Powered Up Lithium DIY

[Hod Carrier]

Alternatively you could simply solder a PP3 battery connector onto the opposite end of the PF power lead, being careful to correctly observe polarity as described above. This was the technique used for the now seemingly defunct MiniZip cable. The required space for the PP3 battery with connector and cable running over the top has a footprint of 4x7 studs and a height of 7 plates.

[dr_spock]

I use DuPont style connectors.  That way I can flip polarity around if needed or mix and match adapters for experimentation.

[UltraViolet]

3 hours ago, 1963maniac said:

Thanks for the great explanation. Much appreciated!! So, would you please explain the modified PF cable too. (some of us aren't such good electricians)

  I will try to make an actual image of the fabrication when I get a chance.  I didn't have enough time last night when I wrote the procedure in text form.

8 hours ago, dtomsen said:

But wouldn't the 9v to PF wire solve the polarity issues?

  You are certainly correct that the cable can be oriented one way or another on the stud connectors in order to get the polarity for the PF output correct, and I described those forward and reverse polarity orientations in my explanation. I have tried to keep the explanation as simple as possible (and at lowest risk) for those of us that "aren't such good electricians", and because it was not easy weeding out wrong information from the internet.  The 9V stud system doesn't have a fixed polarity, but it does in a sense have a 'preferential' forward polarity.  The trouble, particularly for the inexperienced or those without the benefit of owning a multimeter to check, is that you have to be aware at all times what polarity any 9V studded connection is actually creating, as it's not marked on any of the components, and is potentially subject to reversal at any connection point.  (There are multiple ways to easily create a dead short solely within the 9V studded environment.)  The PF/9V combo connector will not automatically solve this for you.

  Unless you want to have to make all your 9V studded connections by trial an error, or marking labels on everything, it is better to understand the existing polarity of all the components involved and get it right the first time.  The PF system expects only ever one polarity on the battery wires - once you start injecting power from C1/C2 and crossing it back over to the battery lines, you have to get this correct every time.  I don't know if all the PF components have integrated reverse polarity protection on the battery lines (which should not have been necessary given their implementation), and I don't intent to find out by frying something at random, or worse, by having someone else fry something at random because I encouraged them to try.  (The 9V studded battery boxes have overcurrent protection in case of a dead short, but don't tempt fate by engaging it.)  The PF system enforced a safe connection every time by making it impossible to connect the PF battery wires to the 9V studded legacy contacts, only to the C1/C2 contacts.  Once you go circumventing this restriction, the onus is on you to keep track of the polarity.  C1/C2 you can reverse all day long and it doesn't matter, but under normal circumstances you shouldn't need to reverse the expected polarity of the PF battery lines, and giving that ability is confusing without clear polarity markings/colors on your modified connectors.

  I appreciate everyone's creativity with alternative connectors in their cable mods, and it's certainly something I know how to do.  My explanation above simply allowed use of all standard LEGO components/connectors, while only having to modify one part (the wire), and not having to add anything else.  It is the simplest way and safest way.

P.S.  Had LEGO gone with a reversable PF connector with five contacts instead of four, this all could have been avoided because it would have allowed them to preserve battery polarity in either orientation.  The center pin would be ground and the one pin to either side of center would both be 9V positive fixed.  The outer two would be C1 and C2 which would then be reversable.  As they did not go that route, we have to pay attention to polarity ourselves.

[1963maniac]

On 3/3/2021 at 11:35 AM, UltraViolet said:

  I will try to make an actual image of the fabrication when I get a chance.  I didn't have enough time last night when I wrote the procedure in text form.

Looking forward to that.

Is this what you were talking about?

 

Edited March 5, 2021 by 1963maniac
added content

[XG BC]

They (or atleast the version 1 powerfunctions receiver) dont have any reverse polarity protection on the two outer lines. I fount that out when i managed to fry 2 of these receivers i  a row because i have accidently connected them backwards. The weird thing is that the receiver part of these still works but the motor controll chip is dead.

