Power Functions Alternate Power Supply Methods

[porty6600]

Are there any alternate ways to supply power to PF motors? The battery box is bulky and kind of difficult to install into small machines such as a bike.

Thanks in advance,
porty6600

[mattallen37]

Sure, a 9v battery would work. There is even a lego 9v battery box.

[porty6600]

Thanks. Okay, I picked the one I would like to use, but I wasn't sure if it will power all of the following PF items:
2 M-Motors
1 Set of Lights
1 IR Receiver
1 Control Switch

Thanks, porty6600

[inxt-generation]

Thanks. Okay, I picked the one I would like to use, but I wasn't sure if it will power all of the following PF items:
2 M-Motors
1 Set of Lights
1 IR Receiver
1 Control Switch

Thanks, porty6600

Which did you decide?

[porty6600]

Woops! I meant to post the link! Here it is: http://www.bricklink.com/catalogItem.asp?S=5391-1

[mightor]

Keep in mind that a 9V block battery usually has between 150 and 250 mAh versus about 1500-2500mAh for 6xAA. So your motors won't run for as long as a normal power supply.

- Xander

[porty6600]

Keep in mind that a 9V block battery usually has between 150 and 250 mAh versus about 1500-2500mAh for 6xAA. So your motors won't run for as long as a normal power supply.

- Xander

That does not sound good! What exactly does that mean? The battery life?

[mightor]

Well, think of a mAh (milliamp Hour) of a unit of power capacity. The more units you have, the longer you can provide power. OK, now say you are using a motor that draws 150mA when driving a small motor cycle. If your battery has a capacity of 300mAh, it will theoretically power your motor for 300 mAh/ 150mA == 2 hours. So naturally, if you are using 6x 2100 mAh 1.5V AA batteries, your motor will last 2100 mAh/150mA == 14 hours.

This is theoretical, of course. If you are going the route of the 9V battery block, which is nice and compact and light, I would recommend using rechargeable batteries, or you'll end up spending a fortune on these.

Regards,
Xander

[porty6600]

Well, think of a mAh (milliamp Hour) of a unit of power capacity. The more units you have, the longer you can provide power. OK, now say you are using a motor that draws 150mA when driving a small motor cycle. If your battery has a capacity of 300mAh, it will theoretically power your motor for 300 mAh/ 150mA == 2 hours. So naturally, if you are using 6x 2100 mAh 1.5V AA batteries, your motor will last 2100 mAh/150mA == 14 hours.

This is theoretical, of course. If you are going the route of the 9V battery block, which is nice and compact and light, I would recommend using rechargeable batteries, or you'll end up spending a fortune on these.

Regards,
Xander

Thanks, I think I understand now. Would you still go this route? And I didn't see an answer on my power supply post above your first one.

porty6600

[inxt-generation]

Well, think of a mAh (milliamp Hour) of a unit of power capacity. The more units you have, the longer you can provide power. OK, now say you are using a motor that draws 150mA when driving a small motor cycle. If your battery has a capacity of 300mAh, it will theoretically power your motor for 300 mAh/ 150mA == 2 hours. So naturally, if you are using 6x 2100 mAh 1.5V AA batteries, your motor will last 2100 mAh/150mA == 14 hours.

This is theoretical, of course. If you are going the route of the 9V battery block, which is nice and compact and light, I would recommend using rechargeable batteries, or you'll end up spending a fortune on these.

Regards,
Xander

Thanks, I think I understand now. Would you still go this route? And I didn't see an answer on my power supply post above your first one.

porty6600

You should be fine with that. The recommended rating per battery box by LEGO is: 4 PF M-Motors, or 2 PF XL-Motors. Those ratings take into account powering the IR-Receiver. You should be fine with 2 m-motors and a light. The control switch shouldn't make a difference. Just be aware, as Xander said, that a 9-volt box battery won't last as long as 6 double or triple a.