all. So in this case, I don't think there's anything to be concerned about. Certainly if there was, the fast electric boat guys would have to be thinking more carefully than you and I. Don't think that LiPos are zero hazard because this one issue may have been overblown on the internet though. RC cars are a harsh (possibly harshest) environment for LiPos and outside the designed usage window for these cells. While the chemistry may be similar to phone and laptop batteries, the usage conditions are massively more severe. On top of that, there are no internal safety devices in the batteries used in RC, where these are present in every other usage scenario for these cells including phones, laptops, e-mobility etc. Store them in the proper conditions, and be prepared for them to fail even if you never deviate from the accepted use guidelines and 'specs'.
  2. I applaud you for the perseverance in getting to the bottom of this. Whether it is the specs of the old UBEC or (I think more likely) some sort of fault with it, you have solved the issue. Most people would have given up, well done. This is especially good as your electronics are very nice, you don't see a lot of GM V12s now. Hope you have fun with it.
  3. CNC machined alloy version next to the kit part. I have several ready to ship, hit me a PM if you want one.
  4. You need the (-) wire from ESC to RX or the signal will have no ground. However just thinking this through, doing this might create a 'ground loop' between RX, UBEC and ESC. Many external BECs have ferrite rings on them - has yours? This is to suppress voltage spikes caused by rapid changes in current. Here's one of my Turnigy UBEC units with a ferrite ring as supplied.
  5. If your UBEC output voltage is sagging to under 1V under servo load, that is really bad. You tried a different servo? I can't imagine you would need over 5A unless the servo has a fault.
  6. Looks like you have an LRP Indy ESC. They have BEC. The clue here is that the TEU101 did not show the issue, this is because that ESC does NOT have a BEC circuit, it simply passes the main battery voltage straight to the receiver. The problem is being caused by the ESC's internal BEC circuit output voltage dipping when the ESC is under high load, causing a momentary brownout of the receiver and consequent uncontrolled servo behaviour. The solutions available - put a capacitor (like a glitch buster, not sure how big a capacitor you have tried already) in a spare receiver channel across the +/- terminals, use an external BEC unit, or lastly, run the servo straight off the main battery voltage. There were a couple of the older Spektrum receivers that were sensitive to this. I have had the problem before, also lost laps from a transponder that browned out due to losing power caused by the same thing.
  7. It has a lot of mods. My intention with this was to keep it recognisable as a Hotshot, with the original chassis and front monoshock layout. It races pretty well, but ultimately loses to the Cat XLS and other Hotshot-based cars with upgraded chassis and conventional independent suspension, plus I only run brushed motors and 2" wheels as that's what I like. Changes: Front independent torsion bar suspension system plus monoshock. This is not an anti-roll bar despite how it looks New geometry CNC machined suspension arms, carbon fibre levers, Durango shock Custom steering set up using carbon low profile bell cranks Bump-steer elimination blocks outboard CNC hinge pin braces Rear - CNC tower, aluminium tower mounts and Pro-Line Powerstroke shocks There is a thread on it on Tamiyaclub, but most of the pics are dead now.
  8. Before you bin it, I suggest ripping off all the connectors and direct solder the ESC to the motor, with the shortest leads you can get away with. In my experience with many sensorless systems over the years, it makes a massive difference.
  9. I've never masked this stuff onto paint, only ever clean Lexan. So I can't help you there, sorry. I guess you need to do a test on some scrap first.
  10. I use masking liquid on every shell I do. I would never go back to tape, not even for a 2-colour design with a perfectly straight junction between them. Good masking liquid for RC (Fasmask, Bittydesign, Bob Dively) can be brushed on easily, I use 2 heavy coats applied with a 1" wide brush. The edges you get between colours is razor sharp. No tape can match it. For straight lines, just use a ruler and run your knife down it when you cut the mask. As straight as tape, never bleeds, and an even sharper line.
  11. Still loads of 2S2P out there - not always labelled as such though. Hobbyking's Turnigy Nanotech and Ultimate batts for example (although not all of them are). Also, plenty of 1S2P.
  12. Not as worrying as if it had been really difficult. IMO cases should resist heavy external compression and puncture but should rupture easily from internal pressure. To the OP, you may find 4 cells in there depending on the battery you have. There are lots of 2S2P packs out there. Then you'll really wonder what that balance lead is for...
  13. The voltage across a cell and the charge driven into it by the charger are extremely non-linear. This is the reason that so much more charge is contained within the cell for such a small voltage increase. You are on an almost horizontal part of the curve. With regards to storage charge, I hear some sources saying 50% of total charge is ideal, others 50% of total energy stored. Those are quite different, as each mAh of charge at the high end of the pack's voltage is carrying a lot more Joules of energy than each mAh when the pack is almost dead.
  14. I suggest opening it up yourself, usually when they seize solid it is because something magnetic has been sucked in and jammed the armature. If it needs rebuilding and you don't have the gear to do it, check out Igified RC on Facebook. He does a nice job.
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