So far, I have converted three locomotives. A Spectrum 2-8-0, a Spectrum 4-4-0 and an old DC Camelback 2-6-0 that I picked up at a garage sale.
The Camelback wouldn't run well on my electric test track but that problem was obviously related to a electrical pick-up problem
They all run pretty much the same way on battery power.
Wonderful (the only applicable term) slow speed movement. Low top speed but that's what I was looking for anyway.
Good pulling power.
The 4-4-0 derails the most easily on uncertain track but has been much better since I added more weight.
The 4-4-0 also has the lowest pulling power before I get wheel spin but Bullfrog Snot is on the way.
The Camelback will run through complicated track the best, has the most pulling power and is the best switcher.
I am getting progressively better at the entire conversion process.
I'm using 2 cell Lipos in each of the three units plus Del Tang 62's receivers purchased from Andy at Micron.
Which all leads me to running times.
I would suspect that I can tell you today that they'll stay running and constantly operational for approximately an hour and ten minutes.
How does that fare with everyone else's experiences
In my case, I have six more locomotives to convert and I believe the seventy minutes of run time per unit will be probably be enough for my operational purposes.
It is all a matter of the loco's internal friction and motor efficiency.
Take the current draw @7.5V when running idle, and multiply that with 1.25 ( for intermittent train loads ) or 1.5 ( for full-time train load ).
Divide the mAh of the cell by this and multiply the result by 0.8.
Then you'll have an educated guess of achievable run-time.
It cannot be stressed enough that a well-running mechanism together with an efficient motor are prerequisites for a satisfying performance.
I checked the loco current draw a different way.
I ran the loco pulling a full load on my continuous run layout using either a single or pair of 100mAh lipos plus Pololu regulator.
I timed how long it was before the low voltage cut off operated and from this I could calculate how many milliamps the loco was drawing.
How big a battery do you need?
I can run several locos in a 2 to 3 hour running session and I have developed a 'standard' way of calculating battery size.
Take a 4-6-2 Express loco pulling 12 coaches, mine draw up to 400mA.
30 minutes run time and 2.5 hours idle time is the norm.
The loco needs 200mAh for running and 50mAh for idling giving a minimum battery size of 250mAh.
Practical experience shows the loco run times are nearer to 15-20 minutes than 30.
My four small 0-4-0Ts have Bachmann "Thomas the Train" Percy mechanisms, two cell 300 mah Lipos with a Pololu 9 volt step up regulator.
Operating sessions are three hours and they generally use only about 1/2 their charge during a session.
That is not continuous running of course as the operation is mostly switching.
My continuous run tests have shown they will run almost three hours.
The motors are very small and they usually are only pulling three to five light four wheel cars.
The Bachmann HO F7 I converted has the same equipment and after a three hour operating session with a switching assignment it used 260 mah of the 300 available.
I'm O scale and normally get 2.0-2.5hrs run time, but that's using 2000Mah, 9.6v-12v NiMh or 2200Mah 11.1 LiPo battery packs.
I probably could use smaller batteries, but the cost is near the same and as long as they fit inside the tender or engine, the bigger the better.
I would say what you're getting is correct.
I have a 3rd Rail E7 that was draining the battery more quickly.
I found some parts rubbing on one another.
It also has a belt drive and I think the belt was too tight or misaligned.
I loosened the screws holding the motor and mount and when it felt right I tightened them up.
Engine is not as loud now but I haven't run an endurance test yet too see how long it runs on a full charge.
I allow 20mA per hour for a Rx/Pololu combination which is switched on but not moving a train, 15mA for the Rx and 5mA for the Pololu.
The Pololu is about 80% to 90% efficient and 2 lipos delivering a nominal 7.4V is more efficient than a single lipo delivering 3.7V
I also have 3 heavy freight locos which use 7.4V and no Pololu and they can haul a heavy train at about scale 30mph which is all that is needed.
Maybe your locos have efficient motors that don't need many mA.
Or maybe I'm being too optimistic.
I have not done exact science on this "run time" experience, just an approximation.
Ran trains earlier this evening with grandchildren though and we were able to operate for an acceptable time period.
(they weren't bored yet where they were summoned for dinner)
Trying to complete the trackwork for remainder of the layout
(this is a new layout and the tracks are only half in)
although there is indeed enough there for a customized switching list.
I installed a photo backdrop of Brockville Harbour on the first section of the layout,
and am awaiting the arrival of a forested photo backdrop of actual track view between Irish Creek and Bell Crossing,
to represent the remainder of the area that runs through the countryside.
There are sections that require this backdrop installation to occur first before I can proceed with the remainder of the benchwork/track etc.
In the meantime I have been working on other secondary stuff.
Received four additional transmitters this week from Micron.
Lots to do.
I have so much to do that I hardly have time to run trains!
I started the layout over 4 years ago and the track laying is complete and a fair amount of the scenery.
I am constructing platform canopies at the moment.
I think it will take until xmas
Back to the run time issue.
I don't worry to much about it now as it meets my boredom limit of up to 3 hours.
So it has passed the 'bored kid' test.
I must ask Micron a price for providing stuff with ready attached SIL sockets rather than wires.
This would make installation easier.
They were very helpful with custom made flexible battery leads.
I agree that Micron has been great.
They ship air mail to me and I receive their products in reasonable time.
Sometimes I cringe when I email Andy because I usually forget about the time differential.
But he's always Johnny on the spot to reply.
By the way, I notice that I have an antenna missing on one of my receivers and yet the locomotive still operates very well regardless.
The layout room is 18' square.
Perhaps, it's simply a small enough area and therefore transmitter stays connected.
But, it's also probably enough of a walk-around track plan that I suppose the operator is invariably close to his/her locomotive most of the time.
I will try backing up through the door to see how far the transmitter's connection actually reaches on the antenna-less unit.
Working on the peninsula benchwork which is complicated enough for my limited IQ.
A backdrop will split the peninsula and one side will present trackage at a higher elevation.
Therefore trying to figure out the base height of the benchwork that will fit all needs.
Have drawn diagrams from all directions but am simply going to have to bite the bullet and actually "do it" and then correct my mistakes afterward.
The Walthers turntable mentioned previously in an earlier post turns a little too quickly for my tastes even at the lowest speed of the old transformer I bought to power it.
That was one reason I was hoping to use a straight two cell Lipo as I thought it would turn more slowly on less voltage.
Jury still not out on what I will do.
But at least turntable up and running.
I'm operating at point to point and will require three turntables.
I will want them all running slower than this.
Why couldn't I wire in a DelTang receiver to the turntable motor and then run it with a two cell Lipo and a DelTang transmitter?