I talked to lego S@H and learned some stuff

[Carefree_Dude]

Alright, I Tried to order some PF train parts, and learned this:

1) The PF train motor will be sold at S@H after christmas

2) The 9V battery box will be sold at S@H after christmas

3) The Rechargable battery box may come down in price around this same time

4) A train wheel pack will be coming out as well (dunno what this will include)

5) Straight track is currently cheaper to buy from the curve and straight pack track. 8 pieces of straight alone will cost 17.99

6) A straight track pack is being considered

7) Flex track may be changed

I also asked about future train sets and he said he cant say anything

Edited September 30, 2010 by Goldenmasamune

[Lego Otaku]

Unecessary quote of entire message removed by moderator - TB

Nice, especially on cheaper rechargeable battery and making other PF parts available. I wonder what change flex track are getting though... changed to "Clearance sale $1 a set" I hope. A few is OK for dealing with odd track geometry but no one really needs more than 10 no matter how big the layout gets.

[Brickthus]

Nice, especially on cheaper rechargeable battery and making other PF parts available. I wonder what change flex track are getting though... changed to "Clearance sale $1 a set" I hope. A few is OK for dealing with odd track geometry but no one really needs more than 10 no matter how big the layout gets.

Flexi-track is good if you're making a tram track through a street.

Since I did this ballasting scheme, I've updated it so that the tiles in the middle line up with the studs along the trackside. That means the central tiles can represent either sleepers (alternate black/dark bley with bley tiles) or a street surface (constant colour or cobbles). I already have a ballasting scheme for the surrounding plates outside the track.

Less change might be best, unless they're going back to the first prototype (without the check rails). That was much better looking, even if TLG's feeling was that there would be too many derailments for kids at sharp radii. AFOLs were asking for wider radii (56 studs or more), at which radii the prototype was less prone to derailments.

I'm experimenting with wide-radius flexitrack (72 or 104 studs radius) having less drag than alternating standard curves with 1 or 2 straights between each one. It looks promising, even though it's not 9V compatible.

I have also succeeded in canting flexitrack to 8 degrees, the maximum cant on British railways (track is canted but trains tilt). That means trains could go 15% faster and stay on (given a typical centre of gravity 32mm above the rails)! I'm working on sloping it as well, for hills.

I agree that a cheaper rechargeable battery box would be good. I think you can get more juice out of it than from an AAA battery box, with a 2-motor train. Both have an 800mA current limit but the rechargeable battery has lower internal resistance than AAAs and has a restart function so it will get the train up the hill after a few attempts if the power is running low, allowing you to get it to the charging point. Now I just need an inductive charging system, like the ones for phones, so I wouldn't have to plug the train into the transformer! A cheaper transformer would be good cos it's a rip off at the moment. It should be £10. AFOLs need one per battery box because the charging time is 4x the running time.

Mark

[ZueriHB]

I agree that a cheaper rechargeable battery box would be good. I think you can get more juice out of it than from an AAA battery box, with a 2-motor train. Both have an 800mA current limit but the rechargeable battery has lower internal resistance than AAAs and has a restart function so it will get the train up the hill after a few attempts if the power is running low, allowing you to get it to the charging point. Now I just need an inductive charging system, like the ones for phones, so I wouldn't have to plug the train into the transformer! A cheaper transformer would be good cos it's a rip off at the moment. It should be £10. AFOLs need one per battery box because the charging time is 4x the running time.

Mark

What kind of load do you have on your battery boxes? My charging time is about 2.5h after about 6h running time (one or two motors, PF lights).

Also there should be a topic in train tech about charging the battery box trough a 9V motor. You could also increase the voltage up to 18v for shorter charging times.

[fred67]

I agree that a cheaper rechargeable battery box would be good.

Definitely... I don't get one until I can reasonably update several of my trains without going broke.

Now I just need an inductive charging system, like the ones for phones, so I wouldn't have to plug the train into the transformer!

It would be fantastic to have a track section with a "charging mat" and just be able to park the train over it.

[MetroiD]

Very useful info - thanks, Goldenmasamune! I'm planning on purchasing a few of these battery box so obviously I'll put that on hold until the end of 2010 ;)

@ Mark: invaluable insight, as usual. I need to do some experimenting with the flex-track on my own, especially since I was considering using it for a tram street layout. I ditched that for 9V though, but I might still end up going back to the flex-track + PF option after your comment.

[CP5670]

Now I just need an inductive charging system, like the ones for phones, so I wouldn't have to plug the train into the transformer! A cheaper transformer would be good cos it's a rip off at the moment. It should be £10. AFOLs need one per battery box because the charging time is 4x the running time.

According to this thread, you don't actually need the overpriced Lego 10V transformer. A common 12V transformer will do.

