A new duration record for battery power?

[whatlep]

Yesterday was Christmas Day so naturally our tree had some G scale running round it. The train of a Stainz loco and 2 LGB 4-wheel coaches was started at 11am and continued circling a 600mm radius circle for at least the next 10 hours. The actual running time was a little more, but nobody noticed the time, shortly after 9pm, when it finally exhausted the battery. The train was powered by a 6800mAh Chinese Li-ion battery via a Cliff Barker control system.

So, is 10 hours a record for battery duration? Over to you lot!

Armed with my new Christmas watch/ chronograph and a calculator, the following statistics may keep someone happy for ages.
Track radius 600mm = circumference of 3.768 metres
Average circuit time 67.1 seconds over 10 hours = 536.5 circuits
536.5 circuits at 3.768 metres = 2021.58 metres actually travelled (over 2Km!)
Scale distance travelled (@ 1:22.5) = 45.5 Km

Now I find it interesting that in 10 hours the loco had only travelled at an average scale speed of 4.5 Km/hour. It looked slow indoors, but not that slow! Perhaps all of us are running our G scale rather more slowly than we think? :thinking:

 

[stockers]

Perhaps all of us are running our G scale rather more slowly than we think? :thinking:

I think you may be right. I like to run mine slowly - to see the motion working and the sound sounds though the loco is working hard.
If you watch the real things, the motion is often little more than a blur and the exhaust sound is usually a very rapid beat. Even when slowing for a station stop the connecting rods beat up and down very rapidly.

 

[Zerogee]

Actually Peter, over a minute (67 seconds) to do one lap of an R1 circle sounds pretty slow to me - barely more than a crawl, about 2" per second?

I'm sure you're right about many of us being rather hung up on slow-speed operation so that we actually run at much less than scale speed; if you reckon on a typical real-life narrow gauge line being restricted to (say) 15km/hr, which is hardly fast after all, that would still be over three times the speed you were running the Stainz at. Then there are all those videos of 2095s going like the clappers so that their whizzy cranks are just a blur....

Interesting result on the battery life - I wonder if increasing the speed (double or even treble) would have resulted in a greater or lesser overall distance travelled?

Jon.

 

[whatlep]

Interesting result on the battery life - I wonder if increasing the speed (double or even treble) would have resulted in a greater or lesser overall distance travelled?

Well, it would be rude not to find out! I'll get back to you via this thread.

 

[yb281]

Very interesting test this (and held in laboratory conditions of course!), but the result doesn't surprise me. It was quite common during the Summer (ha!) for me to get a month's running out of my Corpet with the same type of battery in normal service on the WGLR in between charges. Even then I re-charged as a matter of course rather than because the battery had gone flat.

 

[Del Tapparo]

6800 mah is a huge battery. 6.8 amp*hours / 10 hours = 0.68 amps draw from your loco. Sounds about right. I normally use 4800 mah, but will be using 6800 mah for a public display that will possibly be operating for 8-10 hours per day.

 

[whatlep]

Well, this evening the train ran again. Started 16.55. Stopped 23.47. I make that 6 hours 52 minutes.
The speed had been increased so that a circuit of the 600mm radius circle took 27 seconds. Now that only equates to a paltry 11.5 Km/hour scale speed, BUT my daughter wouldn't allow me to let "her" Stainz run faster. Presumably on an ultra-small circuit in a confined indoor area the illusion of speed is increased?

Anyway, there you are. If I can find a time when SWMBette isn't around, I'll see if I can run the little beggar at Warp speed!

 

[Zerogee]

Useful info, Peter - you might want to check my calculations, but I make that approx. 915.5 circuits of the loop, = approx. 3477 metres actual, or over 78 scale Km!
So, running more than twice as fast almost doubled the distance covered on the same battery charge.... a very interesting result, which implies that increasing the speed does not increase the loco's amp draw in anything like a linear fashion.
I guess there must be an optimum speed for greatest motor efficiency, but slower is certainly not more efficient.

As Spock would say: "Fascinating, Captain...."

Jon.

