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Revisiting 1-Cell Versus 2-Cell Li-Po Batteries
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 Posted: Mon Apr 4th, 2016 07:46 pm
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mwiz64
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If you raise the voltage, you lower the current draw for a given work load...at the motor but sometimes a different winding on the motor is necessary to take advantage of the higher voltage, do to the KV of the motor. Of course, the opposite is also true. If you run a lower voltage, the current draw will be higher for a given work load..... and your battery will run dead quicker. Voltage boosters, as you've seen, use up energy. There ain't no such thing as a free lunch. Run the voltage you need from the battery and skip the booster, if you can.... even if it means running two really small cells. Or at least be open to giving that a try. You might just be surprised at the duration of the charge. Higher voltage is more efficient.



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 Posted: Mon Apr 4th, 2016 08:26 pm
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W C Greene
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Yes, I agree with Mike on this. But then, I always find room for the batteries, it's called "creative cramming".

Woodie



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 Posted: Tue Apr 5th, 2016 11:19 am
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davecttr
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As I am running 00 scale finding space for the batteries is the main challenge so a single cell solution is attractive. For most of the locos a single cell with a 9V regulator works just fine and I can get up to 1hr of use before battery replacement (I recharge my batteries outside the loco). For some of the locos drawing 0.4A or more I use 2 cells in series with the 9v Pololu booster, again 1 hour run time is possible. Two cells giving 7.4V does not give a high enough top speed and 3 batteries occupy to much space. For some pairs of locos a regulator is needed anyway if you want to consist them. I also don't like the top speed reducing as the battery discharges.



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 Posted: Tue Apr 5th, 2016 06:27 pm
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mwiz64
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The other solution is to get the MFG's to offer motors wound to turn faster so the lower voltage gives the performance you need. It's a simple thing for them to do. Just put in thicker wire and fewer winds.... or look for suitable motors that are already made with "hotter" windings. One could also change the gearing... I'm not saying these things are easy to do, just that they are possible solutions to running lower voltage.

And Dave, I'm not saying what you're doing is wrong. I'm pointing these things out for other people, that might be reading this thread, to consider. My models are larger so I can find space for more cells in the battery.

Last edited on Tue Apr 5th, 2016 06:30 pm by mwiz64



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 Posted: Tue Apr 5th, 2016 06:33 pm
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W C Greene
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Yes, I have the space...1:35n2...so I use what will fit. Normally I use 2C 1200MAH or so Li Pos. On a point to point layout with plenty of switching, a lower "top end" is just fine. Someday, battery technology will catch up with OO9 and even N scale but in the mean time....

Woodie



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 Posted: Tue Apr 5th, 2016 07:46 pm
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mwiz64
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One of the things that helps you and I out, Woodie is that we model subjects that run pretty slowly in the first place



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 Posted: Tue Apr 5th, 2016 07:56 pm
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davecttr
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Here in the UK 00 scale means basically locos produced by Hornby and Bachmann with some other smaller manufacturers. They are all designed to run on 12VDC and the DCC 16V? ends up about equivalent. So no chance of them substituting lower voltage motors. A direct plug in replacement can motor would be ideal, 6V might work well.



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 Posted: Tue Apr 5th, 2016 09:34 pm
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fallen
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As Rod says, changing the motor and gearing can be a bit of a challenge, but if the problem is that the motor is old, either old and worn or just an old design, then changing just the motor, not the gearing, can work OK and may be less of a problem.

I have done this on a couple of n gauge chassis for 009 locos and it has worked well.

Frank

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 Posted: Wed Apr 6th, 2016 05:05 am
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mwiz64
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NWSL sells several replacement motors and publishes their RPMs at 12v. They also sell replacement gearing sets.

All you have to do to check the speed of your motor is take it out, put a makeshift, paper or stick propellor on it, run 12v thru it and tach it with a model airplane tachometer you buy at the local hobby shop. I know, that's not super easy but if you're going to re-motor anyway, why not figure out what you have in the first place?



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 Posted: Wed Apr 6th, 2016 05:07 am
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mwiz64
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BTW, adding one more tooth on a pinion can be easy enough and make a big difference.



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