[Toastie]

According to this thread, you don't actually need the overpriced Lego 10V transformer. A common 12V transformer will do.

Yes it does. I can report that a dirt-cheap "12V/6A DC supply" connected to a 9V track layout with multiple power feeds is reliably charging the LEGO LiPo on the fly - at least for 2 months now. It cranks out 13V on average and is connected to the LiPo via a bridge rectifier resulting in about 11.6 V. There will be a discussion on this issue in the next RailBricks journal/blog (regarding the long term performance of the LiPo with charging voltages exceeding the 10V TLC - hmm - "recommendation").

Regards,

Thorsten

[Lego Otaku]

Flexi-track is good if you're making a tram track through a street.

Since I did this ballasting scheme, I've updated it so that the tiles in the middle line up with the studs along the trackside. That means the central tiles can represent either sleepers (alternate black/dark bley with bley tiles) or a street surface (constant colour or cobbles). I already have a ballasting scheme for the surrounding plates outside the track.

Part of the reason I didn't like flexi is the wide gap between track section seems to make a bit more noise than train on non flexi tracks.

As other mentioned, flexi track can be used to make wide radius curve that is more in scale with rest of the train sets (especially if you go 7 or 8 wide train vs Lego standard 6)

[Brickthus]

What kind of load do you have on your battery boxes? My charging time is about 2.5h after about 6h running time (one or two motors, PF lights).

Also there should be a topic in train tech about charging the battery box trough a 9V motor. You could also increase the voltage up to 18v for shorter charging times.

I tend to load the battery box to almost its maximum 800mA output. This gives about 1/2 hour running time for an average 1 lap per minute of a 16ft x 12ft looped eight with 1 in 30 slopes and a heavy train.

I had thought about the 9V motor conversion to double socket, for track charging or hybrid trains, but I have 60 motors to convert

According to this thread, you don't actually need the overpriced Lego 10V transformer. A common 12V transformer will do.

I knew the official transformer was well overpriced but I hadn't had time to investigate other options. 10V at 700mA is the power input spec, so a rectified 12V, as suggested, should work. The current limit means I would recommend a power supply of no more than 1 Amp. I think Maplins used to do an 800mA one.

By all means have a multi-tap power supply for charging multiple batteries at once. I'd recommend individual current limits on them though.

I'm not so sure that higher voltages are such a good idea with the LiPo battery. Perhaps cell life is shorter the further above 10V we go, due to stress? I would need to look into it. How do laptop power supplies compare?

Mark

[Toastie]

I knew the official transformer was well overpriced but I hadn't had time to investigate other options. 10V at 700mA is the power input spec, so a rectified 12V, as suggested, should work. The current limit means I would recommend a power supply of no more than 1 Amp. I think Maplins used to do an 800mA one.

By all means have a multi-tap power supply for charging multiple batteries at once. I'd recommend individual current limits on them though.

I'm not so sure that higher voltages are such a good idea with the LiPo battery. Perhaps cell life is shorter the further above 10V we go, due to stress? I would need to look into it. How do laptop power supplies compare?

Mark

Mark,

you are absolutely the electronics guru here and I am just trying tings out and draw conclusions. That said: I could not get more than 600 mA charging current into the LiPo, even with an empty LiPo and a stalled XL motor on the PWM output set to full power. Did you manage to get more primary charging current flowing? My power supply delivers easily more than 5 A, but they simply do not go into the LiPo.

Secondly: The LiPo charging circuit appears to be a smart text-book LiPo charging circuit, note the inductivity, diode, and capacitor combination along with the nifty IC (numbers printed on it don’t make any sense to me though) used in typical “step-down buck converters”. These do generally accept a wide range of input voltages and handle the "dowstream" LiPo charging current (on the "other side" of the IC) very smartly - no damage possible here.

Thirdly: LEGO legals must be smart people. Now the LEGO engineers put a plain vanilla input jack into the LiPo - and dirt cheap wall warts come with matching output plugs that in addition can easily change polarity. A kid playing at home may actually figure out how to plug the plug of that wall wart into the LiPo. And now what? Boom? I don't think so. There must be several safety stages built into that LiPo. Otherwise they would have used a super-shaped fancy LEGO input jack, see the PowerFunctions terminal, don't you agree?

Maybe you have some time to take a closer look on your LiPo or Philos photos (It would be extremly helpful to know what TLC put in there; at least $25 vs. $6. And maybe more people may be willing to pay $50, once the LiPo is considered to be indeed a very fancy PF device). I would really appreciate that.

Best regards,

Thorsten

[Brickthus]

Mark,

you are absolutely the electronics guru here and I am just trying tings out and draw conclusions. That said: I could not get more than 600 mA charging current into the LiPo, even with an empty LiPo and a stalled XL motor on the PWM output set to full power. Did you manage to get more primary charging current flowing? My power supply delivers easily more than 5 A, but they simply do not go into the LiPo.

