Giottist

Rechargeable batteries for powered up hubs

Recommended Posts

 

Hi LEGO train folks,

I've found a preliminary soution for replacing environment polluting AAA cells with a Li-Ion rechargable batterie. Using one way AAA cells is not a pleasant game since you spend a lot of money and produce a heap of problematic waste just to run your train for a couple of hours. What's about rechargeable batteries?

45908757304_afea849d93_z.jpg

Original hub with six expendable AAA cells

Yes, there are two solutions. First is to replace the AAA cells with Li-Ion cells of the same form factor, and yes, they exist. I've found a supplier on ebay who sold me the cells for little money.

45718732245_39afb4869b_z.jpg

Two needed cells and how they are put into the battery holder

These AAA Li-Ion cells have the same form factor than common AAA batteries but nearly triple voltage. You must not put six cells into the holder, otherwise you destroy the hub immediately. Just put two cells in it and solder a small wire between the firs and the last contact in the holder.

46580870802_888ec00f8f_z.jpg

The VCC contact for the first cell is connected to the GND connector of the last cell by a soldered wire. It is easy to solder it and needs so little time that the holder plastic has no opportunity to melt. Some experience with soldering is a good idea ;)

I've tested it with my train motor and the lights: It runs for just an hour, recharging told me the capacity is abot 200 mAh and not the 350 mAh printed on the cells. Do not believe whats printed on the batteries, this is pure marketing. Hmm, not the best result but no surprise since the hub is filled mostly with air instead with battery cells.

There is a much better solution. There are Li-Ion batteries with the form factor of a common 9V block available. I've found them on ebay too. Look for "6F22", "9V block" and "Li-Ion". Average price is abot 6 € if you buy one, 5 € if you buy two or four and down to 4 € if you buy 10 batteries. The nominal capacity is 650 mAh but this is overoptimistic, real capacity ist abot 460 mAh measured by my own. Not bad at all.

46580871182_41be7d00ba_z.jpg

The big advantage is it fits nealy perfect into the train hub. Filling the hub with batteries instead of air is promising. Another advantage of the form factor is the connector clip which avoids fatal polarity errors! The 9V block form needs only an adapter to the hub contacts to make the whole nearly fool proof. I've found here on Eurobricks other "solutions" with an adapter made of cardboard and some selfadhesive copper band. This is the best way to destroy the hub by wrong polarity. Using a common connector for 9V block batteries avoid this.

46580870972_19a799b166_z.jpg The common connecto clip for 9V blocks

45718732395_e2ed9215f9_z.jpg The other side ... Please look for the postion of the contact strips

45718732805_ec75ba8911_z.jpg ... and the mounted adapter ..

The adapter it self is very simple and consists just of a matching piece from an expired "what-so-ever"-card (in this case an expired bank card, which has to be destroyed to prevent misuse) On one side two strips of self adhesive copper band are put on the plastic sheet just at the positions for good contact with the leads of the LEGO hub (see the middle image above). The clip is soldered in this way that it find its final position on the other side of the plastic sheet. The red wire connects to VCC (the contact in the center of the hub), the black to GND. Soldering is easy and quick since the copper strips have nearly no heat capacity. Some soldering experience is still usefull.

Several extensive tests are very promising: I've run repeatedly a train motor idling together with the lights for 3 hours 45 minutes without a break. Recharging told me the capacity of theese Li-Ion blocks is about 460 mAh and the average Voltage is 7.4 V as expected for two cells in the block. The measured values let expect at least two hours of operation with a mechanical load, not less than expendable AAA cells. Not bad, isn't it?

The measured capacity of the 9V blocks do not match to the run time in comparison to the AAA Li-Ion cells, but I do not trust the AAA cells. 3h45' could be peproduced several times and this is the only important value.

Next step will be a 3D printed form piece to replace the cutted card. This 3D adapter should contain the connector for the 9V block, the metal strips to connectz the hub and a notch to fit into the hub to prevent exchanging the polarity. Who is able to design this device? I'm sure there is a large demand ...

Hope I can help you with this solution ... There is potential.

 

Share this post


Link to post
Share on other sites

Hi,

a nice and interesting solution!

