Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: flag-d on July 29, 2006, 02:25:47 pm
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I have 2 (identical) electric motors I acquired some years ago (10-15?). Is there a way of identifying them at all? There are no identifying marks on them at all. They are permanent magnet type with a fairly open casing at the back, 5mm shaft, around 40mm diameter and some 75mm long (not including the shaft). I know it is a long shot, but can anyone help? I could take a photo if that would help (which in itself won't, of course, but I could post it on here, which might!)?
I ask because I'd like to fit one into a 36" Thorneycroft MTB and, without considerable experimentation, have no idea as to battery voltage or ESC rating to use. Neither motor has been used, at least by me, though I remember I did swap them for a pair of HUGE (around 120mm diameter!) black MFA motors.
Anyone any ideas?
Mike
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Here are some photos of the thing in question...
Mike
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Mike,
Are the motors 3-pole or 5-pole?
Tony
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They are certainly old, just look at that cappie..
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ITT very old.
Why don't you do some tests on the motor.
see what voltage it runs best at.
has it good torque
what revs are available.
another things is can you get replacement brushes
hopefully you have the body covers
be interesting to see the results
martin
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Tony: a lot more than 5 pole, I'll have to count them tonight.
Seaspray: Loads of torque, high revs (well, it whizzes around quick!), no covers (never had any) and the brushes are replaceable.
Mike
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In that case I would go for it .
You didn't say the voltage it was running on
somrtimes old ones are good I've got an old one (ford rad 1987) in the battleship and it keeps on going.
martin
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Mike,
Deferably sound OK, especially since I had to gear my 540's down on my Thorneycroft. The extra torque/lower revs (generally) of the multi poles should mean that you should be able to run direct even though the hull is quite heavy in the water.
Tony
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Yes Paul, they are 12 pole types. Come to think of it, the shop I got them from (long since gone now) did say that they were Germna, so I guess they could well be the Bosch ones.
Thanks one and all
Mike
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They look like a Robbe Elt Max 30
http://www.modelbouwforum.nl/phpBB2/viewtopic.php?p=590406&sid=be1fe89721d3c37e812b5c8dd27a5713
Mark
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Hi just a quick 'rule of thumb' If you can measure the stall current (this could be quite high) then operate the motor at 20% of this current (same voltage) and it is probably running at its most efficient speed.
regards Roy
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Your motors must have an odd number of poles to be self starting. Count the number of poles that the wire is wound around, not the number of commutator plates. Chuck the motor shaft in a drill press chuck, connect a volt meter to the motor, hold the motor and turn on the drill press. Take note of the voltage reading. Divide the drill press' RPM by the voltage. This will give you the motors RPM's per volt rating.