Answers.Body: <p>I performed my own tests with:</p>
  
  <ul>
  <li>battery boxes: <em>old</em> 9V and <em>new</em> Power Functions</li>
  <li>motors: <em>old</em> 9V and <em>new</em> XL</li>
  <li>the <a href="http://www.bricklink.com/v2/catalog/catalogitem.page?id=77442" rel="nofollow noreferrer">8886 cable</a></li>
  <li>one <a href="http://www.bricklink.com/v2/catalog/catalogitem.page?P=4757&amp;idColor=1" rel="nofollow noreferrer"><em>electric</em> plate (4757)</a> (required since the connectors of the 9V motor are on the bottom while the 8886 cable connects from top)</li>
  <li>2 grey <a href="http://www.bricklink.com/v2/catalog/catalogitem.page?P=2952&amp;idColor=9" rel="nofollow noreferrer"><em>Propeller 2 Blade 9 Diameter</em> (2952)</a> in order to show the rotation of motors</li>
  </ul>
  
  <hr>
  
  <p>Here are the results: <strong>it works in both ways with motors and battery boxes</strong>.</p>
  
  <p><em>Old</em> <strong>9V</strong> motor powered by <em>new</em> <strong>Power Functions</strong> battery box, with the 8886 cable plugged to the motor through the electric plate:</p>
  
  <p><a href="https://i.sstatic.net/7wUXG.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/7wUXGm.jpg" alt="enter image description here"></a></p>
  
  <p>(the cable is out of the photo frame but I guarantee that there's no trick)</p>
  
  <p><em>New</em> <strong>XL</strong> motor powered by <em>old</em> <strong>9V</strong> battery box:</p>
  
  <p><a href="https://i.sstatic.net/UbiP2.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/UbiP2m.jpg" alt="enter image description here"></a></p>
  
  <p>As you can see, the connectors of the 8886 cable have different colors, the 9V-side is a lighter grey.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-08-23T20:29:47.850Z
Answers.LastActivityDate: 2016-08-26T13:23:14.953Z
Answers.LastEditDate: 2016-08-26T13:23:14.953Z
Answers.UserDisplayName: A.L
Answers.Body: <p>According to <a href="http://shop.lego.com/en-GB/LEGO-Power-Functions-Extension-Wire-8886#BVRRDisplayContentTitleID" rel="nofollow"><em>Customer reviews</em> on the official website</a>, this cable enable powering motors in both ways between <em>old</em> and <em>new</em> power functions versions:</p>
  
  <hr>
  
  <blockquote>
    <p>This cable allows you to power the new 9v motors from the old 9v system or vise versa..</p>
  </blockquote>
  
  <p>Author: heavyD.</p>
  
  <hr>
  
  <p>But there is an incompatibility between the old battery boxes and the IR receivers:</p>
  
  <blockquote>
    <p>This cable also powers new motors from the old battery box, but it cannot power an IR receiver, which requires the new battery box and all 4 wires of the new cable. (This cable only converts the 2 motor-powering wires.)</p>
  </blockquote>
  
  <p>Author: Technic010.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-08-06T17:48:30.997Z
Answers.LastActivityDate: 2016-08-06T17:56:22.543Z
Answers.LastEditDate: 2016-08-06T17:56:22.543Z
Answers.UserDisplayName: A.L
Answers.Body: <p>Power functions has four wires, "Electric system 9V" only had two. Two wires carry the motor control lines. The other two wires carry a power supply which is fixed polarity, never speed controlled and is not switched by the IR receiver (though it is switched by the switch on the battery box). The adapter cable connects the two wires of the Electric system 9V to the two motor control lines of the power functions.</p>
  
  <p>Things that will definitely work:</p>
  
  <ul>
  <li>Powering any "Electric system 9V" kit from a power functions power source/controller. Some of the Early kit will require use of an Electric plate or an old style cable because it has it's contacts on the bottom.</li>
  <li>Powering an ordinary power functions motor or a set of power functions lights from an "Electric system 9V" power source/controller.</li>
  </ul>
  
  <p>Things that definitely won't work.</p>
  
  <ul>
  <li>Powering a power functions IR receiver from an "Electric system 9V" power source.</li>
  <li>Powering the power functions servo motor from an "Electric system 9V" source.</li>
  </ul>
  
