Voltage or Amperage?

[darkred87T]

Just wondering. My brother bought an R/C boat for his son and they frequent the local lake with it. Well, recently, I decided to buy one and have some fun too. When I got the boat, I quickly realized that it wasn't fast enough for my liking so I rigged up a series circuit with enough plugs to daisy chain two batteries intstead of one to the little electric motor. It worked awesome for a while until I burned it up. I'm thinking about purchasing an electric motor for it that can handle the power of two batteries. Before I do though, I'm trying to find out what specs to look for as far as what I want it to do. The guy at the hobby shop told me once that a parallel circuit will increase amperage and a series circuit, (like I have) will increase voltage when supplying more power. Should the new motor be able to handle more amperage or more voltage in this situation?

 

[UNGN]

DC motors have a given RPM per volt.

Double the voltage, you'll double the RPM.

If you double the RPM, the amps used by the motor might quadruple, because amps used are related to how much a motor is held back.

If a motor wants to go 30,000 RPM and you let it go 30,000 RPM, it may use only one amp.

If the motor wants to go 30,000 RPM and you hold it back to 10,000 RPM with a load, it may use 40 amps.

Hold it back to 100 RPM, it may use 90 amps before it melts.

Motors will burn out from excess RPM, too so too much volts can damage a motor from just spinning it too fast.

 

[darkred87T]

Thanks, I think my old motor burned out because it was only a 6volt motor and I was putting 14.4 volts (2 7.2 volt battery packs) through it. The new motor I am looking to buy is rated at 14.4 volts so I shouldn't have a problem running it with the two batteries putting out 7.2 volts.

 

[NM Tom]

If your 2 batteries were wired in series then you did double the voltage but did not increase the availble current. If wired parallel then voltage would have stayed at 7.2 volts but available current would have doubled.

 

[darkred87T]

That's what I thought. I don't want to kill my new motor but it sounds like it shold be O.K.

 

[rodman99999]

Keep in mind: If the motor is rated to run a certain RPM and torque at a given voltage/amperage- it will run slower/with less power at a lower voltage/amperage. You'd be better served by a motor rated for what your batteries are actually putting out.

 

[UNGN]

putting 2 battery packs in parallel will double the amp hours (roughly the run time) of a motor, but it won't double the amperage a motor sees.

The load on the motor determines how many amps it sees.

Runing a 100 amp hr battery won't cause any more strain on a motor (except for the added weight of the batteries) than a 4 amp hr battery pack.

If the motor is a 550 sized motor, the all electronics DCM-231 is a great motor for about $4.00, that will handle 14.4 volts with no problems.

 

[darkred87T]

putting 2 battery packs in parallel will double the amp hours (roughly the run time) of a motor, but it won't double the amperage a motor sees.

The load on the motor determines how many amps it sees.

Runing a 100 amp hr battery won't cause any more strain on a motor (except for the added weight of the batteries) than a 4 amp hr battery pack.

If the motor is a 550 sized motor, the all electronics DCM-231 is a great motor for about $4.00, that will handle 14.4 volts with no problems.

Thanks,
I'll check it out. However, I burned up a 600 motor.