What a beautiful sunday...
 

... i went out on a parking lot to drive with my new built Tamiya "Frog" (Hacker C40l, 10turns, 6cells) and my Supermaxx (BigMaxximum/30cells/ schulze 30.170).

The frog went fine, a nice car! It goes really good for a car that´s been constructed around 20 years ago.

Then i drove three packs with my supermaxx and f*cked up the Bigmaxximum in the last run.

30cells were too much i think. :005:

I can turn the shaft of the pletti without any resistance, it keeps turning for seconds.

What did i destroy?

A burnt through coil?

I will send the motor to plettenberg tomorrow, let them repair it and will sell it on ebay....

I didn´t like it anyway... :017:

Marc.

WOW! 30 cells!?! I was under the impression that the max on them was around 18...Anywho, sounds like the rotor lost its magnetism. If so, you could get Plettenburg to send you a new one and you could replace it. It would be less of a hassle...

Aeeeh, yes, you are right with the 18cells. :002:

I am a tuning freak in real and rc car world. I thought it would be no problem to push a 18cell engine with 30cells. But i am supposedly wrong. :027:

However, why lost the rotor it´s magnetism? Did it went too hot?

How would i observe that a coil burnt through?

Marc.

i think the magnet got loose from the shaft.

Small price to pay for this experiment.

You mean this ironically, don´t you?

To be serious, i am very unhappy with the bigmaxximum getting blown today.

I am dissapointed. You can say that i am a stupid idiot when i run a 18cell spec. engine with 30 cells, but my experience in the world of engines told me that there´s no big problem with overpowering the device IF it is made robust enough!

Some examples: Hacker C50, operated far over specification. No problem.
Hacker C40 - the same.
Lehner 1940 - no problem.

Real world: The engine of my car delivers a power maximum 40% percent OVER the stock specification (bigger k24/26hybrid turbo, bigger+better intercooler, higher boost, only modified camshafts and better output valve shafts). No problem as far as you are requesting the power "wise".

BigMaxx spec: max 18cells, 30cells is something of 60% over specification for short bursts - not running 5 minutes a full throttle.

The BigMaxx looks good but doesn´t fit my definition of a robust engine.

Tell me: Why is it running so unbelievable hot? No brushless motor runs so hot! That´s the reason why there is a cooling fan fitted to the engine...

A lehner 1940 has simply NO NEED for a cooling fan.

Maybe the BigMaxx is overengineered but for my taste there is no need for 4pole brushless.

I can get several wanderer xls for one bigmaxx and the cost for the repair i think will be as high as a new wanderer.

And last but not least: The Plettenberg only runs good with schulze controllers this is not really a highlight.

So one may ask: Why did you buy this engine?

I bought it years ago in a combo with a savage brushless conversion set (schulze 18.97kwf), i would not buy it again.

I didn´t know that the plettenberg only runs adequate with the schulze controller.

The 18.97 had a half life of seconds, the bigMaxximum some months.

Too much money for me.

Marc.

Either the rotor lost its magnetism (the reason I thought this was because it spun freely, like a BL motor should, but unlike the Big Maxximum) or it was what Serum said. The magnet came loose from the rotor shaft. I have had that happen and it wasn't smoothe turning. It was pretty rough to turn it....The rotor would have lost its magnetism simply because over voltage/heat OR the magnet could have come loose from so many RPM's...Either way, take it apart and you can find out...

Marc, don't take it personal.

I took my bigmaxx apart, i know how it's build. It looks okay. but i would never put it on 30 cells.

it doesn't use the big-ass integrated fan for nothing..

I sold the bigmaxximum with the 18.97 and got a 7XL/9920 instead.
Not a bad trade.

Hey, no way i am doing so.

I only wanted to state that i am not a person who is disregarding a good peace of engineering and wants to intentionally destroy it.

To expensive for it.

But as you say - it´s a big ass engine... :-)

Too much bling and not enough bang for the buck.

I will take it apart tomorrow and let you know what´s wrong.

Marc.

Great!

This shows you what to expect;

http://rc.stuurmijmail.nl/Bigmaxximum/index.html

I had a hv that seperated a magnet, it was not smooth either and its similar to the pletty, but not as many plates near the rotor and it also has the hard spots as does the pletty(though not as hard to turn). if the magnet has come loose it must have split for the shaft to roll free. If the magnet did not split and seperate, I'll have to agree with squee on it demagnetizing

... Can someone please explain to me why there are this hard spots on the pletti and why there aren´t any "hard spots" on a hacker or lehner?

Can someone _exactly_ explain the difference between the 2 and 4 pole engines? Or is there a website where it is explained in detail?

I only found this:

http://www.servomag.com/flash/4-pole/smi-motor007.htm

EDIT: I just saw the "Click here for written explanation" link on the page...

What about the burnt through coil?

If i turn the shaft i induce a flux within the coils - if one or more coils are burnt through there will be no flux and no hard spots ???

Is this totally nonsense?

If i pull the trigger the big maxx will turn slowly but you can easily hold the shaft with your fingers. Not enough power to turn.

Will shortly heating up the engine really demagnetize such strong magnets?

Marc.

It's quite possible if it gets hot enough...

The Novaks and the Pletty's have their windings on an iron core (like an armature turned inside out), where others have the windings pressed in the can without the cores. where the iron cores come close to the rotor, it will attract the magnet and will want to stay when you turn, that's where the hard spot occurs.

The general consensus here is you never go beyond 200 degrees or massive demagnetizing will occur, Maybe not in a single run, but over time the magnets life will shorten. It's kind of like Lipo's, you can charge at 2 and maybe 3c and discharge at 20c constant, but due to their nature, it might shorten their life if taken to their max over a set time