  <p>Things I can't find enough information on.</p>
  
  <ul>
  <li>How the power functions switch behaves. In particular whether it draws it's input power from the fixed-polarity lines (which would make it incompatible with "Electric system 9V" power sources) or from the motor lines (which would make it compatible with "Electric system 9V" power sources).</li>
  </ul>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-09T08:47:31.280Z
Answers.Text: Actually there IS a way to power IR Receiver/Servo motor from an old 9V power source - daisy-chain them to a new (empty) battery box, switched to the correct position (can't remember which one) - that way the switch in the battery box powers the power supply lines as well. Maico Arts uses that trick to power his servo-motor GBC modules, for example
Answers.UserDisplayName: Joubarc
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-09T13:06:09.557Z
Answers.Text: mmm, just be careful about polarity....
Answers.UserDisplayName: Peter Green
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-10T14:54:19.283Z
Answers.Text: Yes, definitely - I didn't emphasize this enough with "switched to the correct position"
Answers.UserDisplayName: Joubarc
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-05-22T13:35:38.003Z
Answers.Text: The thing is the "correct position" depends on how the adapter cable is connected to the electric system 9V source, and what output polarity the electric system 9V source is set to.
Answers.UserDisplayName: Peter Green
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-05T17:10:20.213Z
Answers.LastActivityDate: 2018-01-07T23:59:48.903Z
Answers.LastEditDate: 2018-01-07T23:59:48.903Z
Answers.UserDisplayName: Peter Green
Body: <p>Here is the LEGO "LEGO® Power Functions Extension Wire" (8886):</p>
  
  <p><a href="https://i.sstatic.net/roUjJ.jpg" rel="noreferrer"><img src="https://i.sstatic.net/roUjJm.jpg" alt="enter image description here"></a></p>
  
  <p>We can see that the left connector can connect to <em>old</em> 9V electric bricks or wires and the right connector can be plugged to the <em>new</em> Power Functions connectors.</p>
  
  <p>The <a href="http://shop.lego.com/en-CA/LEGO-Power-Functions-Extension-Wire-8886" rel="noreferrer">LEGO website</a> gives this description:</p>
  
  <blockquote>
    <p>Power up your LEGO® Power Functions creations with this 8" extension
    wire. Make your models bigger, better, and more mechanized than ever
    before!</p>
    
    <ul>
    <li><strong>Allows you to connect your LEGO 9V electric systems to the new Power Functions!</strong></li>
    <li>Extension Wire is 8" (20cm) long</li>
    </ul>
  </blockquote>
  
  <p>(emphasis mine)</p>
  
  <p>Does this cable work in both directions?</p>
  
  <ul>
  <li>Can it power a <em>new</em> <em>Power Functions</em> motor from an <em>old</em> battery box?</li>
  <li>Can it power an <em>old</em> motor from a <em>new</em> <em>Power Functions</em> battery box?</li>
  </ul>
  
  <p>Do switches like the <a href="http://www.bricklink.com/v2/catalog/catalogitem.page?P=6551c01" rel="noreferrer"><em>old</em> one</a> or <a href="http://brickset.com/sets/8869-1/Polarity-Switch" rel="noreferrer"><em>new</em> one</a> let you control <em>new</em> and <em>old</em> motors respectively?</p>
  
Tags: <technic><motor><power-functions>
Title: Does the LEGO "Power Functions Extension Wire" (8886) work in both directions between old 9V and new Power Functions devices?
UserDisplayName: A.L
ThreadText: # Does the LEGO "Power Functions Extension Wire" (8886) work in both directions between old 9V and new Power Functions devices?
  
  (Asked by: username_0 on 2016-08-06)
  
  Here is the LEGO "LEGO® Power Functions Extension Wire" (8886):
  
  [![enter image description here](https://i.sstatic.net/roUjJm.jpg)](https://i.sstatic.net/roUjJ.jpg)
  
  We can see that the left connector can connect to *old* 9V electric bricks or wires and the right connector can be plugged to the *new* Power Functions connectors.
  
  The [LEGO website](http://shop.lego.com/en-CA/LEGO-Power-Functions-Extension-Wire-8886) gives this description:
  
  > Power up your LEGO® Power Functions creations with this 8" extension
  > wire. Make your models bigger, better, and more mechanized than ever
  > before!
  >
  > * **Allows you to connect your LEGO 9V electric systems to the new Power Functions!**
  > * Extension Wire is 8" (20cm) long
  
  (emphasis mine)
  
  Does this cable work in both directions?
  
  * Can it power a *new* *Power Functions* motor from an *old* battery box?
  * Can it power an *old* motor from a *new* *Power Functions* battery box?
  
