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Model Forum / Radio Controlled / Land Models / May 2005Electronic or mechanical speed control?
Which is better for off-road backyard bashing with my old Tamiya Blitzer Beetle (27t Corally and 3000 Nimh)): the standard mechanical Tamiya speed control, or a cheap electronic speed control (with reverse)? I know the latter will deliver some longer runtimes, but will it also take some of the speed and thus fun away? if electonic speed controls took speed away then nobody would be racing with them. an esc is by far the best way to go. there are no draw backs to it. novak is a very reliable name brand and would have a "cheap" speed control that suits your needs. just do a little research. but get rid of that old mechanical speed control. Which is better for off-road backyard bashing with my old Tamiya Blitzer Beetle (27t Corally and 3000 Nimh)): the standard mechanical Tamiya speed control, or a cheap electronic speed control (with reverse)? I know the latter will deliver some longer runtimes, but will it also take some of the speed and thus fun away? if electonic speed controls took speed away then nobody would be racing with them. an esc is by far the best way to go. there are no draw backs to it. novak is a very reliable name brand and would have a "cheap" speed control that suits your needs. just do a little research. but get rid of that old mechanical speed control. Does it matter much if it is high frequency or not?? For bashing, just get a cheap reversible. Don't worry about freq, steps, adjustable braking, etc. That stuff is for racing. Another big advantage to the ESC is that when your battery drains the vehicle simply stops, with the manual the servo stops in it's poisiton and the vehicle continues to run until you catch it and unhook the battery, or force the servo to neutral. > if electonic speed controls took speed away then nobody would be racing with > them. an esc is by far the best way to go. there are no draw backs to it. [quoted text clipped - 3 lines] > > Does it matter much if it is high frequency or not?? > Another big advantage to the ESC is that when your battery drains the > vehicle simply stops, with the manual the servo stops in it's poisiton and > the vehicle continues to run until you catch it and unhook the battery, or > force the servo to neutral. This is only a problem with nitro cars - the electric Beetle will slow down and stop as the battery drains. I've also heard the extra run time ESC's deliver is only 10-15% so ideally you'll get an extra minute or two if your normal runtimes are 10 mins. Time tends to fly when bashing so it's hardly noticeable. The biggest advantage I find in ESCs is the more realistic (smooth) acceleration compared to the 3-speed MSCs. > I've also heard the extra run time > ESC's deliver is only 10-15% so ideally you'll get an extra minute or > two if your normal runtimes are 10 mins. Time tends to fly when bashing > so it's hardly noticeable. The biggest advantage I find in ESCs is the > more realistic (smooth) acceleration compared to the 3-speed MSCs. The runtime improvement will be greater if you drive at part-throttle a lot. If you're flat out all the time, there'll be very little difference in that respect. Jonny I have had a Tamiya Striker and Tamiya Blitzer Beetle with manual speedos and both would drive off into the sunset when the battery got to low. I would have to chase the vehicle down and either pull the battery or move the servo to N manually. At a certain voltage the reciever quits working but there is still enough juice to power the motor slowly. The servo stays in the last position it was told to go to (forward usually). While not a high speed chase by any means, if it is far enough away when it happens it is still a pain. I had one hit an object and stop, but voltage kept going to the motor. By the time I got it shut down the motor was cooked. Some do have off switches, but that is only for the reciever. It will not stop juice from going to the motor. "drive off into the sunset" LOL! ha! ha! ha! Now that is funny! When i read that i could definately envision some chump racing after a R/C vehicle! LOL! I have been there with nitro early on.Only to run for a while,then see the crash,dust cloud and then unfortunately the tears.Packing it all up and going home. Then you start the tally,how much was broken and how much is this going to cost. Worst case scenario is when the parts are on backorder or a serious break(chassis bent,motor cracked) :_( (thats a tear) I definately use ' failsafes' ! This definately brought back some sad memories. "drive off into the sunset" LOL! ha! ha! ha! Now that is funny! When i read that i could definately envision some chump racing after a R/C vehicle! LOL! I have been there with nitro early on.Only to run for a while,then see the crash,dust cloud and then unfortunately the tears.Packing it all up and going home. Then you start the tally,how much was broken and how much is this going to cost. Worst case scenario is when the parts are on backorder or a serious break(chassis bent,motor cracked) :_( (thats a tear) I definately use ' failsafes' ! This post has definately brought back some sad memories. > battery or move the servo to N manually. At a certain voltage the > reciever quits working but there is still enough juice to power the > motor slowly. The servo stays in the last position it was told to go > to (forward usually). While not a high speed chase by any means, if it I find this hard to believe - a receiver requires a tiny amount of voltage compared to a motor - it is always the motor that will die first unless you've managed to change the laws of physics. Or you had a separate battery pack running the two items? The symptoms you describe would only happen on a nitro vehicle where the on-board battery pack powering the receiver goes flat while the nitro fuel keeps the engine going. >> battery or move the servo to N manually. At a certain voltage the >> reciever quits working but there is still enough juice to power the [quoted text clipped - 7 lines] > would only happen on a nitro vehicle where the on-board battery pack > powering the receiver goes flat while the nitro fuel keeps the engine going. It *is* possible to get a (low-speed) runaway with an electric vehicle, using a single battery pack. What happens is the servo moves the speed controller to 'forwards', which connects the drive motor to the battery, which causes enough voltage drop in the drive battery that the Rx/servo can no longer return the speedo control to 'off'. You can get similar symptoms with an ESC, but it's generally only a temporary loss of steering - releasing the throttle cuts drive to the motor in all situations I've come across. Jonny > It *is* possible to get a (low-speed) runaway with an electric vehicle, > using a single battery pack. [quoted text clipped - 3 lines] > voltage drop in the drive battery that the Rx/servo can no longer return > the speedo control to 'off'. Hmmm, this sounds like a job for Mythbusters! I think if the battery has insufficient charge to perform that action, how is it possible to turn an electric motor? Motors draw a significant current to spin their armature, I would imagine a lot less than a receiver would need. My old Frog always slowed to a crawl and never experienced this issue. In fact, I think even the steering servos remained functional (if I lifted the vehicle off the ground to remove the burden of weight) for a perod after there was insufficient strength in the battery to propel the vehicle forward any longer. >> What happens is the servo moves the speed controller to 'forwards', >> which connects the drive motor to the battery, which causes enough [quoted text clipped - 5 lines] > electric motor? Motors draw a significant current to spin their armature, > I would imagine a lot less than a receiver would need. What Jonathan describes does happen - I've seen it myself. The RX and servos have a minimum voltage that they require in order to operate. I don't know exactly what this voltage is but I would suspect it would generally be around about 5V. It doesn't matter how much current the battery can supply, if the voltage is below the required minimum, the electronics within the radio gear will simply not operate. In contrast, the motor doesn't have any electronics (that will only operate within certain voltage ranges), it is just a simple electical device. Therefore, it will continue to operate at a lower voltage than the radio gear. It may not go very fast, but it will still spin. Michael |
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