Dissection of a Titan 12T Motor

[Hoghappy]

Since I have a couple of cooked Traxxas Titan 12T motors laying around, I thought it would be interesting to take one apart to see what it looks like and what melted. This is the Titan 12T available at a number of places for an approximate cost of $22.75. I pried the can open with a pair of pliers and a screwdriver. Checked it out and could not determine what part failed....I expected to see melted wires...but did not. :confused:

Capt. Crash

[toesup]

Ahhhhh...
But can you put it back together?... :p

[woodybob]

Ahhhhh...
But can you put it back together?... :p

Prolly not...

Never seen brushes with grooves, perhaps they cut through the contact copper on the armature, severing electrical flow. :confused: I thought they are supposed to be smooth.

[retoabcr]

Thank You, saved me $23.00, i appreciated the posting!

[Hoghappy]

Thank You, saved me $23.00, i appreciated the posting!


I don't think I will be buying any more of these either. I was surprised at the quality. Here are some cropped up close shots....it's amazing what you can see through the lens that you can't see with the naked eye.

I may pull the other motor apart tonight and see if I can determine it's failure point. Neither of the motors had more than 20 minutes run time. The last one was a shocker as it didn't get that hot...it didn't even exhibit smoke like the first one I cooked.

Capt. Crash

[Kmot]

Pat, slotted brushes are common.

The failure is clearly due to excessive heat caused by excessive current. You must have overloaded the motor. The magnets can get destroyed by excessive heat, losing their strength.

I have run two Titan 12's in two different boats without issue. In an EP1 outboard on the Pro Fisherman bass boat I ran it a couple dozen times and it is still in excellent condition. In my Harbor Star I am running another, it has over a dozen 30 minute runs so far, no problems. I also tested a Titan 12 with a propeller in my airboat and it did not overheat.

You guys are just hard on motors! :p

[Hoghappy]

Tom...I really just put this out there for you! Now you know what it looks like inside the can. :p

Your right...once again too much voltage and/or too much prop!

The only way I know how to find the best motor/prop package is to torture test it....but some motors can take the abuse...while others lay down and die a little too easily.

Hey my new avitar is a better fit...Crash and Burn! ;)

Capt. Crash

[Kmot]

I've seen a few. :p

[woodybob]

Nice meltdown Tom. :eek:

[mfr02]

Inside the can showing the magnet placement. These are very fragile...they shattered with a light tap on the can with a hammer.
Did they shatter to the hammer, or were they in distress before? A cracked magnet isn't really a magnet any more.

[Hoghappy]

Did they shatter to the hammer, or were they in distress before? A cracked magnet isn't really a magnet any more.

They were fine until I took the can in my palm and hit it on the side with a hammer trying to pop them loose. That's when they shattered. Now I have lots of magnetic particles.

Capt. Crash

[n.h.schmidt]

Hi Capt Crash
The failure point is easy to see. There is only one brush still attached to the copper brush arms. There needs to be two. Cant tell with the second motor though. Just about all the can type motors have grooved brushes. Many boaters put the motor into a container of water and run the motor at a low voltage. This very quickly breaks in the brushes before actually using the motor in a boat. This much increased contact area helps the with the ability to handle the amps the motor will draw. I have done this with nearly all my 600 and 700 type motors. Ned

[Kmot]

Many boaters put the motor into a container of water and run the motor at a low voltage. This very quickly breaks in the brushes before actually using the motor in a boat. Ned
Yup.

[Hoghappy]

Hi Capt Crash
The failure point is easy to see. There is only one brush still attached to the copper brush arms. There needs to be two. Ned

Good eye Ned! I removed the other brush and it is in one of the first pics above but not where it belongs. It is not the culprit. :o

Tom...how many volts are you putting on a 7.2 v motor to break it in like that and for how long?

Capt. Crash

[Kmot]

That is a 12V motor and I ran it at 12V for a few minutes. You do not need to run a motor at low voltage if it is in water. The reason you run a motor at low voltage when breaking in brushes is to avoid sparking and arcing the armature. But if it is in water, it does not spark and arc.

[nick_75au]

One of the motors I tested in the kingfisher hull had been broken in like that. It was the quickest to die, after replacing the motor with a new one it drew a lot less amps compared to the "broken in" motor. The motor was still overloaded and as a result overheated but it didn't fail spectacularly like the first one.

A good way to break in a new motor is to run it for a few minutes on the bench on about 1/3 the rated voltage, say 3 volts for a 7.2volt motor, then clean it out with some sort of motor or commutator cleaner or even blow it out with air to remove the brush particles from the can. Make sure the bushings are lubricated with a drop of light oil, then run it as normal.

The process seats the brushes on the commutator allowing higher current to flow without creating extra heat.