Secondly: The LiPo charging circuit appears to be a smart text-book LiPo charging circuit, note the inductivity, diode, and capacitor combination along with the nifty IC (numbers printed on it don’t make any sense to me though) used in typical “step-down buck converters”. These do generally accept a wide range of input voltages and handle the "dowstream" LiPo charging current (on the "other side" of the IC) very smartly - no damage possible here.

Thirdly: LEGO legals must be smart people. Now the LEGO engineers put a plain vanilla input jack into the LiPo - and dirt cheap wall warts come with matching output plugs that in addition can easily change polarity. A kid playing at home may actually figure out how to plug the plug of that wall wart into the LiPo. And now what? Boom? I don't think so. There must be several safety stages built into that LiPo. Otherwise they would have used a super-shaped fancy LEGO input jack, see the PowerFunctions terminal, don't you agree?

Maybe you have some time to take a closer look on your LiPo or Philos photos (It would be extremly helpful to know what TLC put in there; at least $25 vs. $6. And maybe more people may be willing to pay $50, once the LiPo is considered to be indeed a very fancy PF device). I would really appreciate that.

Best regards,

Thorsten

I agree about the safety margins. I would like to determine how close the design intent is to them, to optimise the solution.

I have a candidate for the charger chip, so I'll look into is a bit more and see what to recommend. I don't think it would charge any faster by upping the voltage, so maybe rectified +/-12V, giving 10.6V, is a good start. I'm reluctant to open up a battery, since these days I like to be able to put things back together properly afterwards! I'll see how far I get with Philo's photos.

Logically in the PF product line design, the power supply would not be the weak link, so its 700mA rating is just above the 550-600mA used. That makes sense since it's no bigger (and more expensive in components) than it needs to be for manufacture.

Mark

[Toastie]

I'm reluctant to open up a battery, since these days I like to be able to put things back together properly afterwards! I'll see how far I get with Philo's photos.

It is fairly easy to open the LiPo up. There are four plastic "plugs" hiding the 4 screws. I used a small sharp drill bit, turned it 2 times into the plastic plug and pulled it out. Then just loosen the srews and the top part with all the electronis and the battery comes off. There is hardly any damage you can do and can be put back togther rather nicely. I did it twice, because I thought Ihad killed the LiPo electonics when going above 20V.

Regards,

Thorsten

[Brickthus]

There is hardly any damage you can do and can be put back togther rather nicely. I did it twice, because I thought Ihad killed the LiPo electonics when going above 20V.

Regards,

Thorsten

I looked at the data sheet for a Texas Instruments bq24103 LiPo charger chip (hence the TI and BQ markings, the CK identifies the 24103 from the series). The circuit is fairly standard, though the status LEDs are driven by the Alpha chip rather than by the LiPo chip outputs. The output inductance is substantial, being 220mH rather than the smaller inductances in most of the data sheet circuits. The current sense resistor is larger than standard (0.22 ohms rather than 0.1 ohm).

The components in front of the chip supply input are the D11 diode, L2 inductor and a few capacitors, so there's no SMPS in front of the chip, just a single diode drop. A buck converter would have required a switching component for oscillation and there is no evidence of one. I think L2 and the capacitors are just a Pi-network to minimise noise and ripple.

The chip's absolute maximum voltage input is 20V, so no wonder it played dead!

The chip's recommended maximum voltage input, including all inherent switching noise spikes, is 16V. Therefore, if you insist on exceeding the standard 10V, I recommend 12V as the highest standard voltage level (multiple of 1.5V up to 9V, or 3V thereafter) to be used from an alternative power source, so that spikes are less likely to exceed 16V. An alternative power source should be capable of supplying 700mA but not more than 1 Amp per battery. Check also the level of regulation required on the power source because both regulated and unregulated wall warts are available. I guess the maximum voltage could be 1.414 (root 2) times the nominal voltage for an unregulated source. 14.14V is less than 16V but 16.97V is more than 16V. Therefore only go up to 12V with a regulated source. I could try it from my bench power supply, which I use for powering 9V main lines anyway (more current than a standard controller).

Given that the chip includes its own FETs for switching, you might also like to try a 9V source, which would not hurt anything. See if the charging rate is any slower than with the standard 10V. The minimum voltage is 4.35V so you could try 6V too.

You might find that a 13.8V power supply is tweakable via an internal potentiometer. Always have the lid on when it's powered (live mains), but turn off, allow to discharge capacitors and then tweak it. I used my 3A one to charge my car battery through 4m of 3A mains cable (resistance 0.3 ohms) once I had tweaked it up to 14.75V no load voltage. It picks up well where a standard charger gives up, for longer slow charging.