  Do switches like the [*old* one](http://www.bricklink.com/v2/catalog/catalogitem.page?P=6551c01) or [*new* one](http://brickset.com/sets/8869-1/Polarity-Switch) let you control *new* and *old* motors respectively?
  
  **Tags:** technic, motor, power-functions
  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_0 on 2016-08-23. Score: 4 | Accepted answer
  
  I performed my own tests with:
  
  * battery boxes: *old* 9V and *new* Power Functions
  * motors: *old* 9V and *new* XL
  * the [8886 cable](http://www.bricklink.com/v2/catalog/catalogitem.page?id=77442)
  * one [*electric* plate (4757)](http://www.bricklink.com/v2/catalog/catalogitem.page?P=4757&idColor=1) (required since the connectors of the 9V motor are on the bottom while the 8886 cable connects from top)
  * 2 grey [*Propeller 2 Blade 9 Diameter* (2952)](http://www.bricklink.com/v2/catalog/catalogitem.page?P=2952&idColor=9) in order to show the rotation of motors
  
  ---
  
  Here are the results: **it works in both ways with motors and battery boxes**.
  
  *Old* **9V** motor powered by *new* **Power Functions** battery box, with the 8886 cable plugged to the motor through the electric plate:
  
  [![enter image description here](https://i.sstatic.net/7wUXGm.jpg)](https://i.sstatic.net/7wUXG.jpg)
  
  (the cable is out of the photo frame but I guarantee that there's no trick)
  
  *New* **XL** motor powered by *old* **9V** battery box:
  
  [![enter image description here](https://i.sstatic.net/UbiP2m.jpg)](https://i.sstatic.net/UbiP2.jpg)
  
  As you can see, the connectors of the 8886 cable have different colors, the 9V-side is a lighter grey.
  
  
  ---
  
  ### Answer by username_0 on 2016-08-06. Score: 4
  
  According to [*Customer reviews* on the official website](http://shop.lego.com/en-GB/LEGO-Power-Functions-Extension-Wire-8886#BVRRDisplayContentTitleID), this cable enable powering motors in both ways between *old* and *new* power functions versions:
  
  ---
  
  > This cable allows you to power the new 9v motors from the old 9v system or vise versa..
  
  Author: heavyD.
  
  ---
  
  But there is an incompatibility between the old battery boxes and the IR receivers:
  
  > This cable also powers new motors from the old battery box, but it cannot power an IR receiver, which requires the new battery box and all 4 wires of the new cable. (This cable only converts the 2 motor-powering wires.)
  
  Author: Technic010.
  
  
  ---
  
  ### Answer by username_1 on 2018-01-05. Score: 1
  
  Power functions has four wires, "Electric system 9V" only had two. Two wires carry the motor control lines. The other two wires carry a power supply which is fixed polarity, never speed controlled and is not switched by the IR receiver (though it is switched by the switch on the battery box). The adapter cable connects the two wires of the Electric system 9V to the two motor control lines of the power functions.
  
  Things that will definitely work:
  
  * Powering any "Electric system 9V" kit from a power functions power source/controller. Some of the Early kit will require use of an Electric plate or an old style cable because it has it's contacts on the bottom.
  * Powering an ordinary power functions motor or a set of power functions lights from an "Electric system 9V" power source/controller.
  
  Things that definitely won't work.
  
  * Powering a power functions IR receiver from an "Electric system 9V" power source.
  * Powering the power functions servo motor from an "Electric system 9V" source.
  
  Things I can't find enough information on.
  
  * How the power functions switch behaves. In particular whether it draws it's input power from the fixed-polarity lines (which would make it incompatible with "Electric system 9V" power sources) or from the motor lines (which would make it compatible with "Electric system 9V" power sources).
  
  > **Comments:**
  > **username_2**: Actually there IS a way to power IR Receiver/Servo motor from an old 9V power source - daisy-chain them to a new (empty) battery box, switched to the correct position (can't remember which one) - that way the switch in the battery box powers the power supply lines as well. Maico Arts uses that trick to power his servo-motor GBC modules, for example  
  > **username_1**: mmm, just be careful about polarity....  
  > **username_2**: Yes, definitely - I didn't emphasize this enough with "switched to the correct position"  
  > **username_1**: The thing is the "correct position" depends on how the adapter cable is connected to the electric system 9V source, and what output polarity the electric system 9V source is set to.  
  
  ---
  
  