 

[whatlep]

Useful info, Peter - you might want to check my calculations, but I make that approx. 915.5 circuits of the loop, = approx. 3477 metres actual, or over 78 scale Km!
So, running more than twice as fast almost doubled the distance covered on the same battery charge.... a very interesting result, which implies that increasing the speed does not increase the loco's amp draw in anything like a linear fashion.
I guess there must be an optimum speed for greatest motor efficiency, but slower is certainly not more efficient.

As Spock would say: "Fascinating, Captain...."

Jon.

Were the figures spot on, I'd agree absolutely, but there's the complicating factor that over time the loco slowed slightly as the battery lost power. Every time I checked the lap time and found the loco had slowed, I adjusted the speed back to the original level. I don't think the effect was so pronounced at the first test's slower speeds, but I didn't have the chance to check. Anyhow, the train certainly did fewer laps than the figure of 6h52m divided by 27 seconds would generate.

Clearly the diminution in running time is not linear, but without more tests, all I'm prepared to say is that I still claim the prize for elapsed time from the first test!

 

[Tony Walsham]

Surely a comparison test of time elapsed for milliamps used, would be a more valid comparison.

Some years ago I was testing a Bachmann 0-4-0 side tank loco with 14.4 volts of ENELOOP 2,000 ma hybrid AA's and managed 5 hours plus on rollers.

 

[whatlep]

Surely a comparison test of time elapsed for milliamps used, would be a more valid comparison.

Some years ago I was testing a Bachmann 0-4-0 side tank loco with 14.4 volts of ENELOOP 2,000 ma hybrid AA's and managed 5 hours plus on rollers.

Understand your implied point about battery efficiency Tony, but for me it's how rarely I have to recharge the batteries that's important. To date, no NiMH cells have come close to the run times I get from Li-ion.

 

[New Haven Neil 2]

Thread drift alert - scale speeds.....

Drives me nuts when I see a rivet counter model at an exhibition shunting at 1mph. As a keen observer of such things in my youth, it was done about as fast as possible, screeching stops and reversing before the buffers had time to spring out and rattle the wagons. I'm all for scale speeds, but some folk can't translate it to their models, not sure if that is because they haven't ever observed the prototype in action, or they don't have the spacial awareness to appreciate the model speeds. Fitting a bicycle speedometer to one of my G scale wagons and calibrating it to scale speed revealed I run my steamers at about 15 mph, spot on for the Talyllyn, maybe a bit slow for the Ffesterbahn! /thread drift.

I really should see how long my little IP engineering Punch will run on a charge of it's AA cells, I only seem to charge them once a year! One for the spring when I'm more mobile.

 

[yb281]

Anyway, there you are. If I can find a time when SWMBette isn't around, I'll see if I can run the little beggar at Warp speed!

Of course one of the other advantages of battery power is that you SHOULD be able to reach sufficient speed to corner on 2 wheels. I remember a test some years ago in Bolton when a certain Z mate was able to get his eggliner on 2 wheels, but (being track powered) it immediately lost power and was unable to maintain this Colin McRae stance. Not entirely prototypical operating of course, but I laughed so much I got a headache ...... and it IS still (sort of) Christmas after all?

 

[whatlep]

OK, I've just tried to get the Stainz circling with a lap time of 15 seconds and have given up. The amount of noise was even worse than the CD my daughter received for Christmas. Indeed so loud that within 10 laps I received a yellow card from both SWMBO and SWMBette. The Stainz is now circling at a much more sedate pace. Oh well....

 

[CoggesRailway]

lol. Excellent commitment Peter. I read this early this morning and decided to test my 2095. It's got endurance but can't keep it up like your Stainz can.

If this recession ever ends and the good times come back for us salesmen I think I would go all RC and Li-ion.

The real test for battery power is when you feel like running and you haven't bothered to prepare anything from last time it will generally run as opposed to generally die. Ever the scientist me.

 

[whatlep]

lol. Excellent commitment Peter. I read this early this morning and decided to test my 2095. It's got endurance but can't keep it up like your Stainz can.

If this recession ever ends and the good times come back for us salesmen I think I would go all RC and Li-ion.

The real test for battery power is when you feel like running and you haven't bothered to prepare anything from last time it will generally run as opposed to generally die. Ever the scientist me.

First he's a salesman, then a scientist. Bet you got an "ology" for Christmas!