Sorted without taking the lid off!

Mark

[Buddha Bricks]

I hope i'm no too off topic here. Wondering if someone tried changing the pack with a "rc and/or airgun" lipo charger.

The one i have has multiple option for charging nimh/nicd/lipo/life batteries, and also will let me chose the amps output.

I think this may be a nice alternative.

Another thing, I allways make sure to balance the lipos i use for RCing so that both cells are at 3.7v (well technicly 4.2v) as i've been told this helps preserve the battery life, but i don't think that the lego charger has that option... right?

To do so it would need a wire going to both cells and a microchip for controling the balance. Any feedback anyone?

[Toastie]

I hope i'm no too off topic here. Wondering if someone tried changing the pack with a "rc and/or airgun" lipo charger.

The one i have has multiple option for charging nimh/nicd/lipo/life batteries, and also will let me chose the amps output.

I think this may be a nice alternative.

Another thing, I allways make sure to balance the lipos i use for RCing so that both cells are at 3.7v (well technicly 4.2v) as i've been told this helps preserve the battery life, but i don't think that the lego charger has that option... right?

To do so it would need a wire going to both cells and a microchip for controling the balance. Any feedback anyone?

Hi Buddha Bricks,

well, I guess the thing is that the LEGO LiPo already hosts a fully blown charger circuit with all bells and whistles. You don't need any sophisticated electronics to make the LEGO LiPo happy. It has everything on board. All it needs is some DC in; it appears as if 12 V from a plain vanilla wall wart is a good choice.

Regards,

Thorsten

[Brickthus]

I hope i'm no too off topic here. Wondering if someone tried changing the pack with a "rc and/or airgun" lipo charger.

The one i have has multiple option for charging nimh/nicd/lipo/life batteries, and also will let me chose the amps output.

I think this may be a nice alternative.

Another thing, I allways make sure to balance the lipos i use for RCing so that both cells are at 3.7v (well technicly 4.2v) as i've been told this helps preserve the battery life, but i don't think that the lego charger has that option... right?

To do so it would need a wire going to both cells and a microchip for controling the balance. Any feedback anyone?

Given that I run the LiPo battery to its maximum output of 800mA, one option for more powerful trains is to make a larger battery, perhaps 2S2P, with a 2 Amp output current. This would need cell balancing, more so than the 2S1P battery we have because the cells are in parallel. However, the current capacity of PF leads is unlikely to be much more than the 800mA output of the existing battery, since all elements of the system have been designed to work together. This one would have the same capacity as a set of alkaline AAs at one third of the weight, but the current capability is very high, requiring a circuit to keep it safe, as well as a standard non-LEGO charger to sort out charging and balancing.

Therefore a more suitable way to get more power would be to use slave H-bridges. An IR receiver output should go to a number of H-bridge inputs, one per pair of PF train motors, each pair being supplied from a different battery source. That way, all locos in a train get the same control signals, with no chance of a speed signal going to one loco and not the others (causing derailment). Unfortunately it means more batteries, so hopefully the price will drop. I see the 2100mAh 2S3P one is just $14.99, though I expect the charger circuit and speed control circuit in the LEGO battery cost more to make. I would have thought a price of $25 would be possible though. $30 with the recent 20% price hike

The way the IR receiver H-bridge chips are rated, using one per motor could allow more power if the battery has the capability. Just need to make sure that things are not run outside their ratings, including using a heatsink where necessary. The chips can be used with both sets of H-bridges paralleled up, though this is not possible whist they are inside the receiver, unless the correct IR codes are sent to keep red and blue outputs at the same speed as each other all the time i.e. NXT and IR Link sensor control.

It would be useful to sort out a PWM reduction circuit to equalise speeds between train motors and the Emerald Night loco. This would need some sort of table in a chip, to set the right PWM at each speed setting. The diodes I'm using at the moment work up to a point, but they limit the power to the train motors when they need all the power they can get in order to pull the heavy train up hills and round corners. Maybe a system based on the bar code truck set 8479 would work, whereby the speed sensor wheel would be attached to an unpowered wheel of the train and the programming of the bar code unit would cause more power to be sent to the loco motor in proportion to the input frequency.

Maybe replacing the current limit device would be an option, for those prepared to void the warranty and take the risk. The LiPo cells are easily capable of faster discharge. I would consider a 1 Amp device rather than the 800mA one, but it's just the speed and regulator circuit ratings that might be exceeded. The risk of cooking anything is up to you! I recommend you get a CO2 fire extinguisher if you want to try this sort of thing, so you don't burn anything but the battery! Make the train roof easily removable, so you can get the CO2 in if required. A slave H-bridge of higher rating might be a better way to go (1 per motor), so all the power components are non-LEGO and receive the command from the IR receiver.

Mark