How does the charger unit look like?

You should seek for help with the guys of 4Dbrix.

They have a lot of experience in 3D-printing and electronics.

 

Regards from Hamburg

 

CaL

Share this post


Link to post
Share on other sites
15 minutes ago, CaL said:

You should seek for help with the guys of 4Dbrix.

They have a lot of experience in 3D-printing and electronics.

I think at the people from TrixBrix ... I hope both read this discussion.

Share this post


Link to post
Share on other sites
Posted (edited)

I'm using Panasonic Eneloop Pro rechargeable batteries. They have 950 mAh.

With your LiIon solution, you end up with only 350 mAh or 650 mAh. 

I think it makes no sense to modify the battery holder unless you get significantly more than 1000 mAh.

 

51a13b9FduL._AC_US436_FMwebp_QL65_.jpg

 

 

Edited by legotownlinz

Share this post


Link to post
Share on other sites

Pardon my ignorance, but why not use normal AAA rechargeables? I have about 60 Eneloop's I use with my Boost, Powered UP and WeDo 2.0 hubs with no issues.

Share this post


Link to post
Share on other sites

Wouldn't the 9V Li-Ion make battery box shorter in height which might be useful like in a slug engine MOC? 

 

Share this post


Link to post
Share on other sites
8 hours ago, legotownlinz said:

I'm using Panasonic Eneloop Pro rechargeable batteries. They have 950 mAh.

With your LiIon solution, you end up with only 350 mAh or 650 mAh.

Please do not believe what's printed on the cell. This has nothing to do with reality. I'm using a charger with a lot of rather precise measurements i.e. the real capacity. I've found the AAA Li-Ion cells has less than 200 mAh in reality than 350 mAh printed on. I have severe doubts that your 950 mAh are real. The half at maximum is more realistic.

More important is the fact that NiMH cells are difficult to charge. I have tried a couple of chargers (to be honest more than five ...), but each destroyed the cells after 3 to 5 cycles by overcharging because charge end detection is very difficult and not solved by most chargers. Perhaps you are the lucky owner of a working one. Can you tell us which kind of charger you use? I for myself banned all NiMh stuff: 

My Li-Ion solution offers 460 to 480 REAL mAh (measured and confirmed multiple, the 650 mAh printed on the battery is pure marketing) and runs a train with realistic load for more than two hours. And charging is reliable, the life span will be hundreds of cycles.

How long your trains runs with full batteries?

 

 

 

Share this post


Link to post
Share on other sites

Eneloops are some of the best batteries and I’ve never had an issue charging them with the Panasonic smart charger they ship with.  It shuts down when fully charged and does each cell individually.  The mah is close to what they claim

Share this post


Link to post
Share on other sites

Thank you all for the hint with original eneloop cells in combination with an original panasonic charger. It's worth to test them. May I ask anybody to let a train motor idling together with the lights from full charge to an orange blinking hub and tell us the time? Otherwise I spent another 30,- € to test them. I'm curious now. I can faint remember I've use eneloop batteries in the distant past but no original panasonic charger ... Hmm.

BTW, at the moment I'm very content with my Li-Ion solution.

Share this post


Link to post
Share on other sites

Is it possible to open the top part of the hub to take out the pcb easily? Bare 6f22 battery should fit in 2 studs width, and I wonder what's the size of pcb itself. Could make those smaller engines possible finally:)

Share this post


Link to post
Share on other sites

Ouh, better not. I have no plans to modify the original hardware, so I did not try or even thought about it. The only exception was the experiment with the two AAA Li-Ion cells which I count as a flop. I can remember a pcb image in the tear down thread on the first page. It seems quite larger than a 9V block.

Share this post


Link to post
Share on other sites

I've never had any problems charging NiMH batteries. NiMH batteries are easy to load compared to LiIon.

I'm not using a Panasonic charger but a charger from ELV that is at least 10 years old. 

Share this post


Link to post
Share on other sites

I have to back that up - I've used both Eneloop and GP ReCyko Pro rechargeable AAA's and AA's over the years with no issues. I use both a GP ReCyko charger and a cheap 16 bay one I got from Amazon.