XG BC

Edited March 5, 2021 by XG BC

[UltraViolet]

On 3/5/2021 at 12:04 PM, XG BC said:

They (or atleast the version 1 powerfunctions receiver) dont have any reverse polarity protection on the two outer lines. I fount that out when i managed to fry 2 of these receivers i  a row because i have accidently connected them backwards. The weird thing is that the receiver part of these still works but the motor controll chip is dead.

XG BC

  Thank-you for recounting your experiences.  While unfortunate, they at least illustrate precisely the reason why I was trying to have everyone err on the side of caution.  I see in the image linked to by 1963maniacs a V2 receiver that appears to have battery source connected in via one of the motor outputs.  I can't see properly from the angle in the photo, but let's go with this premise for the moment to explore what would happen.  If this were just a pure PF setup, that would work safely, because the PF battery lines are simply connected through internally between the receiver input and both output connectors.  In that way, the receiver doesn't know the difference, and you could get away with still using the occupied output port by stacking.

  If, however, setting up as seemed to be shown in that photo and as per our premise, what then is happening is battery supply voltage is only passing through the C1/C2 lines backwards into the actual motor controller PWM output driver circuit on one port.  For some reason this seems to actually work on my V1 receiver (with either polarity) for a motor connected to the remaining port, but I can't imagine it's a safe condition to create, particularly if you accidentally activate the first reverse-fed output from the remote, plus it also wastes a port.  If Philo is reading this, I would very much appreciate his assessment of the risk and what is actually going on in the circuitry when you attach this way, and whether or not there was any difference in this regard between V1 and V2 receivers.  My recommendation is to not do it like this.  I've certainly never heard of it being an officially intended configuration.

  I will illustrate the cable modification technique some time this weekend.  Unfortunately I was occupied with an urgent situation over the last few days, or else I would have done this sooner.  Stay tuned...

EDIT - I'm adding a thought to this entry that occurred to me today.  The photo linked to by 1963maniacs may also have featured shorting by pieces of foil or metal tape on top of the light bluish gray connector, sandwiched between that and the dark bluish gray connector stacked on top of it, then leading into the normal input on the receiver.  While this is certainly a solution, although not a durable one, it would not have been implemented correctly in that photo.  Since the wire leads are facing out the wrong side of the box, this would be putting backwards polarity into the light bluish gray connector.  The foil shorting would therefore have had to be applied incorrectly also in order to flip the polarity back to normal again on the stacked dark bluish gray connector leading to the PF receiver.  Such are the pitfalls of incorrect information or trial and error.  Following the lead of this example unnecessarily confuses the issue, and so I recommend not doing it that way.

Edited March 10, 2021 by UltraViolet
Additional information.

[UltraViolet]

***Disclaimer - I should have said this before, though I think everyone should be aware - do this at your own risk!  I have thoroughly done my research to the extent possible, and have competently verified everything using a digital multimeter and the various accessories I have on hand.  These instructions are about as simple, clear and concise as I can make them.  If after reading through this you feel confused or lack the skills/tools to attempt this, either don't try it or find someone else more experienced than you to do it for you.  You will always need to make any future connections with the correct polarity, so be sure to label your components properly, and be careful!  This cable should only be used for situations I've described - don't use it for anything else because it shouldn't apply to any other configurations.  If you view any other photos or mod descriptions elsewhere on the internet, be certain to check that they are correct.  I have personally seen at least three examples of incorrect mods out there, and more than one mislabeled PF pinout diagram.

  Here is an actual illustration of the cable modification I detailed earlier.  For my photos I used a generic piece of ribbon cable, as I don't have enough PF extension cables to spare right now that I'd want to cut up fresh.  The procedure is exactly the same anyway and can be done at any point along the length of the wire:

1. Split the ribbon in the center and spread the remaining pairs.

2. Strip the wires bare in each pair.  Offsetting the strip point will avoid the need to insulate the stripped spots from each other after.  If it is easier for you to cut completely through the wire in order to strip it, then you would have the option to use heat-shrink over each pair.  In my simple example, you can just wrap the whole area with one piece of electrical tape.  (I'm trying to make this method as easy as possible for a wide range of skill levels.  If I were actually building it myself, I would probably opt for heat-shrink because it provides a more professional finish.  Cutting the wire completely through would also allow you to significantly shorten the length of the modified cable if desired.)

