Coolling battery rc car

Discussion in 'Other Toys/Hobbies' started by Reaper, Dec 21, 2010.

  1. Reaper

    Reaper Member

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    Alright, so I have a hbx awd car for the last few years, I finally get around to replacing the standard 1800 nicad with a 4200 nimh and get a "proper" b6ac charger yesterday, today I fired the car up and it's going freaking nuts. Actually does drifts now and donuts and spins and shit, but then it stopped dead in the water. I pick it up and the motor is hotter than usual and the esc is blazing. I let it cool down for a few seconds, it springs to life again, but then it stops again, repeat.

    So what can be done to help keep it cool?

    The motor already has a heatsink, but I suspect it's the esc/reciever. Any suggestions? BTW, this car is supposed to be parts compatible with tamiya tl01.

    It's this here exactly (I got a yellow instead of red shell though):

    http://cgi.ebay.com.au/HBX-1-10-Mit...Radio_Controlled_Vehicles&hash=item27acd09a6f

    In the picture of the electonics, the little silver strips get very hot.
     
  2. Dr1fty

    Dr1fty Member

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    The little silver strip, (Alum fins) that is the heatsink for the speedy. It's getting too hot, plain and simple.

    Mount a fan onto the speedy if possible, As well as the motor... Move the speedy to somewhere else where it can get some airflow.

    Change the gearing in the car so it goes slower. (Less load on the motor/speedy will mean less heat) For drifting, top speed isn't a requirement.

    Other than that, replace the motor/speedy with something decent.

    :)
     
  3. mshagg

    mshagg Politburo

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    Its over geared. Get a smaller pinion for it.

    Either that or the transmission is dragging somewhere. I wouldnt have thought a stocker should be overheating an ESC.
     
  4. OP
    OP
    Reaper

    Reaper Member

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    Yep cool, any suggestions on solutions and how they hook up, eg fans? :)

    I think I should probably replace the bearings too as I think they're plastic ones.

    I like the speed though, so I really don't want to slow it down.


    So a quick search for the pinon gears gives me 20/21t and 18/19t, what one?

    Yea, the parts side is still new ground for me right now. :)
     
    Last edited: Dec 21, 2010
  5. SLATYE

    SLATYE SLATYE, not SLAYTE

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    The new battery is the same voltage as the old one, isn't it?

    If you're not concerned with looks, you could just take the cover off the car to get better airflow.
     
  6. OP
    OP
    Reaper

    Reaper Member

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    Yea, 7.2v 4200mah nimh. Original kit battery was 7.2v 1800mah nicad.

    Mmmm, I could cut out the shell and give it a real front grill and bonnet air intake. :) Maybe even the windows and put in what looks like that side mesh stuff that the real rally cars have.

    I'd like to put a fan in, but I'm not sure if there are kits or how to connect it to the battery without some sort of basic resistor circuit or something, or even use another dedicated battery.

    Also what Mshagg mentioned about the transmission, sometimes it seems to need quite a bit of power to go in reverse or even start to go forward. Had always been that way. So bearings is a start, what else I'm not sure yet.

    But anyway, damn it was fun while it ran today with the extra juicy battery. :)
     
    Last edited: Dec 22, 2010
  7. SLATYE

    SLATYE SLATYE, not SLAYTE

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    Just get a 12V 40mm fan (this should do, and will work well when the heatsink is obstructing the airflow). A 12V fan should run on the 7.2V batteries, although obviously at lower speed than usual.
     
    Last edited: Dec 22, 2010
  8. OP
    OP
    Reaper

    Reaper Member

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    Oh duur, slaps head. Of course "computer" fans should work fine. For some reason I had 5volts for them in my head. Duh. I'm a bit more awake this morning now. :)
     
  9. mshagg

    mshagg Politburo

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    Fans are not an ideal solution IMO. A properly tuned car shouldnt need fans to remain at an operable temp.

    Im guessing they come in packs of two (tamiya pinions yeah?). The 18t pinion will give you the lowest gearing - i.e. best acceleration, lower top speed and least load on motor/ESC.
     
  10. Sammus187

    Sammus187 Member

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    sounds way overgeared. gear it down!!!
     