I get a few hours (maybe 3ish?) from my Powered UP trains per charge and then I charge them again. Quite convenient.

I have no idea about their mAh properties, I've never cared - they just work. :) I pop six of them in a hub like any other battery and off I go.

Share this post


Link to post
Share on other sites

Well, all this can be summed up rather easily:

It is all about the Ah - current A delivered by the battery over time t measured in hours h. This is sort of the equivalent of power density, as the discharge process (running the motor) converts chemical energy stored in the battery into mechanical work. Let us just consider the first law of Thermodynamics and convert the chemical energy stored in the battery and expressed as Ah entirely into mechanical work (which cannot be, as we do not take into account entropy changes*huh*). I know: Smart as* … 

Ah is what we have. The ever reached max value is printed on the (rechargeable) battery. This may be far off from reality, as battery manufacturing companies want to sell their stuff - but let us assume Eneloop is a reliable company not telling stories but true Ah values. As the LiPo folks do, Giottist is referring to.

The more Ah you have, the longer a "defined standard train" will run. We need to define "standard" though. @Giottist was using a standard procedure he defined: motor with nothing to pull (he calls idling) and in addition operation of an LED light. However, even that standard may suffer from "what LED light" and "what type of motor".

All that really matters is the current that is flowing through the system. And that is not readily measured (one would need to splice cables and measure current in A). Time as measure is "fairly remotely" OK - but time does not account for any variations in the setup (friction, make, model, etc.). Idling is a reasonable standardization, I believe. I also believe that when it comes to a real train pulling some load, that the picture changes significantly, as the drawn current goes seriously up -> see Philos pages dealing with that in every detail.

Lastly and most importantly, there is a spatial limit of storing chemical energy. LiPos and LiIons are today the best in that regard. However, 6 AAA NiMH simply do outperform any "9V LiPo" Ah wise as they simply have more room. Would the 6 AAAs be of the same size as an equivalent LiPo, the LiPo would win easily.

But: This is not the case here.

Hope that helps.

All the best
Thorsten

 

 

       

   

Share this post


Link to post
Share on other sites
8 minutes ago, Toastie said:

Well, all this can be summed up rather easily:

It is all about the Ah - current A delivered by the battery over time t measured in hours h. This is sort of the equivalent of power density, as the discharge process (running the motor) converts chemical energy stored in the battery into mechanical work. Let us just consider the first law of Thermodynamics and convert the chemical energy stored in the battery and expressed as Ah entirely into mechanical work (which cannot be, as we do not take into account entropy changes*huh*). I know: Smart as* … 

Ah is what we have. The ever reached max value is printed on the (rechargeable) battery. This may be far off from reality, as battery manufacturing companies want to sell their stuff - but let us assume Eneloop is a reliable company not telling stories but true Ah values. As the LiPo folks do, Giottist is referring to.

The more Ah you have, the longer a "defined standard train" will run. We need to define "standard" though. @Giottist was using a standard procedure he defined: motor with nothing to pull (he calls idling) and in addition operation of an LED light. However, even that standard may suffer from "what LED light" and "what type of motor".

All that really matters is the current that is flowing through the system. And that is not readily measured (one would need to splice cables and measure current in A). Time as measure is "fairly remotely" OK - but time does not account for any variations in the setup (friction, make, model, etc.). Idling is a reasonable standardization, I believe. I also believe that when it comes to a real train pulling some load, that the picture changes significantly, as the drawn current goes seriously up -> see Philos pages dealing with that in every detail.

Lastly and most importantly, there is a spatial limit of storing chemical energy. LiPos and LiIons are today the best in that regard. However, 6 AAA NiMH simply do outperform any "9V LiPo" Ah wise as they simply have more room. Would the 6 AAAs be of the same size as an equivalent LiPo, the LiPo would win easily.

But: This is not the case here.

Hope that helps.

All the best
Thorsten

 

 

       

   

Right, all that may be true, but the thread title is "Rechargeable batteries for powered up hubs". I think it's important to point out that one can use standard rechargeable batteries without needing to modify your battery box or risk blowing your battery box by using too many LiPo's. NiMH rechargeable's are commonplace and provide a perfectly reasonable almost-as-good solution without risk.

