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[Peterm]

A question for the model motor experts, eg, FLJ.   I am using a couple of 380`s, I think 3 pole, on 7.2 volts.   There are no markings to indicate manufacturer or voltage rating.   If they are rated at 7.2volts and I uprate the voltage to 8.2 volts, is it likely to do much damage?   Advice, please, and thanks.   Pete M

[Shipmate60]

Model boat motors are sourced for lots of different places and manufacturers, so almost impossible to answer unless you have some data on the specific motor.
BUT
Most model boat motors are quite lightly loaded most of the time.
You could try connecting up to 8.4 volts and see if the motor gets hot, if it doesnt it is worth the risk, if it gets hot then dont use 8.4 volts.

Bob

[DickyD]

I have the same trouble with my Scheutze. It has two completely unmarked motors which came with the running kit from Robbes.
They recommend 6v batteries I am running with 9.6v batteries with no trouble. Motors are running cold.
Try it a little at a time.

Richard

[Peterm]

I guess the answer is really `suck it and see`.   Thanks anyway, Pete M

[FullLeatherJacket]

Pete
You know the old adage about "experts" ...... has-beens and drips under pressure? Me. Any expertise I have picked up was from exactly the same
source as Bob and Richard i.e. "I'll have to remember not to do that again......" The 3-pole 380s are the beasts of that case size - Graupner call them Speed 400s and that's a good term. They are very quick and very efficient, and are rated by Graupner according to their voltage. Usually the lower the voltage rating then the hotter is the motor. I have a 20" balsa Fairey Swordsman which uses a 7.2v Speed 400 and it flies!! Graupner make great use of these in their geared units, which are very reliable and easy to install. The other good thing about the Speed 400 range is their price. 385s on the other hand are nominally 12 volt motors and would be hard-pressed to pull  the skin off a rice pudding on 7.2 volts. Best for multiple installations like grey-funnel jobs, or small/slow workboats. 
Bob is dead right when he says it's hard to identify one motor from another. I'm trying to find a reliable way of measuring the RPM of these little monsters so I can at least put out reliable bullsh1t if anyone asks!
Suit yourselves.
FLJ

[HS93 (RIP)]

You can use long probes to measure the resistance of each pole from a known source.

Peter

[Peterm]

North and South from the equator?  Pete

[wombat]

The other thing to watch is the commutator - as you go over the rated voltage for the motor, the current and the transients through the brushes will increase - this could speed up the erosion and wear on them.

Wom

[DickyD]

The other thing to watch is the commutator - as you go over the rated voltage for the motor, the current and the transients through the brushes will increase - this could speed up the erosion and wear on them.

Wom

Dont think I could get my head in my boats to watch that.

Richard

[Model Boats Website]

A question for the model motor experts, eg, FLJ.   I am using a couple of 380`s, I think 3 pole, on 7.2 volts.   There are no markings to indicate manufacturer or voltage rating.   If they are rated at 7.2volts and I uprate the voltage to 8.2 volts, is it likely to do much damage?   Advice, please, and thanks.   Pete M

The answer is that it wont do much damage, in the past I've used an 8.4v battery on a Groupner 7.2v motor. The motor didn't get too hot although I wouldn't suggest going around at full speed for any length of time.

[Shipmate60]

FLJ,
I have a small hand held tacho which works fine as long as the coupling end is on the outpup shaft.
I also connect into the power line a voltmeter and ammeter wired up to single tamiya plugs both ends.
This makes motor readings and speed so much easier.

Bob

[cbr900]

I use an aircraft Tacho which gas two three and four blade switch, connect a prop and turn on, seems to be reasonable accurate....


Roy

[chromedome]

I can recall down the engineroom on a Loch class converted to a Bay class frigate,waiting on a big end to slap me on the palm of my hand so I new how many revs we were doing....I understood that!!

   chromedome