"A round figure for power distribution is 10 amps per mm2 for copper."
This I gathered from some electrical discussion forum, I thought it was interesting, looking at the copper strip holding the brush I estimated that it is around .5mm thick by say 4mm wide giving a current capacity of 20 amps. The brush itself is higher resistance so maybe de rate it to 15 amps. If you added brush-tab cooling you might improve the capacity to 25/30 amps.

I would look at the amps the setup is drawing. I think the current is to high burning up the commutator

Regards
Nick

[Mule One]

:eek: Originally Posted by n.h.schmidt
Many boaters put the motor into a container of water and run the motor at a low voltage. This very quickly breaks in the brushes before actually using the motor in a boat. Ned
=====
:eek: :eek: :eek:
How do you do that without an electrical short?
WoW! ... :eek:

Do you just set it up in the water and then turn it on?

Are you guys pulling my leg?

I am in absolute "shock"...
Richard

PS: Yes, Kmot, I saw your pictures! Still, how do you explain the phenomenom.(sp)

[Rex R]

tap water makes a lousy conducter, electricity follows the path of least resistance, the motor windings are a better conductor...
rest of the answers
yes, no. hth
rex

[Kmot]

It has something to do with the fact our model motors are DC and not AC. If you throw an AC motor into water you can get electrocuted.

[nick_75au]

Hi Kmot and others,
Its irrelevant whether its DC or AC, its voltage and current that's the problem, higher voltage passes through higher resistance easier. If someone were to get in a bath with 110 volts DC in it they would cramp up completely before it probably kills them :eek:.

Not so useless fact, it only takes 30 mA of current running through the body to kill, makes no difference whether its 12 volts or 240 volts, generally the body's resistance is enough that anything below 50 volts wont reach the 30 mA level if you short yourself across it.

Ive been hit by 240 volts AC and 24 volts DC, the 24 volt shock hit me worse because I was bathed in sweat (lowers bodys resistance). I don't recommend it to anyone (ouch).

I wouldn't recommend the water run in, not because of electrocution (unlikely) but waters going where you usually try to avoid water (bearings, windings and ferrous metal parts) , I think the theory of the water was to wash out the brush dirt, Nothing a quick blast with compressed air or spray of motor cleaner cant take care of.

Regards
Nick

[Hoghappy]

I pulled apart the 2nd motor last night. The first one had been run in my bass boat outboard at 8.4v (7 pack) without water cooling (the cooling looked like it was working) and cooked off on the beach after removal from the water. It was smoking and smelled real nice.

The one below was run at 7.2 v (6 pack) in my cracker box boat for a few minutes and never indicated a problem until I went to power up on another test run and had no power.... no smoking, no smell... nothing to indicate it had cooked off.

As you can see from the pics...it shows no signs of failure...very clean and hardly even broken in.

Capt. Crash

I read somewhere that breaking in a motor (water method) can give a 20% performance increase over one that's not broke in properly. Sounds a little out there to me. :rolleyes:

[Stu :)]

Could you do the same liquid run in with a mineral oil?
You could possibly get a two-for-one, run-in and lube ;)

I kinda of agree with Nick on the water idea. Once the motor is out of the water I'd give it a good drenching with alcohol to demoisturize it but the would in turn remove/reduce lubrication... then I'd have to pull the motor apart to re-lube it... unless I'm doing something wrong.

Stu :)

[n.h.schmidt]

Hi
The water break in does work. It has been done for years. The water must wash the com clean and carries away the residue. You can run the same motor for a very long time on the bench (sometimes days ) to get the same degree of brush break in.
When done, dry out the motor your favorite way and oil the bushings. This isnt hard. You don't have to take it apart. There is no danger or shorting with so low a voltage.
I have mostly done this with 700 motors. Their is a great deal of difference in the motor makers idea of brush compounds they use. I have one maker of 700 motor that will break in in about 20 min ,using water. The Graupner 8.4,700sc and SS1 takes hours to break in with water and days to do it dry.
This is all a effort to get at least some contact all the way across the comutator. This will help with the transfer of current.
I run in all my motors in using my 5v tap from a power supply.
n.h.schmidt

[Kmot]

The water break-in works. Afterward you blow it out with compressed air. If you are overly concerned put it in a 200°F oven for an hour.

If the motor comes with ball bearings, they should be the sealed type. Water should not get in. But they could always be flooded with alcohol and then oil afterwards.

Another additional technique that is also used for break-in of motors is to break-in the bushings. This is done by placing some Brasso on the bushings and running the motor dry for awhile. The Brasso is a mild abrasive and polishes the bushing/shaft contact area.

[mfr02]

Fresh water is a poor conductor. Salt water is doom - either by instant electrolytic corrosion or later by just generally eating bits away.
I would avoid letting oil near carbon brushes - it does have a nasty tendency to eat at the structure of the carbon and leave a nasty mess and a bare metal brush.
The one that died without cooking could have been just a proud bit of muck on the comm. The grooves should help prevent that, but its not totally certain. Manually rotating the motor would normally get it back to nice clean bits allowing it to start, the inertia would carry it over the dead bits.