Battery Power

Geoff,

I have to say you out did yourself on this one. Excellent project. It has given me more ideas for my R/C battery powered experiments. I like the charging module and the use of the 3.7volt LiPo's.

Best article I've seen since your animated crane.  It's a definite 5 thumbs up article.

Bernd

Forgot to mention

Geoff,

Forgot to mention your ingenious way of fixing split gears. Got a chuckle out of your statement on some of the alternative methods you mentioned. Now I wonder where you got those from?

I'll have to give that KISS method a try. Much easier than turning rings to fit.

Bernd

@Bernd re: Comments

Hi Bernd,

Thank you for the very kind enthusiasm! 

With regard to the split gear fix, you should certainly recognize the bow to your expertise and others... and my own plight! If necessity is the mother of invention, then desperation may be the grandmother of invention! 

As near as I can tell this may not work if the split has propagated through the gear teeth themselves. After I put the "bindings" on, the split has not yet propagated farther along on any of the axles, so I am hoping for the best.

Have you watched the first video to the end? I was expected another comment from that too.

Best regards and have fun!

Geoff Bunza

The video

I watched it several times. I really like the performance of the engine. Nice and slow.

The whole article has much information to digest. It'll take several more reads to get all I can out of it. You should have run the engine and caboose on the plywood. That would have been a real treat.

As always nice and very thorough work on your part.

Bernd

I too also found the article

I too also found the article very interesting. I still think this is going to be the wave of the future.

Yes ...

... certainly a 5 star article; one of the most useful and interesting that I've seen in a very long time!  Thanks for putting this together.  

P.S.  On another note, I've gotten all my materials together now to try and put together your DCC decoder project (from another thread) ... just need a bit of free time ... not always easy to come by it seems.  :/

The future

As technology progresses, I am sure we are going to see improvements in batteries. This article and video are proof of concept and work wonderfully. It is still a little too much for me but I can see that in 10 or 20 years we will be wondering how we ever got along with just track power!

Batteries

There is already significant research going on to improve performance in batteries in several industries, including the automobile and R/C.  I don't think it will be all that long until we see some more compact, more powerful batteries that don't take too long to charge and aren't nearly as volatile as LiPos.

Lipos are not volatile...

if you follow basic common sense  in their application and use.  Do you consider a soldering iron volatile?  It can be if you walk out of a room and leave it plugged in unattended.   In my experience in the RC world, by far the major issues and accidents with lipos are caused by unattended charging.

Michael

Michael

They are "volatile" because of the adverse effects of misuse.  Overcharge a NiCd or NIMH, (or overdischarge one) and you don't have a fire.  Do that to a LiPo, and you very well could.  I don't disagree that used as directed they should be fine, but one forgetful moment, one silly mistake, and you could have a serious situation on your hands.  

LiPos also can be volatile when accidentally punctured or damaged, so they require extra care.  Can the risks be managed?  Absolutely.  I have 3 LiPos stored in my basement for my R/C vehicles, just as I have a soldering iron.  But I've seen both start fires, and thus I take certain precautions with each.  As I do with all power tools.  Like anything, it's about reducing risk to yourself, whether using gloves, safety goggles, face shield or whatever.  In case of LiPos, if you can get virtually the same performance for less risk, why wouldn't you?

Why Are You Using 30C RC Batteries?

With your very low current draw, why did you select RC High Rate Li Po's vs commercial lithium polymer cells rated at 1C-3C?

Cycle life of RC batteries is much lower than the 300 cycles normally specified.

With charging through the rail, they will never see high C rates, thankfully.

Very interesting article.  Anything promoting battery powered RC is good.

Pete Steinmetz

Battery Power

This is a very well written and informative article. But this  approach to battery power  is in my opinion far too complicated and costly. It most certainly is not an approach to Dead Rail. Those of us who started the Dead Rail Society  are truly that, Dead Rail - NO power in the rails. Converting to true dead rail eliminates all dirty rail, and wiring problems.   

Jim N.

Wireing

Mmmmmm.....

