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Electronics => Electronics => Topic started by: cooldog on November 08, 2007, 11:20:18 AM

Title: bigger batteries = more power?
Post by: cooldog on November 08, 2007, 11:20:18 AM
i am useing 4AA batteries to control my servos but if i use more volts will the servos be  stronger/faster ??? :'( ???
Title: Re: bigger batteries = more power?
Post by: bukowski on November 08, 2007, 01:20:57 PM
Yes and no. Faster, yes, but weaker.
 It is OK to drive a motor at over-voltage (as long as it's not too much). You gain the benefit of greater motor speed, but you get less torque out of the motor (EG if you doubled the voltage thus doubling the motor speed, you half the torque) The stall current increases propotionally with the motor speed.
Also, when you double the voltage, you are at risk of quadrupling the heat generated in the motor and circuit, leading to a meltdown of your system.

-Buk
Title: Re: bigger batteries = more power?
Post by: cooldog on November 08, 2007, 09:20:55 PM
okay but does my reciver contol current to my servos
 
Title: Re: bigger batteries = more power?
Post by: ed1380 on November 08, 2007, 11:25:55 PM
servos have little circuitry inside, so doing over voltage will fry them
Title: Re: bigger batteries = more power?
Post by: frank26080115 on November 09, 2007, 12:08:43 AM
Yes and no. Faster, yes, but weaker.
 It is OK to drive a motor at over-voltage (as long as it's not too much). You gain the benefit of greater motor speed, but you get less torque out of the motor (EG if you doubled the voltage thus doubling the motor speed, you half the torque) The stall current increases propotionally with the motor speed.
Also, when you double the voltage, you are at risk of quadrupling the heat generated in the motor and circuit, leading to a meltdown of your system.

-Buk

Hey are you sure that's right? I could swear torque have never decreased in any of my motors before when I upped the voltage.
Title: Re: bigger batteries = more power?
Post by: nottoooily on November 09, 2007, 01:09:25 AM
Yes and no. Faster, yes, but weaker.
 It is OK to drive a motor at over-voltage (as long as it's not too much). You gain the benefit of greater motor speed, but you get less torque out of the motor (EG if you doubled the voltage thus doubling the motor speed, you half the torque) The stall current increases propotionally with the motor speed.
Also, when you double the voltage, you are at risk of quadrupling the heat generated in the motor and circuit, leading to a meltdown of your system.

-Buk

No offence, but that's a load of bollocks.

Except the last sentence about overheating. That's usually the limiting factor which prevents you overvoltaging a motor in the first place. You're right that the voltage itself isn't a problem (insulation won't break down until it's much higher), rather it's the extra heating caused by the extra current caused by the extra voltage.

But to the OP, yes you can increase performance but you'll have to worry about both the motor and the electronics, either of which could fail. If you don't care about reliability and destroying them, the best way is crank it up and see what happens, if you do care, that's what data sheets are for :P

Title: Re: bigger batteries = more power?
Post by: Admin on November 09, 2007, 07:57:45 AM
4AA is about 4.8V

You can use 5AA to get 6V without any problem. Above that and you will get overheating problems.

Increasing voltage increases both torque and rpm.

bukowski, you got confused with gearing, which trades torque for rpm :P
Title: Re: bigger batteries = more power?
Post by: ed1380 on November 09, 2007, 06:05:12 PM
if you add more voltage rpm and torque will increase

if voltage stays the same, but you use gearing to increase rpm 2x then torque is 2x weaker
Title: Re: bigger batteries = more power?
Post by: bukowski on November 14, 2007, 11:18:46 AM
whoops, i went back and reread that chapter. Im an idiot, disregard everything i've said.
Title: Re: bigger batteries = more power?
Post by: Jdog on March 29, 2009, 11:28:07 AM
4AA is about 4.8V

You can use 5AA to get 6V without any problem. Above that and you will get overheating problems.

Increasing voltage increases both torque and rpm.

bukowski, you got confused with gearing, which trades torque for rpm :P
Isn't 4 AA 6 volts unless they are rechargeable? I use 4 AA and I get 6 volts.
Title: Re: bigger batteries = more power?
Post by: offy on March 29, 2009, 11:40:55 AM
4AA is about 4.8V

You can use 5AA to get 6V without any problem. Above that and you will get overheating problems.

Increasing voltage increases both torque and rpm.

bukowski, you got confused with gearing, which trades torque for rpm :P

4AA normal batteries are 6v
4 cells are 4.8 volts (Thats why 6v rechargeable batteries have 5 cells)
Title: Re: bigger batteries = more power?
Post by: superchiku on March 29, 2009, 01:38:30 PM
dnt give more than 7.2v they willfry.. . .
Title: Re: bigger batteries = more power?
Post by: SmAsH on March 29, 2009, 02:26:57 PM
yup, servos cant take more than 7.2 normally. and is there a reason this was resurrected?
Title: Re: bigger batteries = more power?
Post by: Jdog on March 29, 2009, 07:38:20 PM
yup, servos cant take more than 7.2 normally. and is there a reason this was resurrected?
I'm stupid :D
Title: Re: bigger batteries = more power?
Post by: Admin on April 08, 2009, 12:53:10 AM
4AA is about 4.8V

You can use 5AA to get 6V without any problem. Above that and you will get overheating problems.

Increasing voltage increases both torque and rpm.

bukowski, you got confused with gearing, which trades torque for rpm :P
Isn't 4 AA 6 volts unless they are rechargeable? I use 4 AA and I get 6 volts.
1.2 volt for NiMH cells, 1.5 volt for alkaline cells