Garden Railway Forum

My GRS kitbashed Peckett loco, running on an LGB ToyTrain 0-4-0 motor block (with 24v Buehler motor) and powered by three 18650 li-ion 2.3Ah cells has just run continuously for 12h 40m!! I set her running while we entertained some friends for a meal, and I just let her carry on running until it got dark - and then ran her again the following morning until the battery protection circuitry stopped her (on 9.2v). My back of an envelope calculations suggest that she was only drawing an average of 0.18A, which I think is quite incredible, considering the Phoenix 2k2 soundcard was also active all the time.

When people ask me what sort of run time should they expect from li-ion batteries, I usually say "It depends ......... but you can expect to get 4-5 hours". Maybe I will have to revise my estimate.



Rik

Great run Rik. I am always amazed with the run time I get from my battery electric locos ( no sound card though)
even with NiMh batteries, although I am a fan of li-ion.on

Lovely scenic line Rik, nice gentle speed too, most satisfying.

ge_rik wrote: ↑Mon May 21, 2018 12:43 pm My GRS kitbashed Peckett loco, running on an LGB ToyTrain 0-4-0 motor block (with 24v Buehler motor) and powered by three 18650 li-ion 2.3Ah cells......... until the battery protection circuitry stopped her (on 9.2v). My back of an envelope calculations suggest that she was only drawing an average of 0.18A, which I think is quite incredible, considering the Phoenix 2k2 soundcard was also active all the time.
Rik

A really impressive low power loco.
And a nice relaxing video to watch.

I do have to be a bit pedantic though. The loco didn't take an average of 0.18A - the battery supplied an average of 0.18A.
Some of that went straight to the sound card, but the motor is supplied by a PWM controller. The PWM is a bit like a transformer - step down the voltage and you step up the current. So if you were only running the motor at one half of battery voltage, the motor current will be twice what the battery supplies. (ENERY in = energy out)
I know, I know, too complicated for most to worry about. Pulling head in now.....
Irrespective - it DID run for 12 hours. Fantastic!

gregh wrote: ↑Tue May 22, 2018 7:23 am

ge_rik wrote: ↑Mon May 21, 2018 12:43 pm My GRS kitbashed Peckett loco, running on an LGB ToyTrain 0-4-0 motor block (with 24v Buehler motor) and powered by three 18650 li-ion 2.3Ah cells......... until the battery protection circuitry stopped her (on 9.2v). My back of an envelope calculations suggest that she was only drawing an average of 0.18A, which I think is quite incredible, considering the Phoenix 2k2 soundcard was also active all the time.
Rik

I do have to be a bit pedantic though. The loco didn't take an average of 0.18A - the battery supplied an average of 0.18A.
Some of that went straight to the sound card, but the motor is supplied by a PWM controller. The PWM is a bit like a transformer - step down the voltage and you step up the current. So if you were only running the motor at one half of battery voltage, the motor current will be twice what the battery supplies. (ENERY in = energy out)
I know, I know, too complicated for most to worry about. Pulling head in now.....
Irrespective - it DID run for 12 hours. Fantastic!

Quite happy for you to be pedantic, Greg, and you're quite right. Terminology is very important - particularly when dealing with anything mathematical or scientific. I used to tell my students that, for example, saying "what is the difference between seven and eight" can be interpreted in several ways dependent on whether you are talking to a linguist, a mathematician, a sign-writer, or a six year old (or more particularly a seven year old, come to that).

Rik

Over twelve hours is quite impressive. I wonder if external temperature would make much of a noticeable difference?

Big Jim wrote: ↑Tue May 22, 2018 10:31 pm Over twelve hours is quite impressive. I wonder if external temperature would make much of a noticeable difference?

I'd imagine so, Jim. In fact, The Battery University says .....
"A battery that provides 100 percent capacity at 27°C (80°F) will typically deliver only 50 percent at –18°C (0°F)."

Mind you, I'm not planning to run my trains at -18C in the iminent future.

Rik