Quark 125b thermaling

[Batfish]

I read your posts and the replies at the other forum, then put up my own. "tripthreat" appears to be "Frank", an employee of Quark. I was personally disappointed to read this part of one of his replies, so I countered with my real-life experience.


Quote:
Originally Posted by tripthreat
I would love to be able to run a 15 minute main, but right now, there are no controllers that will allow you to do this competitively against Nitro Cars. That is not pesimistic, nor defeatist, it is the truth. If it was defeatist, I would not be looking forward to when it will be possible, and our company would never strive to make a better controller, but such projects and aspirations are in stages of development.


I'd just like to add here that the first statement in this comment is incorrect. I run a Lehner 1940 motor on a BK 9920 controller with 4s2p 6400mah in a converted OFNA MBX 1/8th scale buggy, geared 14/51, and I can run for over 25 minutes without either motor or controller going over 120F in ambient temperatures of 95F.
The big difference is the motor. The Lehner 1940 is considerably more efficient than the Feigao or BK "L" or "XL" cans. Of course, there is a $200 difference in the price, but that makes all the difference in the performance.
If I used an L or XL can in my buggy, both the motor and controller would overheat inside of 7 minutes.
I'd be pretty confident that the Quark could do the same with a higher-quality motor attached to it.

Joe

[smhertzog]

So I have to buy a new motor?

[Batfish]

Originally Posted by smhertzog

So I have to buy a new motor? Before I bought this combo 7xl & quark 125b I specificly asked if I would have thermal issues. I stated I wanted to be able to run out a full charge on my Orion 4800's. I would have dished out the extra $ for the lehner if it would have been given it as an option. I bought a pair of 7xls and a pair of quarks for my two trucks. Now I'm not sure what to do.:032: My wife will kill me if I buy a pair of lehners and have almost $200 worth of 7xl's collecting dust.

Are you racing, or bashing? The L and XL motors can handle some pretty hard bashing with no problems. The rigors of racing, however, will take their toll on the L and XL motors pretty quickly.
Many people who bash, even running their vehicles at high speeds up and down the street, and don't race them - they unfortunately don't quite get the difference. I do both; bashing and racing (mostly racing), so I have first-hand experience with the differences and how they affect the electronics we use.
When you bash the vehicle comes to a complete stop many times during the session. For example, if you're hitting a jump in your back yard, you'll line the vehicle up then hit the throttle. The vehicle gets some air, lands, you check out the landing, then you line it back up again. Chances are you just stopped twice within a 15 second period, giving the electronics a chance to rest. The same holds true for high-speed runs - you'll typically stop at both ends of the run.
When you race, you do not let up from the throttle for a solid 5 minutes (or more), so the electronics never get the rest they get during bashing. Most off-road racing consists of multiple jumps and many turns. At each of the points on the track you're doing everything you can to keep your vehicle moving forward as fast as you can control it. If you're using the motor as a brake, you're probably also pushing the brakes hard up to 50 or more times during a 5-minute race. Braking is VERY hard on the controller because the motor is usually trying to halt the progress of an 8-15lb vehicle from whatever speed it was running, then you're immediately back on the throttle again to make it out of the turn and line up for the next jump, etc... The same thing does not happen during typical bashing.

If you bought your electronics to put in bashing vehicles, there's a very high probability that what you bought should be just fine.
If you bought your electronics to put in vehicles for racing (especially to race for long periods like 15+ minutes with nitros), you almost definitely need a higher-efficiency motor.

Additionally, you can look into getting the software updated on your MGM if the only problem you have with that is reverse. Mike has told me that MGM now has the ability to disable reverse, but it requires an upgrade that MGM must perform. I have both an MGM 12012 and an MGM 8012 being upgraded now and I'm hoping to disable reverse on both when I get them back.