Except those in the motive power.

Bernd

 "Converting to true dead

I think the problem is finding the best balance between battery size in locos versus ease of use? A few easy to maintain powered track sections that eliminate the need for large batteries seems like a good trade off. Ideally powered track in all the easy to wire areas with small batteries or capacitors to allow operation on the harder to electrify track work areas seems like the best way to maximize layout simplicity along with loco space for speakers and other operating features. Why carry around more batteries than necessary for reliable operations?   .DaveB

Battery Safety

Hi,

Modelers have been working with products that California would likely plaster with warning labels since the first electric motor powered a tinplate locomotive around a strap-rail circle of track-- including spray lacquer paint, knives of all sorts including X-Acto knives and double edge razor blades (yes double edge), soldering irons and guns, machine tools of all sorts, hand wired DC power supplies connected to 120V AC mains, blackening and cleaning chemicals, asbestos mixes to strengthen plaster mountains, and the like. Through the years model magazines have even reported on the passing of modelers who did not pay close enough attention to safety-- I remember reading such. So a discussion of safety is always warranted, and those of us who have dealt with such things professionally can attest to this. I remember the long talk with a machinist (of 40 years experience) before I was allowed to turn on a drill press in our research group's machine shop.

BUT, knowledge, experience, and patience can go a long way to mitigate serious concerns with all of these... and have as such. LiPo batteries are fast becoming as common as an alkaline AA battery. They are in cell phones, tablets, and many, many newly designed rechargeable devices because they are lightweight, can be formed into many different rectangular shapes and sizes, carry a very high power density, and will often outlast the lifetime of the product in which they are inserted.

Power density simply refers to the total energy it can store per volume of battery. A higher energy density means it has more power in a small volume. LiPo batteries also can deliver great amount of current in a short time--so they can handle current demands of motors and transmitters. Dave commented of the large amount of research continuing to improve battery technology, and that is certainly true. The overwhelming focus is on increasing energy density. The rapid and uncontrolled release of energy from a high energy density item is commonly referred to as an explosion. So again safety concerns as batteries "improve" will be warranted.

That said. Lipo's need attention paid to charging, discharging, and physical use. There are many good references in both technical and layman's terms available for modelers to educate themselves on the web. By all means use them, study them, and learn from them. But realize that batteries can be a modeler's tool in the end, and as with many aspects of model railroading, it is likely not everyone's cup of tea.

You'll note that the batteries I used are never, repeat never directly connected to the electrical loads they power. They all have a "maintainer" circuit to isolate and protect them. The modeler does not need to extract the battery to charge it. In other words, once built you don't mess with the battery. Also battery charging is way below the max charging rate-- intentionally. There is just no need  for super fast charging here the way airplane RC modelers seem to want. These are operated well within specifications.

Again, safety concerns using any apparatus that may cause even incidental injury warrant the user educating themselves. While a modeler may not be interested enough to prepare themselves to use these themselves, they can and are being used safely everyday in ever increasing number. They are already ubiquitous.

Best regards,

Geoff Bunza

Using 30C RC Batteries?

Hi Pete,

Good question.-- real simple-- the 240mah batteries were cheap, plentiful, and the right size. They are never charged anywhere near the high charge rate-- I was trying to point this out in the article. With such a low charge rate, likely the battery life will be plenty long. By the way I haven't found one with a 1C-3C rate in that size.

Best Regards,

Geoff Bunza

@Jim N. Batteries and Dead Rail

Hi Jim,

As mentioned a couple of times, this may not be your cup of tea, but it may the lowest cost approach you'll find. If you take the time to research the components, they total less than the cost of a high quality boxcar!

This approach meets your dead rail requirements and does you one better-- it eliminates the car and battery handling requirements for recharging or replacing your batteries. You can operate on true dead rail as you like, and find a "charging rail section" to recharge without the "five fingered" intervention. Think of it as a special "programming track" for you battery powered models. Even better, just power a large section so that they'll recharge enough on demand as you operate-- again no intervention and completely automatic and regulated/controlled on board.