3. Pinch each pair of bared wires together with needle-nose pliers and bond them with solder.  (If you chose to cut completely through the wire in Step 2, you would have the option to twist the wires together, but I strongly recommend soldering for proper strength and conductivity.)

4. Wrap the area with an insulating tape.

5. Mark which face/side of the Light Bluish Gray connector end is always battery positive so that you will never forget when connecting - do not get this wrong!  If this is not enough to remind you to preferably only ever use the modified cable for this one and only purpose, additionally mark it in some other way that is obvious, like using red electrical tape or heat-shrink for the protective wrap.  (Technically you could also safely use this cable to make a PF Servo travel to and lock at 90 degrees clockwise with just the bare cable, or travel between 90 clockwise/center/90 counter-clockwise using all three positions of a PF reversing switch in your connector path/stack.)  Remember - once you modify the cable, the onus is on you to connect the studded end to the battery box the correct way every time in order to avoid damaging your accessories.

  When using the 4760 9V studded battery box as your power source, you must observe the proper polarity of your connections as follows - with the on/off switch facing you, the cable may face straight away, or alternatively towards the right side (left or towards you is reverse polarity - do not do this!).  Note again that I have clearly marked the always-positive side of this battery box with a red tile:

  You can now connect the normal power input connector on your IR receiver either at the dark bluish gray end of the modified extension cable, or stacked on top of the light bluish gray connector at the battery box end.  It doesn't matter which end because this modification routes PF battery line power to both ends of the cable.  As I mentioned earlier, I cannot speak to the safety of making the cheated connection on the IR receiver by attaching the battery power in through one of the motor driver output connectors, but I certainly would not recommend it.  This modified cable is not the same and should not be installed that way - only use the built-in input cable on the IR receiver as LEGO intended.

 

  Now I have one bonus tip for everyone.  Did you know that LEGO provided us with a very simple polarity and power-on indicator as a standard part?  The 4767 light brick turns on solid when standard positive/forward polarity is present, but also helpfully turns on flashing when reverse polarity is applied to it.  Once you figure out which orientation of the brick makes the light turn on solid, mark the side matching battery positive (red tile side) with a "+" sign or a red dot, and then you will always be able to check polarity reliably while also indicating presence of power on any studded electrical connection point.  I printed a "+" sign on adhesive label tape with a Dymo printer:

  I'm using a 4770 red cover on the bulb to highlight what it is representing.

 

  Be mindful, and you will have happy modding!  If you find anything to be in error, an omission, or simply have some additional helpful suggestions to provide, please post.

Edited March 7, 2021 by UltraViolet
Added missing word.

[1963maniac]

Thanks for all this good information, UltraViolet. Much appreciated.

Has anyone used those Znter batteries with a buggy motor vehicle or a vehicle using large tracks or any heavy vehicle?

[XG BC]

On 3/7/2021 at 12:04 AM, UltraViolet said:

  Thank-you for recounting your experiences.  While unfortunate, they at least illustrate precisely the reason why I was trying to have everyone err on the side of caution.  I see in the image linked to by 1963maniacs a V2 receiver that appears to have battery source connected in via one of the motor outputs.  I can't see properly from the angle in the photo, but let's go with this premise for the moment to explore what would happen.  If this were just a pure PF setup, that would work safely, because the PF battery lines are simply connected through internally between the receiver input and both output connectors.  In that way, the receiver doesn't know the difference, and you could get away with still using the occupied output port by stacking.

It was at this moment that i decided to screw pf and go with 9v but thats  another story in itself and i never looked back. I dont really know why lego didnt invest a few cents more and designed a reverse polarity protection circuit. I really wish you guys luck with modifying the pf receivers!

XG BC

[1963maniac]

UltraViolet, If a person wanted to make something like a 9 volt lead connected to a PF cable, how should it be wired. 

Edited May 7, 2021 by 1963maniac

[Toastie]

@1963maniac is that your cable you have or do you want to make your own?

In any case the two PF outer leads (of the four) are the +/- leads you need to connect to the 9V battery clip. On that one the larger connector is + (usually connected to a red wire), the smaller one is - (maybe with a black wire).