  11. OP
    OP
    Reaper

    Reaper Member

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    Ok, the manual which contains a parts list and a breakaway assembly guide shows that it should have a 19t pinion in it already.

    And 20 plastic bearings. I think I should get a few new ball bearing ones.

    I gave it a quick short run inside today too as it's wet outside and I'm not running this in the water, the motor only got a little warm, but the esc was freaking blazing. Gotta be something that's causing a big current draw, or the esc, dunno. Any suggestions on a replacement 2 channel am crystal esc?

    Is this a good replacement, the 104bk? http://cgi.ebay.com.au/TAMIYA-ELECT...pt=Radio_Control_Vehicles&hash=item588745838e
     
    Last edited: Dec 22, 2010
  12. mshagg

    mshagg Politburo

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    The tamiya ESC will be fine if you're only going to be running stock silver can motors.

    Although i still dont think you should need a new ESC for stock motor. Check the wiring connections, might be a massive whack of resistence in there somewhere.
     
  13. OP
    OP
    Reaper

    Reaper Member

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    Alright, looking to hop up now.

    For my chassis, etc, I'm looking at the following esc:

    http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=13445

    Should be a straight drop in right?

    I currently have the stock motor, 540, and I have a couple of 540 mabuchi hi perf motors I can use. I am also considering a 550.

    I know I'll need the bullet connectors too, etc.

    Also next Q, what would be a suitable lipo battery to suit the chassis? It needs to fit the oval battery hole. 2s, (I think, 2 cell?) 7.4v, battery required too.

    Also for the extra little non-power cable on these batteries, that's for voltage detection yea? So I'd need one of these too:

    http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=7224

    And that stays in the vehicle?

    I'd like to know more about lipo, there isn't really any info around on the cables, etc. Then again, might be easier to stick with nimh for this car.
     
  14. Loey

    Loey Member

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    your stock motor heat sink is poor. the fins are perpendicular to the air flow when they should be parallel so the air can flow through them. you want something more like this

    also how do you operate the car? are you holding the trigger full throttle constantly and making it do 360's?
     
  15. OP
    OP
    Reaper

    Reaper Member

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    Ah, makes sense on the sink, I'll look for one. :)

    As for operation, I only do that for a short time for a bit of fun, mostly it's bursts/low throttle as I get the car to go around in 8's or ovals, or only full throttle for straights.

    I played with it yesterday in the house because it's too damn wet outside, just on the lowest throttle that gets it moving, I drove it around for a while in and out of table legs, etc, still ended up overheating. Only did a few full throttles for like 1-2 seconds up the hallway as that's all it took to rocket it through. :)
     
  16. thrillhouse

    thrillhouse Member

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    From what I could see the ESC you linked to is a brushless ESC, which means you can only run Brushless motors. As far as I can see you have brushed motors. There are some brushless ESC that can power both brushed and brushless motors, but they are generally more expensive units. A castle creations sidewider ESC comes to mind.

    Sorry I don't have any other recommendations for you.

    The extra plugs that are used on lipo batteries are for balancing. Basically it allows the charger to see the individual voltages of each cell, so that when the battery pack is charged all the cells end up charged evenly.

    A lot of ESCs have their own internal battery voltage detection, with a cut off limit. What happens is when the battery voltage goes below a set limit it cuts all power to the ESC, preventing you from discharging the batteries any further. The item you linked looks like it just makes a noise when the battery is low, so you would have to listen out for it, but you can generally tell when your batteries are getting flat by the speed that it goes.
     
  17. OP
    OP
    Reaper

    Reaper Member

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    Alrighty, after a bit of advice here and just plain lots and lots of just searching and reading, I finally got my head around what I needed to buy. Got the order coming. :)

    But in the meantime, I put a spare 40/60mm (can't remember right at this moment), fan over the speedy. I just directly soldered it up to the battery line on the esc so when the battery is in it's always on. Gave it a blast today, didnt stop at all, a champ the whole way. The motor though got so hot I actually got a burn on my finger.
     
  18. Loey

    Loey Member

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    ive got my fan plugged into the spare slot on the receiver. you could buy a new heatsink with a fan attachment for the motor and that might help
     

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