However if you do want to use LiPo's, @Giottist's research and solution is awesome! :)

Share this post


Link to post
Share on other sites

 

On 1/7/2019 at 3:39 PM, Bartosz said:

Is it possible to open the top part of the hub to take out the pcb easily? Bare 6f22 battery should fit in 2 studs width, and I wonder what's the size of pcb itself. Could make those smaller engines possible finally:)

The top part of the HUB is held on by four T6 screws.  You can desolder the two metal bars on the PCB that are the connection point to the battery holder if you don't want to use them. 

Share this post


Link to post
Share on other sites
Posted (edited)

Thank you all for the discussion. It helps to find out the properties of different solutions for rechargeable batteries.

@toastie: I did not plan to make real science out of this question but have an overlook since I have not the best experiences with (noname ?) NiMH stuff. I'm using the PUP train motor 88011 as the motor idling in bottom up position and the lights 88005. I know it's rather difficult to measure the average current, voltage and power for a PWM device. For a first crude look I've chosen this simple setup. At the moment I'm very busy by profession and have no opportunity to get original Panasonic Eneloop stuff, but you make me curious. It's a nice idea to make a comparison.

 

Edited by Giottist

Share this post


Link to post
Share on other sites
20 hours ago, Mr Hobbles said:

Right, all that may be true, but the thread title is "Rechargeable batteries for powered up hubs". I think it's important to point out that one can use standard rechargeable batteries without needing to modify your battery box or risk blowing your battery box by using too many LiPo's. NiMH rechargeable's are commonplace and provide a perfectly reasonable almost-as-good solution without risk.

Merde - my last conclusion was apparently way too fuzzy, I guess (Ha! and the automatic bad word removal thingy on this forum does not speak French:tongue:):

Your take is exactly what I wanted to say:

20 hours ago, Toastie said:

However, 6 AAA NiMH simply do outperform any "9V LiPo" Ah wise as they simply have more room

 So you are absolutely right: With good AAA NiMHs and much more importantly a >good< cell recharger (one that first looks at the charge state and cell condition and then decides what to) you will outperform the "9V" LiPo and you don't have to damage any hardware. 

Almost all of my trains run on NiMH cells. And almost all of them are trickle charged from the track (my train pick-up power from 9V track, which is permanently delivering 15 V DC). Even with this very nasty but easy way of recharging, I did not change any cells nor removed them from the trains for more than 3 years now.

So: NiMH is a very solid and good solution.

All the best
Thorsten   

Share this post


Link to post
Share on other sites
Just now, Toastie said:

Almost all of my trains run on NiMH cells. And almost all of them are trickle charged from the track (my train pick-up power from 9V track, which is permanently delivering 15 V DC). Even with this very nasty but easy way of recharging, I did not change any cells nor removed them from the trains for more than 3 years now.

I am very intrigued with this! Can you describe the mechanism/parts a bit more? Do you use Lego 9v track? How do you connect the wheels to the battery box (PF I presume)?

Share this post


Link to post
Share on other sites

Can do - thought I posted it here already.

Will take a few days - work is asking for too much time for the next two days.

Or maybe this helps: Power is picked up by modified 9V train motor from the permanently powered 9V track layout. Track voltage is 15V from a cheap laptop replacement power supply (these deliver relatively clean and defined DC voltage). From the motor pickup the wires go to a bridge rectifier and then to a 9V regulator (of 7809 type). From there 2 Diodes in series a) reduce the voltage going to the NiMHs cells by about 1.2 V = 7.8 V. These are connected to the series of NiMH cells (nominal 6 x 1.2 = 7.2 V, but when fully charged they have more than that). When the train runs on 9V track, power comes from the track. When the motor runs on 9V powered track, power comes from the track, when polarity changes due to wyes etc. the bridge rectifier takes care of that and when in runs in unpowered PF track (wye-insulation or flexible tack etc.) power comes from the NiMH cells.