Here is one (of many) good tutorials how to do the PF wiring: https://scuttlebots.com/2014/03/02/lego-pf-hacking-wiring/ 

Best
Thorsten 

[1963maniac]

 

1 hour ago, Toastie said:

@1963maniac is that your cable you have or do you want to make your own?

I want to make my own. Thanks for your response.

So connecting the C2 and 9V wires to the "+" 9V battery wire, usually red wire. And then connecting the 3 remaining wires together is correct (C1, GND, and "-" 9V battery wire, usually black wire). This is correct?

Edited May 8, 2021 by 1963maniac

[Toastie]

8 hours ago, 1963maniac said:

This is correct?

Not exactly

1) For powering a PF receiver, you connect +9V of the battery to the 9V PF wire (in reference to the above link: The rightmost PF wire), - of the 9V battery to GND (the left most PF wire) and leave the C1/C2 lines open.

2) If you want to power a PF motor off an 9V battery, then you connect +9V / -9V battery terminals to C1 and C2. However, in this case make sure that the motor is spinning in the right direction. If not, reverse C1/C2. @dr_spock (and myself) is using DuPont connectors to do the C1/C2 line switch by just turning one DuPont connector around, see his post above.

3) You can connect - as @UltraViolet has shown, "battery +9V" to PF 9V and C2, and "battery -9V" to PF GND and C1. In this case though the spinning direction of a PF motor is fixed. There is no harm to either PF motor or PF receiver, as in the receiver, the power input C1/C2 lines are not connected internally; on a PF motor, the 9V and GND lines are not connected internally.

Be careful though with the power feed to a PF receiver though. That one needs "battery +9V" on the PF 9V wire, and "battery -9V" on the PF GND wire. No switching here!

What do you want to run off the battery? A PF motor or a PF receiver?

Best
Thorsten

Edited May 9, 2021 by Toastie

[1963maniac]

 

On 5/8/2021 at 9:04 PM, Toastie said:

Not exactly

1) For powering a PF receiver, you connect +9V of the battery to the 9V PF wire (in reference to the above link: The rightmost PF wire), - of the 9V battery to GND (the left most PF wire) and leave the C1/C2 lines open.

2) If you want to power a PF motor off an 9V battery, then you connect +9V / -9V battery terminals to C1 and C2. However, in this case make sure that the motor is spinning in the right direction. If not, reverse C1/C2. @dr_spock (and myself) is using DuPont connectors to do the C1/C2 line switch by just turning one DuPont connector around, see his post above.

3) You can connect - as @UltraViolet has shown, "battery +9V" to PF 9V and C2, and "battery -9V" to PF GND and C1. In this case though the spinning direction of a PF motor is fixed. There is no harm to either PF motor or PF receiver, as in the receiver, the power input C1/C2 lines are not connected internally; on a PF motor, the 9V and GND lines are not connected internally.

Be careful though with the power feed to a PF receiver though. That one needs "battery +9V" on the PF 9V wire, and "battery -9V" on the PF GND wire. No switching here!

What do you want to run off the battery? A PF motor or a PF receiver?

Best
Thorsten

Thanks very much for the clarification!!

Yesterday, I successfully made Ultraviolet's cable modification (above). Now I can use my old 9V buggy motors with an IR receiver and RC remote control. I also recently received some batteries with smart technology to stop overcharge and over discharge. Love it!!

Edited May 7, 2022 by 1963maniac
updated correct picture

[Toastie]

Very nice!

In case of "too much cable in your way" - but you don't want to hack the PF receiver cable directly - you can also make that "UltraViolet +9V/C2 and C1/GND connection" very close to the light gray PF terminal, cut the wires right there and stack the dark gray PF connector of the receiver directly onto the light gray connector on the battery box. And you have a dark gray connector to play with  (That's what I did with a good number of these PF extension cables )

(Just make sure that you don't turn around that light gray PF connector on the 9V battery box. There is some diode protection in the receiver, but that's it, as far as I remember. Others here may know better.)

Best,
Thorsten

[recklessGlitch]

Now we're talking!!! Thanks folks :)