Which is better? (mega/feigao) - Page 5 - RC-Monster Forums

speed demon · 05.02.2008, 10:42 PM

Holy crap I'm a moron. It's all my fault for it not working right. When I first turned it on I had to do the whole radio thing. After I did that the forward was reverse and visa versa. Not really thinking too much about it I just flipped the channel switch on the radio. During the first run with the guys I didn't use my brakes but later(during lunch) I was out back bashing around the RR tracks and noticed that when I hit the brakes that it goes into reverse. That got me thinking then it hit me I had the wires to my motor backwards. I set it up to have 75% brakes so there for I was only running 75% forward with the wires backwards. Man I feel stupid.

There was a spare fan at work the right size so I'm using it but it is made for 12V so it doesn't push much air but it mounted perfectly so at least I know the size I need.

Thanks for all the help...much appreciated.

Last questions. If I do get dirt and stuff into the motor can I simply use cleaner that's made for the brushed motors? Same process?

Revracer · 05.02.2008, 11:19 PM

the mega is sick! i love mine. run it in a revo on 3s geared for only 40. it is crazy strong. loads better then feigao

DrKnow65 · 05.02.2008, 11:35 PM

Don't know about the brushed cleaner? I use a shop vac (never compressed air, it pushes stuff into the bearings). Once in a while take the motor out and make sure it spins free, you can get bad bearings or iron filings stuck on the rotor (like putting a magnet in the sand, you pick up stuff).

You ran it long enough to get new temps yet?

speed demon · 05.02.2008, 11:45 PM

Nope will have them tomorrow. I have a ton of cycles on my lipo and will be getting a new one in the near future. I've had such great luck with the milehighrc pack that I don't want to get anything else but I've be considering a 4S and he doesn't have them in 4000mah. Doing the math the motor is a max rpm of 44k and a 4s will be over that but I've read here before that a motor normally doesn't reach its max rpm becaues of drag and what not. Also the MM has a setting for a 4S lipo cutoff...does that mean it can handle it? I ordered a fan and terminals today so it should be in next week. The fan is 40mm square but that's the fan size that mounted great. It's 5v and pushes 6cfm. Should that be enought to cool it?

DrKnow65 · 05.02.2008, 11:50 PM

Do you have the ubec yet? if so the MM should take the 4S just fine, lots of guys running that way. You HAVE to have the ubec for 4S or else the internal bec will get to hot.

6cfm is very respectable, again though you'll realy have to have the ubec, the wattage the fan pulls will make it even harder on the bec.

speed demon · 05.03.2008, 01:07 AM

No I haven't gotten a ubec yet. If I stay with a 3S would there be any difference in run time or performance if I got one? Or is this more a thing for longevity of speed control? Sorry for all the questions but all these electronics just baffles me. TIG welding and muscle cars is about the extent of my knowledge.

DrKnow65 · 05.03.2008, 09:57 AM

Tig welding (soooo jelous, I know how, but have no access to one now that I live in Colorado :(

The ubec will put out more amps without dropping in voltage like the internal bec, so your servo's and fan will perform better even on 3S. Also the internal bec is set to 5v and the ubec is adjustable (via the caslt link-not the usb cable for your mm- castle link) so you can set it to 6v, or I like 6.2v because when you load it down it sets right a 6v...
So when you see the servo spec's at 5 and 6v you get an idea of the difference in performance. The ubec will help some with the ESC temps even on 3S, and alot more on 4S (BrianG has done some tests on the performance/heat of the internal bec, you can find it if you do some searching of his posts/threads).

Glad you found a problem (with the settings). I'd still highly recoment the taller pinion gears though, you'll notice a big difference, that mega is a torque monster.

BrianG · 05.03.2008, 11:11 AM

Quote:

Originally Posted by DrKnow65

...BrianG has done some tests on the performance/heat of the internal bec, you can find it if you do some searching of his posts/threads...

I just tried to find it but no luck. To summarize; even on 3s the internal BEC heated up quite a bit with a very small load (less than 0.5A). On 2s it was fine.

ANY linear BEC has two enemies: high load current and high battery voltage (vs the 5/6v output). An increase in either (or both) of these values results in lots of heat. A 4s setup with a 2A load will generate around 17 watts of wasted power. Not good on such a small circuit. For anything over 2s or 7 cells, use a UBEC.

speed demon · 05.03.2008, 12:36 PM

I finally got another run in and the power was awesome(much better then before). It's harder to control then the vxl and I honestly couldn't even make a full power pass going down the road, it was just floating then a slight wind came and I kept spinning out as I was trying to get full power. The MM shut me down once and the temps were 221, motor was 141 which is higher then before so I might try going back to the 26pin. Over all I'm very pleased and will be even happier when my fan comes in.