overclocking a 12V DC motor

Using Arduino Motors, Mechanics, Power and CNC
1

Hi…

I wonder if you could help with the following problem.

I have a 12V automotive DC washer pump motor.
I has the following specs.

at 14.2V 7.2 A initial current draw,
4A continuous current draw.
produces 42 psi.

i wish to overdrive the pump to a higher voltage to get more output.
I tried a 15.2 V power supply and got 50psi.

i want to probably go up to 20V input but i am unsure of the current draw at this level and i want to get a boost converter that can do this.

Will a 10 A output boost converter be enough or should i get a higher Amp output say 15A

Im a bit of a noob with this with limited equipment so any help i can get will be great..

regards Steve

2

ssgoulash:
i want to probably go up to 20V input but i am unsure of the current draw at this level and i want to get a boost converter that can do this

The only way to determine the current draw at 20v is to measure it.

If the motor is designed for 12v there must be good likelihood that the smoke will escape if you drive it with 20v for any length of time.

With a higher voltage there will be a higher current causing more heating in the coils and more wear on the armature.

Also you need to be aware that the startup and stall current is always a lot greater than the running current of an electric motor. You power supply must be able to provide the startup current. Lead-acid batteries are good at that.

If this project is anything more than a toy just get a motor and pump with the correct specification.

...R

3

Hi ssgoulash,

Like Robin said running motors above their rated voltage is usually bad for the motor. What is it you are trying to achieve? Maybe tell a bit more about your project so we can have some context.
If you want to achieve higher pressure there may be different options.

Kind regards,
Teunman

4

Hi there!

If you want to overdrive the motor for a small percentage of your system operation, it should be okay, provided that the power supply(ies) can source that much. If you want to overdrive for extended periods and/or a large percentage of the system operation, you should look at getting a different motor that is rated for the higher voltage/current that you would like to see.

5

Simple thing. If your 12 V motor would be fine with 20 V, it wouldn't be a 12 V motor, but a... let's see... a 20 V motor.

6

There are at least three problems that happen as you increase the drive voltage / motor speeds:

Faster speed causes accelerated wear of the bearings (shortens life) - beyond a certain speed
the bearings might overheat and sieze/fail. Typically only an issue for fast motors

Higher currents cause overheating and burning out of windings, and overheating/arcing of
the commutator. Often commutator destruction is the ultimate failure mechanism.

Beyond a safe limit speed the rotor may explode violently (very unlikely with small hobby motors, but
a devastating failure mode in large series-wound motors).

The second of these can also happen from stalling/overloading of the motor at nominal voltage.