DLuders

Power Functions ADAPTER for 9V Battery Use

27 posts in this topic

On this Eurobricks post, one can see a Power Functions (PF) adapter (made by NewBatteryGuy) that allows one to connect a PF Receiver directly to a 9V battery. His video talks about Lego PF TRAINS, but the same adapter could be very useful for PF TECHNIC creations. A picture of it appears below. "It's an adapter that connects the Lego infrared receiver to a 9v battery. It's very handy because it replaces the 50 dollar rechargeable battery box from Lego. Instead you can buy this adapter and a 5 dollar rechargeable 9V battery."

IMAG0066.jpg

http://www.youtube.com/watch?v=WhjZoymaYkY

Philo's Lego 9V Technic Motor Comparison page shows that the 9V PF Train Motor has a no-load current of 90 mAH. The PF Medium Motor has a no-load current of 60 mAH, and the PF XL Motor has a no-load current of 80 mAH (both less than the PF Train Motor).

The STALLED CURRENT for the PF Train Motor is 1.3 Amps (higher than the PF Medium Motor's 850 mA, but less than the PF XL Motor's 1.8 Amps). NewBatteryGuy stated on his YouTube video description that a "250 mAh Battery Lasted 1 Hr 20 Min at speed 2. Over 30 Mins at full speed. So, one could conclude that since the PF Train Motor draws more current than the PF Medium motor, that one could run a PF Medium Motor for WELL OVER 30 minutes.

I know that 30 minutes is not a long time, but how many minutes do you actually "play" with your MOC? 5 minutes? Think of all of the small PF cars one could make if the BATTERY were small.... :look:

rpf-train-t.jpgrpf-med-t.jpgMH9V250.jpg

Edited by DLuders

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It is possible to do it the lego way: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=4495832 (the connectors on top of the the battery contain the classical 'short' between gnd-C1, 9V-C2) This allows the use of an old 9V battery box with the PF receiver.

A little bit cramped but works: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=4495840 (the battery box occupies the space reserved for the train weights)

I also use this trick to power bigger locomotives from old 9V AA battery boxes. (this means it is possible to have 5000 mAh of battery capacity in a locomotive and with cheap recharagable AA batteries)

just my 2 cents...

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ok, I need to power quite a lot of engines and I'm asking the experts now...

it doesn't matter to me if the battery will last for less time, when you have 5 or 6 spares, you also have time to recharge the empty ones while using the full ones.

my worry is if this scenario is going to damage the motors.

thank you in advance for your replies

have a nice train lego day

mrBlue

edit: spelling check

Edited by mrblue

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ok, I need to power quite a lot of engines and I'm asking the experts now...

it doesn't matter to me if the battery will last for less time, when you have 5 or 6 spares, you also have time to recharge the empty ones while using the full ones.

my worry is if this scenario is going to damage the motors.

thank you in advance for your replies

have a nice train lego day

mrBlue

edit: spelling check

As long as you do not go over-voltage the motors will be fine, in fact 9V rechargable batteries are 7.2V so over-voltage is not a problem at all. :wink:

Brick On Power On ! :grin:

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As long as the motors don't stall, it's all right.

it would be nice to know before the motor stalls or get damaged...

anyway, thank you lightningtiger for your help

have a nice lego day

mrBlue

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I personally own three of the Power Functions Adapters, and they work great. :thumbup: You just cannot get any more compact and lightweight than a 9V battery + adapter. There are many tiny Lego MOCs that now can be motorized (and not have to lug around a big battery box). I placed one inside a Lego tank that did not have much room, and performance of the tank improved due to the decreased weight.

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Durability tip:

Do never deplete your rechargeable batteries completely, this will damage them. In fact, one should stop when voltage drops below approx. 1V per cell (Ni-CD and Ni-MH; one will notice a performance drop also).

Some cells contain less energy than others, these will be first depleted. If these cells are kept in use, current will flow "the wrong way" through these depleted cells: They should now be recharged, but instead get even more used up by the wrong current.

So, if you like your rechargeable batteries, change them in time :)

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Mmh, 9 $ for one of them?!

I think it's cheaper to buy a LEGO-wire and a 9V battery-clip, like this one:11445.jpg

Open the LEGO-Brick, put the battery-clip in and its done.

So I think the LEGO-wire is about 4 $, the battery-clip is about 0,40 $ and some minutes of work.

Regards

Max

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It is possible to do it the lego way: http://www.brickshelf.com/cgi-bin/gallery.cgi?i=4495832 (the connectors on top of the the battery contain the classical 'short' between gnd-C1, 9V-C2) This allows the use of an old 9V battery box with the PF receiver.

I do not understand what has been done in that photo.

I've tried powering up a PF IR receiver with a non-pf battery box, but it doesn't work.

