1/8 scale buggy conversion - help please!

[padailey]

ok so in the Novak sensored world of motors ... if you thermal the rotors tend to be damaged and will thermal easier the next time. The sintered rotors reduce the heat and are much more difficult to thermal... however the rotors will not be damaged until 250 degrees (or so I've heard) so a thermal does not degraded the performance of the motor. So with the type of setup (MM/Feigao) what is thermalling normally... speed control or motor? And does thermalling the motor damage the rotor at all?

[Serum]

A Neodymium magnet starts loosing its magnetic force at 80 degree C.

completely at 312 degree C; novak/feigao/lehner/wanderer/plettenberg/neu all use the Neodymium magnets.

Sintered magnets or segmented magnets are better suited for partial loads. this has something to do with eddy currents. the segments simple respond better to the signal than a larger lump. (it's like with transformers, the thinner the E's and I's are in the transformer, the higher frequency it is capable of handling. (the more efficient the transformer becomes at higher frequencies)

[Dafni]

Originally Posted by Serum

A Neodymium magnet starts loosing its magnetic force at 80 degree C.

completely at 312 degree C

Might be true for one grade of Nd magnets, but there many different compositions and grades, optimized for different applications.
Our motors use what they call UHT (ultra high temp) grade Nd magnets, but even there you find differences.

And BTW, sintering is a way of manufacturing solid bodies. Basically it means "backing a powder together", or something like that.

DAF

[Serum]

Yeah, it seems to me that all of these rare earth magnets are sintered? (since they don't find them in the perfect round shapes)

i thought you said the magnets lost their magnetic forces at 110 degree?

[BrianG]

Maybe that's 100*C? 110*C is 230*F...

[Serum]

yes, C for sure, but that's what I am talking about too.

Any of you guys running 3s in your 1/8th conversions?

[BrianG]

I don't think you'll find too many running that config. You'd have to have higher current (about 25% more) at 3s than you would at 4s for the same power.

[padailey]

Well got my motor and such from Mike today... now just gotta mount everything and wire it up.... should be up and running soon!! I'll get some pics when I'm done. Thanks guys for the help!!

[padailey]

Ok I hit a couple snags... first I need to rethink the placement of everything. I'm just a little short on space with my original plan. I'll get that figured out. Then my center diff is binding up pretty bad. Need to get to the LHS and get another gasket.

Then the problem I don't know what to do with. My intention was to get a Wanderer 9XL but when I ordered I didn't specify that so I have a Feigao 9XL. Don't really care just stating it so you know what I have. I hooked it up to my MM outside the car. So its 6V receiver pack, spektrum receiver, servo, MM, 9XL, (2) 7.2 IB 3800's in series.....once through the initial setup I start to run the motor. I don't know what cogging feels like but the initial tugs on the throttle there is a definite stutter in the motor (every time from neutral) . This is under no load on the motor. This can't be right can it? Is there something in the MM setup that could be causing this?

[padailey]

Alright I've found a couple threads talking about this issue but not always solid results. What worries me so much is I haven't even tried to move the buggy yet!

The connectors I got are very small... small enough that the female plugs slide inside the orginal 4mm MM ones. So I'll try to direct solder the motor wires. Dean's are on the battery wires so I'm not too concerned there.

Next I'll try playing with the timing and punch control on the MM.

Any other suggestions?

[BrianG]

If the CD is binding, a simple gasket should solve that easily enough. However, a binding CD would effectively lock it, but won't cause the cogging issues. How free is the driveline without the motor hooked up? I assume the mesh is set perfectly (not too tight)?

Direct soldering the wires is always the best solution, but makes taking the motor and/or ESC out for maintenance a PITA. Unless the connectors were really loose or highly inadequate, you shouldn't notice much difference. The connectors that come with the MM are 4mm - not the absolute best, but should be ok.

I'd check MM settings like start power (set to default "med"), lipo cutoff (should be disabled with using NiXX), and torque limiting (I'd set it to 0%).

[padailey]

I've been wondering what people mean when they say gasket for a Hyper 7/8. Is it the thin red rubber ring that seals it or the blue gaskets for a Jammin or 9.5. I was going to try the rubber seal with the blue gasket, but I have both so I can try it different ways. As far as the drive train goes I can't drive the car at all because the spur hit the chassis just slightly. I'm hoping the gasket is enough that it will fit or I'll have to enlarge the hole in the chassis slightly.

My cogging problem is with everything outside the car. It is very noticeable because I am holding the motor. It seems really weird that it should be as fast as everyone says it will be because my Novak 13.5 feels like more power than the Feigao (except when cogging). Weird.... Anyhow I'm wondering if it will even happen as much on the track. It's only when the rotor is stopped that it does it... I have the drag brake set on the MM so when I let off the throttle the motor stops (with no load), however on the track if I don't come to a complete stop the motor should still be spinning some so I probably won't have the cogging (at least I hope). Between that and some settings on the speed control I hope it goes away.

I'm unclear about something. First you say that the connectors that you got are smaller than the connectors on the MM, but you also said that you were running the setup and then you make reference to hardwiring.

How did you make the connections to get it running when you saw the cogging? A bad connection like a loose on or a bad solder joint will definitely introduce some pretty horrible cogging.

A brushless motor will pull as many amps as it needs to meet the demands that you put on it. Although I may be wrong, for this reason, I run my MMs at the highest start power setting with the timing on the lowest setting. My systems run very well like this and as cool as a Feigao can run.

I would look to the connections first and if you haven't hardwired yet, go ahead and do that, unless you have some good connectors. I'd say that the 4mm connectors and just barely adequate for a 1/8 scale application.

[padailey]

Originally Posted by AAngel

I'm unclear about something. First you say that the connectors that you got are smaller than the connectors on the MM, but you also said that you were running the setup and then you make reference to hardwiring.

How did you make the connections to get it running when you saw the cogging? A bad connection like a loose on or a bad solder joint will definitely introduce some pretty horrible cogging.

Sorry I wasn't clear.... I ordered the motor expecting a Wanderer (because that was the picture) so I ordered some of the 5.5 connectors. When I got the package it was a Feigao and a bunch of connectors but they are very small (I think 2.5mm). They came from Mike so I'm assuming they are quality just seemed a little small. So I hooked everything together using the new connectors I received removing the 4mm original on the MM. I know people mentioned hard wiring or using larger connectors that's why I'm thinking about hard-wiring the MM to motor. I also just changed the settings on the MM so I'll see how that goes.