On board LiPo charging

I have an HO deadrail layout. I have been using 2 cell lipo batteries to power my locomotives. It is difficult to fit a 3 cell lipo battery into the tenders of my steam engines of which I have nine. The locomotives run fine on a 2 cell lipo battery with 7.4 volts of power. The only impact of 7.4 volts is a lower top speed. On the topic of onboard charging of lipo batteries, I believe it hasn't truly been sorted out by any one in real life. i have read a number of articles written by armchair academics and dreamers and haven't seen itdone on an actual functioning layout.

I remove my lipo batteries individually for charging. (By the way, I get approx two hours of operation with a fully charged lipo battery using Del Tang receivers and transmitters with the two cell). Takes me literally ten seconds to remove each battery from it's tender. Then I charge the batteries three at a time while watching television.

Hope this helps.

Rick Dow

With regard to charging multiple batteries ... I have not yet tried this, but if you use 'protected' lithium batteries with the in-built over-charge (and everything else 'Over') it should be safe to charge multiple batteries wired in parallel, since, if one battery finishes charging before the other, its protection circuit activates until the other battery is fully charged when ITS protection cuts it off, too. I stress that this is only theory at this point. I will post again after some tests.

Rj Ws

Thank you Ken and Peeyush,

Thank's for all the information and links Ken.

I agree and understands that ALL types of LiPo batteries needs a balance charger onboard. (That was, was I was asking for ;) )

But the Amrit™ is the answer to it all, when it appears to customers.

With a larger battery it is exactly what's needed.

No balancing is needed, because it's just one cell, and I presume it has all the "step-up" electronics and charging circuits ready made on the board.

The Magnetically Activated Switch would also made it easier to install in any locomotive, no need to put in a switch.

Thank you Peeyush. :)

Just to clarify:

My RC electrically powered RC plane site is:

http://www.theampeer.org

and the HO train part is

http://www.theampeer.org/HO

Hi Dandelion,

On board LiPo charging requires an onboard Lithium Polymer battery charging circuit, even for just a single cell LiPo battery and a “balancing circuit” for resultant batteries with more than one Lithium based battery.

Lithium Polymer, as well as other Lithium based batteries, require a two step charge operation. First there is the constant current phase and then a constant voltage phase to a predetermined cut off current, usually 1/10 the current of the constant current phase. This is known as CC/CV charging.

EEVblog #176 - Lithium Ion/Polymer Battery Charging Tutorial

https://youtu.be/A6mKd5_-abk

I believe the idea for track charging started when some folks were using rechargeable NiCad and NiMH batteries to power their locomotives. You can get away with just charging NiCad/NiMH directly, for awhile, but a “real” NiCad/NiMH charger uses a characteristic of those chemistries that Lithium based batteries do not have. When a NiCd or NiMN battery reaches fully charged, the voltage actually does a little drop. Circuits for peak charging NiCad and NiMH batteries look for that peak and drop to stop charging those types of batteries.

Trying to do direct charging of Lithium based batteries, except possibly LiFePO4, doesn’t work well, or safely.

Another characteristic of Lithium based batteries is that when they are grouped together, that is physically connected, to make a resultant battery with more than one battery, the batteries, no matter how closely matched originally, will become unbalanced during discharge. That is why “balance charging”, by removing the energy from a battery, or batteries, of a resultant battery, is used to allow the “lagging” battery to “catch up”.

Lithium Polymer pouch (LiPo) batteries fall into the the Lithium Cobalt Oxide (LCO) group. The LCO type battery is the least safe, most volatile, of all Lithium based battery chemistries.

BU-205: Types of Lithium-ion

https://batteryuniversity.com/article/bu-205-types-of-lithium-ion

and

BU-206: Lithium-polymer: Substance or Hype?

https://batteryuniversity.com/article/bu-206-lithium-polymer-substance-or-hype

“The majority of Li-polymer packs are cobalt based…”

That is true for RC power pack type LiPo batteries.

There are also some pouch batteries with LiFePO4 chemistry, but mostly 2 cell packs for use in RC transmitters, with a few exceptions.

I recently archived a lot of information on my Website. In the archive I have a section titled “Comparing Lithium-ion Batteries”. It might be helpful here.

https://theampeer.org/HO/#ARC30

I originally thought that having a LiPo in the locomotive was the way to go. Once I gained more knowledge about all the options available to me, cylindrical Lithium based batteries, in a “trailing car” made more sense to me because of their better relative safety and because it is very easy to change or remove batteries for charging with a well planned and executed trailing car.

With the Lithium based cylindrical batteries removed for charging, they can be charged on a proper Lithium based battery type charger that can charge 2 or 4 batteries at a time, and since each battery is being individually charged, there is no balance problem to overcome.

At this time, it appears, through EXTENSIVE YouTube and Google searches, that I am the only person using cylindrical Lithium based batteries in a trailing car for HO or any other scale. I truly believe that this is the safest way to go, especially with my latest conversion.

The CSX With the Boxcar Battery Car Converted to LiFePO4 Batteries

https://theampeer.org/HO/#LIFE

Just my two cents worth,

Ken