Could you please explain which of the 4 wires should be connected on the PF plug in order for it to work with a 9v-type battery box. Also, how has this been done on the photo?

Thanks

Edited by le60head

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I do not understand what has been done in that photo.

I've tried powering up a PF IR receiver with a non-pf battery box, but it doesn't work.

Could you please explain which of the 4 wires should be connected on the PF plug in order for it to work with a 9v-type battery box. Also, how has this been done on the photo?

Thanks

Perhaps the information on Philo's site might help you: http://www.philohome.com/pf/pf.htm (look about 2/3 down that page)

It looks like the two outside wires provide the +9V and 0V (ground) lines.

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It looks like the two outside wires provide the +9V and 0V (ground) lines.

Yes, the IR receiver does get its supply from the outer wires of PF cable. Just make sure not to reverse polarity!

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I saw the explanations on Philo's website.

I've found tons of very useful information on that site.

Wanted to say a BIG Thank You for that :)

Since i'm not that familiar with electrics, i'd be happy if someone could post a graphic on how to wire a 9v to pf power adaptor.

Best Regards,

legohead

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I'd bought a couple of these via the Bricklink store. Although I would have no issues to make these myself, it was more a cost vs time decision (I had no time). The end result is pretty good, although the tight junction to the 9V battery means you often fear ripping the plug off.

Because the two lines C1 and C2 are not connected, the power supply wont switch on a PF light. First the connector must be fed through a PF IR receiver in order to generate the correct control lines.

A 9V battery is too wide to fit into a 2stud gap; it ideally needs 3 studs to lay lengthwise. I modified some 4512 locomotives to do this; and it works well. In the tests I did (somewhere on this forum) the 9V lasted for about 1.8 hours continuous use pulling a set of 4-5 12V carts.

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Because the two lines C1 and C2 are not connected, the power supply wont switch on a PF light.

But there is no problem connecting them too... this way a PF light or a motor could be run directly off battery (preferably with a polarity switch inserted to avoid need of disconnecting the battery or the device)

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I'm sorry to revive this old topic, but I wanted to know if this is still available for sale. I clicked the buy now on the blog and it said there was a problem and that I had to contact the seller. Unfortunately I do not know how to contact this person. In addition, the bricklink link is also dead. Can anyone help me, please?

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Yes, you can still get these adapters. They are available from LEGO Education or from Bricklink. I think you can still get them from Shop @ Home as well.

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Where on bricklink can I get them? I can't seem to find the store that sells these. I would just make them myself, but I'm not sure I completely understand how it's done.

Edited by Legoroni

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Oh, ok. To make one, I think I need the battery holder and that connector piece you just posted. Do I just connect the battery holder wire to the brick? Or is it more complicated than that?

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It is possible to do it the lego way: http://www.brickshel...y.cgi?i=4495832 (the connectors on top of the the battery contain the classical 'short' between gnd-C1, 9V-C2) This allows the use of an old 9V battery box with the PF receiver.

A little bit cramped but works: http://www.brickshel...y.cgi?i=4495840 (the battery box occupies the space reserved for the train weights)

I also use this trick to power bigger locomotives from old 9V AA battery boxes. (this means it is possible to have 5000 mAh of battery capacity in a locomotive and with cheap recharagable AA batteries)

just my 2 cents...

Can you tell me more detail about lego way to use 9v battery?

Edited by mikezang

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It's VERY easy ... you need the following (all are standard Lego items):

- old 9V battery box

- adapter cable (from 9V to PF connectors)

Now, with above setting, you can power any PF motor (or light) directly (you can also ise a switch/polarity inverter).

If you want to use a remote receiver in between, there is one additional detail: The 9V powering the motors/lamps are fed through the inner two wires of the PF connector. The outer 2 wires are for powering the PF remote receiver. To energize the receiver, you need to provide power to the outer wires. This can be easily done by connecting wires 1/3 together, and wires 2/4 together. To do this, you need to inseert small pieces of aluminum foil in between 2 PF connectors.

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It's VERY easy ... you need the following (all are standard Lego items):

- old 9V battery box

- adapter cable (from 9V to PF connectors)

Now, with above setting, you can power any PF motor (or light) directly (you can also ise a switch/polarity inverter).

If you want to use a remote receiver in between, there is one additional detail: The 9V powering the motors/lamps are fed through the inner two wires of the PF connector. The outer 2 wires are for powering the PF remote receiver. To energize the receiver, you need to provide power to the outer wires. This can be easily done by connecting wires 1/3 together, and wires 2/4 together. To do this, you need to inseert small pieces of aluminum foil in between 2 PF connectors.

Is this correct in picture? do you mean that?

post-85795-0-61354800-1393856731_thumb.jpg

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Yes, that looks right. You can just insert small/tiny pieces of aluminum foil in between the two connectors. Make sure the aluminum foil is small enough so you do not short any other connections.

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