Battery power questions!

I'm thinking of buying a couple of rechargeable 9v 250mah batteries from the Conrad catalogue; they come complete with charger and I'm wondering if they may be the answer to my problems! Three of my locos are LGB with 12v motors, I only want to pull a couple of coaches and perhaps a wagon as per 1910 prototype. the problem is i cant get them to go slow enough to look realistic through the town. Would less voltage drive the motor, but slower?

mikey

Are you sure they are 12v motors Mikey as LGB are usually 22v or there abouts, but Yes less voltage slower, but probably drawing more amps.

Must admit i just presumed they were 12v Peter. they are all converted stainz's and I normally run them with a trailer wagon containing an old drill battery of 14volts. They run fine but just too fast for my liking

mikey

Have you got anything that would give you 9v to try?
If you did get them and you had the room, you could run the 2 x 9v batteries in parallel to give you twice the run time i.e. 500mah

9V should give you a relatively sedate speed. I assume you wouldn't be hooking these up in series, which would yield 18v and would indeed make for fast movement. 12-14v generally yields an acceptible top speed in most LGB locos. I think LGB use 22-24v motors for two reasons: More volts help push the electrons through dirty track/wheel, and little kids (and some big kids) like to run their trains fast.

You could verify the speed at 9v before ordering from Conrad by simply buying a 9v alkaline battery at your local Auchan/Leclerc/Carrefour/etc. and connect it to see how fast it runs. This won't be exact, because the 9v rechargables will likely be either 8.4 or 9.6 volts, since NiMH and NiCd cells are nominally 1.2 v each, but it should be close. BTW, 250 mAh batteries won't give you much running time. I generally use 2000-3000 mAh.

If 9v still makes your trains run too fast, you can use a resistor (a big one rated for say 5 ohms and 5 watts) in series with the motor to step down the voltage. You can also use diodes in series (a la Carl Hibbs and his vibrator) or build one of the speed control circuits using a darlington transistor mentioned in the forum from time to time. As I recall, Carl has offered to build these for other folks before. You could also apply any of these with your 14v drill batteries.

My name is mentioned in vain....

Mikey have you still got the speed controller for the drill?

If you dismantle a cordless drill (a variable speed one of course) they have a robust sprung linear pot actuated controller.

With some ingenuity you could rig that up with a lever or something.
I have one in my spart parts skip.

I also have another vibrator controller too. This one is from a big black heavy duty angled thing(labelled Dr Johnson.... ) that is no longer required by it's former user.