Radio Controlled Boats For Sale

Low voltage relay switch (trigger under 2.5volts)?

digitalbiju asked:


I am trying to increase the voltage in an RC boat to produce more speed by using a relay to isolate the motor circuit. The voltage that comes from the original circuit is about 2.5 volts. Does a relay exist that can trigger at 2.5 volts or less?
what i’ve actually done is add another circuit into the boat, the weight isn’t too much, and whats happening is i want the 2.5 volt relay so that i can have the switch between the 2 different circuit, because i’m afraid that the receiver for the RC will short out with so much voltage, therefore i’m using the 2.5 from the original to run the RC part, but a relay added in there to switch the circuits and have the 9v battery i have added with the new 9V motors, (there are 2 separate motors for each propellor). The question was just if anyone knew of a 2.5 volts or lesser relay trigger because the lowest one i found was 5V at radio shack, and can’t seem to find any online less than 5Volts…..

Toped Rated RC Boats

3 Responses to “Low voltage relay switch (trigger under 2.5volts)?”

1. cutekittenkyti says:

   April 4, 2010 at 5:33 am

   a relay is not a voltage amplifier
   The most a simple small relay like that can do is open or close a circuit once it detects 2.5 volts. I think you are saying you want more acceleration. As in you want the 2.5 volts to be applied all at once. But if your boat has no set acceleration, just turning it on and hitting the full throttle would do the same thing. The relay will also decrease the efficiency of your boat, and also add weight, thus making it slower.

   If you want to increase the voltage, you would need a transformer. But even though the voltage increases, the current would decrease proportionally. What you want is an increase in power to the motor. But with a transformer the power provided to the motor would be the same, and if the boat is engineered correctly, at levels that are not appropriate for the motor. And again you are adding weight and decreasing efficiency.

   There is no electrical device that can increase power without a link to an outside source of power.

   You could tinker with the battery and the alternator and the motor in order to increase efficiency to make it faster. But again, if the boat is engineered correctly, it should be at optimal efficiency.

   You could add a battery with a higher voltage difference, but again, the motor might not work at highest efficiency and you might even damage the motor.
2. Peter H says:

   April 5, 2010 at 8:21 pm

   The only sensible way to produce more speed is to increase the voltage, i.e use a bigger battery. The only other possibility is to review the motor, which might be running too low a revs/min for a given voltage. Your idea of a relay is a non-starter (it does nothing which the motor controller does not already do). cutekittenkyti’s idea of a transformer is also a non-starter, as transformers only work for AC voltages.
   When you say the original circuit voltage is about 2.5 volts, it sounds as if you are using two rechargeable NiCd or NiMH cells. You will get an immediate benefit from adding a 3rd cell. or, if you are familiar with the handling and potential hazards of Li ion cells, from using a single Li ion cell instead (more expensive). Talk to your dealer.
3. Toney says:

   April 6, 2010 at 7:57 am

   Why not use the 9 V battery to switch a relay.

   OR

   Use a transistor as a switch – using the 2.5V to turn on the transistor to allow the 9 V to go to the 9 V motor.

   OR

   Use a transistor to turn on the relay if you need more than just one connection.