LEGO Train 12 Volts

Single lithium batteries for Power Function trains

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I'm doing something similar but on the basis of a 4xAA 4.8V NiMH pack. They are hassle-free as opposed to Li-ion and don't suffer the risks of premature death when over-discharging and explosion/incineration when charging.

If you deploy lithium-technology batteries please, please make sure you do so with an (integrated or added) battery protection circuit. And never, ever, charge them unsupervised / during absence.

My first experiment involved an old '70s 4.5V train, so a voltage converter wasn't needed here. But with a converter, the possibilities are endless; you can make 9V (or 12V) from a two-AA set of 2.4V if space is a concern.

I cannot recommend using a DC-DC voltage converter enough. It's simply brilliant.

Legotux

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1 hour ago, legotux said:

If you deploy lithium-technology batteries please, please make sure you do so with an (integrated or added) battery protection circuit. And never, ever, charge them unsupervised / during absence.

Yes, I absolutely agree, you don't want to burn down you precious train or even more. Also this is an interesting article that takes a different approach (link)

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2 hours ago, legotux said:

And never, ever, charge them unsupervised / during absence.

We should not overdo it, though. Time = technology is progressing as well. And: There are so many devices now running on LiPo technology, you don't even have the chance to not charge them while absent!

True, you definitely need all that electronic protection when operating LiPos. However, it costs you next to nothing, as these circuits are used all over the place. Furthermore, a tank full of gasoline "left unprotected", can blow up much more than a bunch of LiPos. Same holds true for many, many more things in everyday life!

41 minutes ago, Wabbajack said:

Also this is an interesting article that takes a different approach (link)

Spoiler

 

(Cited from that linked article) "I have always found lithium batteries to be…. amusing. They’re extremely volatile; if overcharged, they explode. If over-discharged, they explode. If charged too quickly, they explode. If discharged too quickly, they explode. If punctured, they explode. If they get too hot, they explode. If they get too cold, they simply don’t work."  = Chemistry@work :pir-huzzah2: I am asking myself, whether there is a way to let them explode, when they get too cold. There must be ... :pir-skel:

Now, LiPos are present in virtually >all< cell phones on this world: (Cited from bankmycell.com:) "According to GSMA real-time intelligence data, today, there are 5.27 Billion people that have a mobile device in the world." 

Assuming a drop-out rate of 0.001% for the safety electronics built into mobile devices, then potentially 57000 explosive devices are out there ... so far, I believe we are doing good though :pir-laugh:

 

Yes, but more or less only for "bridging gaps" in electrified sections of your layout: Cited from that article "So if we have an equal volume of supercaps to AA batteries, our run length will be 1/100th: an AA battery set lasts several hours, call it 2h on the conservative side. That means an equally sized supercap bank will run for 1.2 minutes, plenty of time for zipping through a short unpowered track section!"

In summary: (9V) powered track is the way to go!!!

Just trying to be a little funny here, don't take it too seriously. :pir-laugh:

All the best
Thorsten

Edited by Toastie

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Oh yes, I would love to just have PFX track with DCC trains, but I only have 4 PU hubs with motors, so I am always thinking about sunken cost.

Martin

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My drone instructions say to inspect or replace the lithium battery after a crash impact.  I had one battery puffed up like a bird looking for a mate.  No earth shattering kaboom though.  Maybe not the best battery type to use if you like making train crash videos.  :pir-grin:

 

 

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25 minutes ago, dr_spock said:

No earth shattering kaboom though.

Yeah, LiPos are usually "lame" in this regard; the shell around the pouch cells (this is what you were using in the drone, wasn't it?) is simply not building up enough internal pressure for the boom thing - and the chemical reaction is not fast enough to compensate for that (i.e. detonate). It more or less relaxes thermally :pir-skel:.

Fun fact: We did a master thesis recently in collaboration with the Department of Chemical Safety and Fire Defense at our university, where we deliberately (and with all possible safety measures) were blowing up different types of rechargeable batteries, including some for military applications. Believe me, with regard to the boom thing there are much better choices than LiPos. However, LiPos can of course do damage, particularly because they can develop, depending on size (capacity) and cell layout, an enormous amount of heat. Well - which is energy. When the energy density of a chemical system is as high as in a fully charged LiPo, then the potential of releasing that energy not into electrical current but heat (which for thermodynamics is more or less the same, as all is good: 1st Law of TD: check, 2nd Law of TD: check, 3rd law not relevant here) is perfectly OK. Boom wise, thermodynamics needs to kiss kinetics, and then it depends: Either your train runs for a really impressive amount of time, or - well - it "blows up" - usually in the puff-up reaction you saw ...

However: A LiPo treated nicely is as safe as a cigarette lighter filled with propane/butane treated nicely. And a really big LiPo is as safe as the cylinder for a gas grill. 

