Turning off electric motors

Hi, I realized this topic may have been posted here before. I wonder
which is best when turning off electric motors whether Li Polies or
NiMh, by switching off the battery or the throttle leads?
I have both versions and had ruined a Li Poly battery by leaving the
switch on the throttle lead. I hope I had made my question clear.
Wan
Reply to
wanjung
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I always put a swicth in the battery lead circuit (positive side) regardless if there is one in the throttle circuit or not. This switch does not have to be rated as high as the maximum current expected because it is not normally switching this current, a switch rated at 3 - 5 amps has worked fine, just as long as you don't switch it when the motor is at full throttle.
Reply to
Red Scholefield
The only time I ever have a battery in an electric model is when I'm flying it. It goes in when I'm ready to fly and comes out when I land.
Good flying, desmobob
Reply to
desmobob
Thanks, mk
It's a lot more convenient to throw a switch after landing than pulling out a plug. But I do pull the battery plug now that I know better.
I believe Red has the right idea about switching off the battery lead.
Wan
Reply to
wanjung
| It's a lot more convenient to throw a switch after landing than pulling | out a plug. But I do pull the battery plug now that I know better.
Yes. The switch that comes with an ESC turns off the BEC power to the RX, so it'll turn off the motor in most cases. It also doesn't switch much current, so it can be a small switch.
Mostly it's just a `safety' thing -- turn it off when your plane lands so the motor doesn't roar to life due to a glitch. But your battery is still being drained slightly by the ESC, so you don't use it to turn off your model for storage or the trip home. | I believe Red has the right idea about switching off the battery lead.
I'm not sure I agree (with putting a switch there.) Sure, it would be convenient, but it also introduces resistance where there was none before, reducing the performance of your plane. And even if you can put a smaller switch than you would normally expect to handle that much current, it's still extra weight.
I think I'll just stick with pulling the battery connector, though that can lead to the connector wearing out, and you could accidently pull some wires loose.
Of course, I do prefer to put a fuse in there, either between the motor and ESC for a brushed motor, or battery and ESC/BEC for a brushless plane. I realize that if the fuse blows in the latter case I lose all control, but if the fuse wasn't there, the ESC would probably burn up and then I'd lose all control anyways. The fuse adds some resistance and weight, but I think it's worth it. But a big switch? I'm not so sure.
Reply to
Doug McLaren
Mostly it's just a `safety' thing -- turn it off when your plane lands so the motor doesn't roar to life due to a glitch. But your battery is still being drained slightly by the ESC, so you don't use it to turn off your model for storage or the trip home.
You're both right. Actually, only one of my electric planes is switched off by the battery leads. I remember it's because I made that plane too tight for a switch to be located where I wanted by the wires from the ESC to the throttle. Yes, it's a "safety thing" as well as convenience. So if I unplugged the battery in any case, it would be the same as if I had a switch to the battery leads?
Wan
Reply to
wanjung
Here is a good one for that purpose. At least they have worked out well for me.
Radio Shack Model: 275-324 Catalog #: 275-324
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Reply to
Bob Cowell
It's something you have to get used to.
DISCONNECT THE PACK IMMEDIATELY YOU LAND.
A switch of sufficient power and low resistance to entirely isolate the battery is simply too expensive and heavy.
NEVE LEAVE THE PACK IN THE MODEL UNLESS FLYING. Its that simple.
Reply to
The Natural Philosopher
Well, it's not quite that simple to just disconnect. I'd have to first remove the battery compartment hatch, unplug the battery, unzip the Velcro, pull the battery out and store the battery in a safe container. Compared to switching off. One step, and it's safe to pick up the plane.
I do agree with you on never leaving the battery in model for storing or transport home. But when on the field expecting to fly 3 - 4 more times, I don't think it necessary to remove the battery.
Wan
Reply to
wanjung
By all means switch of when picking up the plane, but whenever it is back where you park i between flights, pull the sodding battery out.
Its a lot easier than trying to start an MDS anyway.
If you REALLY want to isolate the battery, fit a thwacking great car fuse and a socket inline to the ESC. 50A or so. Or solder a copper busbar across the blades.
Then just pull the blade out. You will lose a bit of power, but hey, if its that imoportant to you.
If your batteries can do three or 4 flights...
Reply to
The Natural Philosopher
Now you are getting silly. How in the world would you fit a "thwacking great car fuse and a socket inline to the ESC. Or solder a copper busbar across the blades"
Fact is I can fly five, 5 minutes flights with the Thunderpower Li Poly fully charged, even though the battery is not of the latest generation. Maybe more times if I am conservative on the throttle.
The original question was how best to turn off an electric motor, but I believe it has been setled.
Wan
Reply to
wanjung

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