Overvolt drillmotors

[Guest]

I was wondering becaus I am building a 10 bar flipper and the valve that I have works on 24V. Now my drillmotors are 14.4V. So I was wondering if you could overvolt them to 24V. I was also thinking about seting the screw on the electronise speedo down to 75% of the maximum power but I am still not shore If my motors wil burn out. Does anyone have experience with overvotling drillmotors??

Thanks

[ewan]

Overvolt drillmotors

I have done many tests with drill motors (and still have around 10 lying about or burnt out ). If you want to overvolt to 24v, try to restrict the power going into the drill motor via the speed controller if possible, but no matter what you do with current limiting etc, you must use small wheels if you are to go to 24v. Anything over 70-80mm is too much and will strian the motors too much.

I wouldnt advise running on 24v at all infact but you can do some things to reduce the chance that they will blow.
- Make sure all air vents to the motor are open and that air can travel freely around it.
- If possible find a heat-sink from RC cars/planes to fit the motors (there are some sizes that would do)
- Use the correct amount of limiting from the controller.
- Use smaller wheels, around 60-80mm should be reasonable

How much current does the valve take? As you could use a regulator to give the drill motors about 18v, which would be fine for running, and give the valve 24v (only using one 18v battery).

Cheers, Ewan
http://www.micro-maul.co.ukwww.micro-maul.co.uk

[woody]

Overvolt drillmotors

Get a 12volt coil for your valve.

[Guest]

Overvolt drillmotors

Heat-sinks wont be a problem becaus I have four of them laying here. (I have 3 rc-cars)

But the reason I want to overvolt the motors instaid of geting a 12V valve is becaus you will get more power from the drive and you need bigger batterys for the same amount of Amps on 12V then on 24V. (weight)

And the screw on the speedo sets how much Volt gows to the motor om maximum rotation of the joystick.

I was also thingking about a resistor or something like that between the speedo and the motor to lower the voltage.
But I dont know mutch about resistors and stuf so maby someone can help me on this area.
Like how much Ohm the resistor should be if I want half the voltage.

I found a circuit on http://www.circuitsonline.nlwww.circuitsonline.nl that lowers the voltage from everything that has a higher voltage than 12 volt.
But that only works up to 5A and thats to less for a drill motor.

[philip_taylor]

Overvolt drillmotors

Resistors turn electrical energy into heat energy. This would be wastefull and the resistors would quickly fail. Your first idea is a winner. I was also thinking about seting the screw on the electronise speedo down to 75% of the maximum power

I like Woodys solution to your valve coil voltage problem.

[team_ireland]

Overvolt drillmotors

another option is to have a booster to your valve and run 14.4v on your drills.

This system is used by both myself and G3 in there robots.

We have 14.4v for the whole of the robot and then on a seperate feed from the 14.4v battery we have added a 9v PP3 battery in series giving 23.4v which switches the solenoid. Not had any problems so far.

Regards
Ian

[ewan]

Overvolt drillmotors

If it is possible to run off a PP3 battery for a valve, then it should be quite easy to make a regulator to feed the solenoid. All of these do reduce the chance of motors blowing, and will mean you dont habve to go to the hassle of installing cooling or heat sinks.

You may have less power, but the performance of a 14.4v drill on 14.4v isnt too bad, and should be fine for a LP flipper bot.

As Philip said, resistors are designed to turn the enerygy into heat, any resistor able to handle the current a drill motor is likely to draw would be large, and probably affixed to a heat sink, so forget that idea.

If you use 14.4v then you can use two Ni-Mh 7.2v race packs in series, which should give enough power for two drill motors and will be around half the weight of ni-cad packs.

Cheers, Ewan

[team_ireland]

Overvolt drillmotors

Ewan I am really not understanding where you are going. A regulator reduces the voltage. That means given an imput of say 12v it would produce say 5v. I dont understand how you could regulate down the voltage from 18v to 24v?

Care to explain?
Regads
Ian

[ewan]

Overvolt drillmotors

you can boost the voltage (god knows what its called, but Ill call it a regulator as it does regulate the voltage)

[woody]

Overvolt drillmotors

But the reason I want to overvolt the motors instaid of geting a 12V valve is becaus you will get more power from the drive...correct
...and you need bigger batterys for the same amount of Amps on 12V then on 24V. (weight) Nope ....Dont think so ...V/R = I... Where R is the resistance of your motor.. So your amps pull will double on 24v....So V x I = Watts... Thats approx 4 times the power.

http://ourworld.compuserve.com/homepages/Bill_Bowden/ohmslaw.htm target=_top>http://ourworld.compuserve.com/homep...en/ohmslaw.htm

[glen]

Overvolt drillmotors

as for over volting drill motors ive had my 12 volters running at 24v for over half a year. it uses 95mm wheels with hard plastic tread.

the only time ive blown up the motors is when i put tread on the wheels.... go figure.

it must be said though that the acceleration, power and speed is more than impressive at 24v

[Guest]

Overvolt drillmotors

Weve been running two 14.4v drill motors in our 4 wheel drive for almost a year now - same motors!
Started off at 14.4v battery, but that wasnt fast enough with our 120mm Monster truck tyres, so now running at 18v Technobots Bot-Pack. Had to change the speed controllers to handle the rather large current (skid steer, 4 wheel drive, big fat grippy tyres) to a pair of George Francis H6s. Now get superb speed and control, and the battery lasts more than one fight. Only problem now is getting rid of the heat build-up inside the bot. Should be fitting some fans this weekend.

[Guest]

Overvolt drillmotors

Woody, your right about the fact that the motors use the same amps but the valve and the 24V compressor wont. They will use less. Becaus Im not overvolting them.

And Ewan, do you have al link or somthing like that for the so called booster?

Thanks again

[ewan]

Overvolt drillmotors

http://www.atv-projects.com/html/lnb_voltage_booster.htmlhttp://www.atv-projects.com/html/lnb...e_booster.html
Here is an example of a low voltage booster.

[Guest]

Overvolt drillmotors

Woody, youre correct about that. If you overvolt your motors. The current will increase by the same factor as the voltage, meaning that the total power will be square of the voltage increase.

However, I think he means that everything will use a fixed amount of power. So that when lowering the voltage, you need to use more current to substain the same amount of power.

But why is 24V the goal? If you have 1Ah on 24V or 2Ah on 12V doesnt matter, its all the same amount of energy! But more importantly, the same amount of weight.

For example, imagine that your robot needs a fixed amount of energy to funtion properly during a 5 minute fight. Then it doesnt matter wether thats 24V and 2Ah (which equals 576Wh), or 12V and 4Ah (which also equals 576Wh).

So while a 12V system will use twice the amount of current, itll use half the amount of volts compared to a 24V system (which equals the same energy). So youll carry the same amount of battery anyway.

But if Ive understood correctly, youre also going to power a 24V compressor? Then youre only option will be to go for a 24V battery and lower the voltage for the drive motors. As a voltage booster cant handle the current of a compressor.