Best
Thorsten         

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4 hours ago, Toastie said:

Cited from that linked article) "I have always found lithium batteries to be…. amusing. They’re extremely volatile; if overcharged, they explode. If over-discharged, they explode. If charged too quickly, they explode. If discharged too quickly, they explode. If punctured, they explode. If they get too hot, they explode. If they get too cold, they simply don’t work."  = Chemistry@work :pir-huzzah2: I am asking myself, whether there is a way to let them explode, when they get too cold. There must be ... :pir-skel:

Now, LiPos are present in virtually >all< cell phones on this world: (Cited from bankmycell.com:) "According to GSMA real-time intelligence data, today, there are 5.27 Billion people that have a mobile device in the world." 

Assuming a drop-out rate of 0.001% for the safety electronics built into mobile devices, then potentially 57000 explosive devices are out there ... so far, I believe we are doing good though :pir-laugh:

These literary passages are too funny! :laugh:

3 hours ago, Toastie said:

 Believe me, with regard to the boom thing there are much better choices than LiPos.

The cylinder for a gas grill I can guess! :grin:

3 hours ago, Toastie said:

When the energy density of a chemical system is as high as in a fully charged LiPo, then the potential of releasing that energy not into electrical current but heat (which for thermodynamics is more or less the same, as all is good: 1st Law of TD: check, 2nd Law of TD: check, 3rd law not relevant here) is perfectly OK.

Beautiful theoretical concept and clear exposition :pir-huzzah2:  :thumbup::thumbup:

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4 hours ago, Toastie said:

We should not overdo it, though. Time = technology is progressing as well. And: There are so many devices now running on LiPo technology, you don't even have the chance to not charge them while absent!

That is true, but you can't equate an Apple iPad or an HP laptop to a battery pack you purchased on ebay or aliexpress. The big brands have reputations to worry about, and they do recalls. Chinese hoverboards are notorious, and many houses have burnt down as a direct result.

So while your LiPo won't explode in your face when you look at it wrong, taking some precautions is still wise.

4 hours ago, Toastie said:

True, you definitely need all that electronic protection when operating LiPos. However, it costs you next to nothing, as these circuits are used all over the place. Furthermore, a tank full of gasoline "left unprotected", can blow up much more than a bunch of LiPos. Same holds true for many, many more things in everyday life!

In my country, the fire department has started educating users about safe handling and charging of especially the larger lipos, like in hoverboards, steps, ebikes, scooters etc.

And I would point out that NiMH has a lower energy density than Lithium, but they won't explode, not even when you try hard to make them explode. So it's not such a bad choice to use NiMH when you can deploy either type.

 

3 hours ago, Toastie said:

However: A LiPo treated nicely is as safe as a cigarette lighter filled with propane/butane treated nicely. And a really big LiPo is as safe as the cylinder for a gas grill. 

There is some truth to that, but there are some aspects worth noting: First off, we are not yet very familiar with such chemical battery fires. For centuries, fire fighters fought gasoline fires, and they know exactly what to do in such an event. But when it comes to lithium batteries we're still very much in the learning process. These fires are very hard to put out, if not impossible, and fire fighters often let Tesla's, E-scooters etc burn out (it must be said: also for fear of electrocution).

In addition, some batteries suffered from manufacturing defects (remember the Samsung Galaxy Note 7, anyone?) and such catastrophes don't happen anymore with gas cylinders and petrol containers, because (see above) we've learned from previous mistakes during all the centuries we dealt with petrol. But 60 years ago, some car brands tended to explode when rear-ended, because the gas tank was placed unsafely. All these safety lessons we learn from accidents, we're still learning them with high-power batteries... 

3 hours ago, Toastie said:

Best
Thorsten         

Cheers

Legotux

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5 minutes ago, LEGO Train 12 Volts said:

The cylinder for a gas grill I can guess!

The 12 points from Germany go to ... Italy!!! :pir-sweet:

You are right, of course. In summer, we do the gas grilling almost every day - not that much on the meat side, but there are many things you can expose to heat - and they become very tasty. Thing is: Every time, I really make sure that everything is tight and good - gas-supply-wise - and when I press the piezo thingy to ignite the gas/oxygen mix flowing at some pressure through the bellows and pipes ... I sometimes think: Oh my. There are about 10 L = 2.5 gallons of liquified explosive gas in that thing ... then it makes puff - sometimes ffoomp - and - the grill is on. I should not watch these actions movies ... I am getting too old for that stuff  

When I charge my cell phone (a motorola g8 power - I bought that one because of the huge - uhmm - LiPo battery in there for 3 days of continued Zoom meeting operation - and the fast charging feature - while you zoom), it is never the same fear, in contrast: Can't this thing charge faster?

Phew. Apparently, France and Germany are playing soccer. Now that one seems to be the equivalent of 1000 gas grill cylinders, I guess. I am in the basement - putting another coat of paint on the door ... there is also beer here ... and some LiPo operated tools ... 

Here is to feeling good!    

 

3 minutes ago, legotux said:

we've learned from previous mistakes during all the centuries we dealt with petrol

And that is the point.

LiPos in today's main stream devices are safe. When we do experiment with them: Always be careful. As with the gas grill!

Best
Thorsten

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Any updates on this? 

How the runtime comparison?

It seems like you'd be able to even go with a 2x LiPO setup, or a single 26650. 

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