Also if need be, the transmitter could easily be controlled via a DCC decoder with a little extra work. The buttons could correspond to functions, and the speed set from the decoder could be converted and sent as a speed set number, as it is done in this project. It simply was not something I needed for my project.

If not convinced about running on dead rail, here's an early video with the loco running on styrene rails:

Think of it as dead rail with benefits!  Have fun!

Best Regards,

Geoff Bunza

Batteries

Geoff,

Since we are on the subject of batteries Geoff. I have a question. You show the use of a single 3.7volt LiPo. What if I wanted to use the next up, say a 7.4volt LiPo. Will the charger you designed charge both batteries and how would they be wired? Would this entail a different charging circuit than the one you designed?

Reason I ask is that I want to use the full 6 volts on the railtruck since the motor will top out a 6 volts. I guess what I'm asking is can your charging circuit be used with higher voltage, 7.4 volt LiPo, to charge the battery or batteries?

Bernd

Building light program

i have been looking at this idea for a while thank you for getting this out problem now solved. great article!!!!!!

Batterries for Bernd

Hi Bernd,

Short answer-- no you wouldn't want to use this circuit for two reasons: first the charging voltage would not be high enough, and the second opens up the issue of charging multicell LiPo batteries (as the 7.4V LiPo is actually 2 cells in series). Over time it is likely that the charge/discharge characteristics of each cell would differ enough that one cell would reach full charge before the other, potentially damaging the cell with an overcharge situation. It is for this reason that multicell LiPo chargers typically are found with connections to each cell in a multicell battery to monitor and correct for this situation. If used properly this alleviates the concern. I have seen mulicell charger modules but have not pursued this path as of yet.

You should note that the second battery loco is equipped with a slightly different design that uses a more robust variable DC-DC converter that can easily put out 6-15 volts. This will of course draw the battery down faster since you don't get the added power for nothing! However, you can use a larger single cell LiPo in any of the designs presented if physically possible, say a 1400mah single cell, which will give you about 5 times the power stored and last much longer. It will also take longer to charge to full power. This was exactly why I offered this last, alternative approach-- and it's simpler. I like simple and cheap!   

Best regards,

Geoff Bunza

@Mike D

Mike,

I'm not sure if you're talking about battery power or building lighting animation?

In either case, I'm glad you liked it! 

Best regards,

Geoff Bunza

Thanks Geoff

That's what I thought, it couldn't be done. I'm not to keen on dc-dc converter yet.

Again thanks for the conformation.

Bernd

Still take exception....

...to lipo batteries being referred  to as "volatile". Makes them sound like they are unstable or something. As with anything, a little common sense  in their application and handling goes a long way.  Of course, I may be asking a lot to ask people to employ common sense. In this day and age it seems to be somewhat of a lost commodity.

Michael

Charge rate

I would like to make a small but very important correction to the article. The 30C rate is the DISCHARGE rate, and NOT the CHARGE rate. i.e. You can discharge a 240mAh cell at 0.24 * 30 = 7.2A safely. But, never charge LiPos over a 1C rate (i.e. 240mA). There are a few LiPos which can tolerate 2C or even as high as 5C charge rates but they will be specifically  marked as such. If you charge a LiPo at 30C rate there is a very good chance that flames and toxic smoke will come pouring out of the battery. I've seen this happen from only slightly larger packs and the flames shoot out about 2 feet, and that is without puncturing the cells, just by overcharging using the wrong charger setting. The charger linked to on eBay will only output 450mA so this is unlikely to cause much in the way of flames fortunately, especially if not discharging the battery too far so it is only trickle charging the cell at low current, but anyone reading this article and thinking of using larger batteries and chargers for larger projects like G scale needs to be more careful when selecting a charger to suit their battery. A safer battery to use might be a LiFePO4 but again, they need their own special charger and cannot be charged with a LiPo or Li-Ion charger!

p.s. The batteries in phones and laptops are NOT LiPos. They are Li-Ion, which are quite a bit safer than LiPo!