You could also run this setup on PF track with just a couple of 9V track segments for recharging. The trickle thing comes from the small difference of cell vs charging voltage and thus small charging current. NiMH cells are pretty tolerant to that treatment.

As I said, good now for years. It may be not the most elegant and most friendly way for the cells, but it works for me (and the cells so far:classic:).

Best
Thorsten 

Share this post


Link to post
Share on other sites
Posted (edited)

Unless most other batteries, the Eneloop label specified the MINIMUM capacity, which is 930 mAh. So the actual capacity of a new Eneloop batterie should be well above 1000 mAh.

Obviously, you can't completely discharge the batteries. On the one hand, they might get damaged if fully discharged, on the other hand, the train's speed would be too low or it wouldn't move at all. However, NiMH batteries can be used until the speed decreased significantly while the Lego LiIon battery turns off automatically before the train gets noticeable slower, thus you can't use all of its capacity.

Edited by legotownlinz

Share this post


Link to post
Share on other sites
1 hour ago, Toastie said:

Can do - thought I posted it here already.

...snip...

Best
Thorsten 

Thanks for the run down! Seems like a very cool system. :)

Share this post


Link to post
Share on other sites

This morning I started the attempt to get a set panasonic eneloop AAA cells and a matching charger to reproduce the experiences of toastie and others. I has no sucess, the only offers I found were doubtful noname chargers and cells with pantasie brands - the same stuff I've destroyed multiple times in the past. I have no motivation to burn more money.

Then I looked up original cells with original chargers in different online stores - an expensive pleasure. For the same money for one set for a LEGO hub I can buy another 10 (!) Li-Ion blocks. Ok, without charger, but I have a reliable Li-Ion charger. So please understand me that I cancel my test plans for NiMH solution for economic reasons  and continue to recommend the usage of 9V block Li-Ion batteries if a suitable adpater is available.

The advantage are: Li-Ion technology is reliable, reproducable, offers sufficient capacity and run time, there is no risk to buy a wrong combination of charger and cells and the cells are by far more economic. I for myself am satisfied with a real train runtime between 2 and 3 hours.

The disadvantage is at the moment that not ready made adpter is available. Now I like to look around somebody with a 3D printer to manufacture a prototype for a foolproof adapter.

On the other hand: If you are lucky to have a running and reliable NiMH combination of charger and cells, please use and enjoy it. There is no need to change anything. Using NiMH AAAcells is more expensive but needs no modification. That's true.

 

8 hours later: Addenum:

I've found a very detailed website about NiMH cells in german language. I try to translate the most important statements into english. (Please forgive me my bad language :innocent2:)

Now it is explainable why Toastie and others have good experiences with NiMH cells and others including me not.

1) To have a reliable and functional power source you have to use NiMH cells with low self draining technology. The website mentions eneloop and ReCyco+. The manufacturers are Panasonic (Sanyo) and GP.

2) Please let any noname cell at the store. Ordinary NiMH cells have a self discharging rate up to 50% a month (!) and have to be recharged very often, best every week. If you do not so the risk of deep discharging is high.

3) Deep discharging below 0.85 V will destroy the common NiMH cell very fast. Low self discharging cells are less sensitive  but still a little endagered. It is neccessary to use NiMH cells often. This is the best for them. Playing only in long intervals will destroy even low dicharging NiMH cells

4) The website recommends to use a dedicated charger with control for each individual cell, since the parameter variation for NiMH cells is rather high. This sounds somewhat expensive.

Many thanks to Chr. Caspari from www.elektronikinfo.de

 

Edited by Giottist

Share this post


Link to post
Share on other sites

@Giottist Hey there and greetings from Austria! I have bought my eneloops from Amazon, delivered through Akku-Onlinehandel but I suspect there are lots of other reliable suppliers on Amazon or elsewhere where you can get your eneloops in Germany. The charger I use is a Technoline BC700, bought at the same source (also delivers to Germany without any problems).  It might not be the best one, but it's able to Discharge and Refresh the batteries too, so it's quite OK technology-wise. Price is around 25 to 30 €, depending where you order it.

I can just chime in and repeat the good experiences made by other users. To me, Eneloops are the way to go.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.