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Old 04-21-2008, 10:10 PM   #6091
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Well, there are a number of things that contribute to heating...

The current being pulled in these ESCs/ motors is pretty impressive... and there are switching losses associated with turning on and off the transistors that are just very difficult to get rid of completely.

Also remember that the transistors are only part of the power train... those wires that you have soldered between the ESC and the motor are another source of resistance/voltage loss.



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Originally Posted by deskwarmer View Post
Hey Steve,

How come ESC's get so hot even though the on resistance of the mosfets are in the milliohms? I think I read something a long time ago that its because the fets are spending too much time in the triode region (is that the right word?) and aren't being switched fast enough. I'm not sure though. Don't hold back on the technical explanation.

-Jon
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Old 04-21-2008, 10:14 PM   #6092
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awesome !!! next page, I got tired of seeing that offroad car
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Old 04-21-2008, 10:16 PM   #6093
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Thugs... all that I can think of is that with the better mechanical advantage you had on the tires with the spur/pinion ratio you had to run

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Hey Steve,
I ran a 17.5 w/4cell SS GTB in my 12th scale all this winter and am puzzled by something. At the beginning of the winter I was truing my tires way down to reduce rotating mass, but I couldn't get the gearing right with the pins I had so in final desperation I ran the biggest pin smallest spur and full height tires. This finally made the car go fast. Once I had found that magic rollout I figured I'd get back down to smaller tires again. What I found was with an identical rollout, the car was faster and came out of the corners harder with full height tires. This has stumped me and I'm really at a loss to explain it. It feels like I'm looking at some kind or perpetual motion machine or something. Can you 'splain it to me please
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Old 04-21-2008, 10:16 PM   #6094
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No idea on that one... looks alot like the other's out there...

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Originally Posted by syndr0me View Post
Any guess on who makes this motor? I don't think it's a Feigao. It might be the most blatant Novak copy yet.

http://cgi.ebay.com/Team-SPEED-Tamiy...742.m153.l1262
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Old 04-21-2008, 10:18 PM   #6095
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It really depends on the type of motor... I think the CO27s you run up around there... I want to say some guys run closer to 6.3 or 6.5 though.



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Steve
Im just starting to race 27t stock class with my xray t1fk04 and what would be a good ratio as a starting point? im running 6.09 as my final gear ratio with a 93 spur to a 27 pinion. The track is short and tight with one main straight
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Old 04-21-2008, 10:21 PM   #6096
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Thanks Steve.

After the thermal issue I'll work on installing the new LiPO pack. I just couldn't make an order for one part. After that I heading over to Lowes and dropping off some NiMH for recycling (Earthday) and I'll work on my corner speed I guess those 3.5's have some getty up and then some.
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Old 04-22-2008, 11:01 AM   #6097
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I was preparing the car for a lipo pack by removing the bulkheads and milling off the nubs for sub-c cells and noticed my motor was scratchy when I turned it.

So took the motor, popped the endbell off and boy I had a mess. That sintered rotor looked like beach sand.

I didn't realize it was possible to have a semi-functional motor when the rotor is in a million pieces. The air flow issue may have caused heat in the GTB buy my reduction to gearing to 12:1 may have killed the rotor. I didn't free rev the motor but it doesn't mean it hadn't been either. The motor was one of those slightly used ones on ebay. Are the newer rotors better(not different)? Because this was one of the early 3.5 motors.
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Old 04-22-2008, 02:06 PM   #6098
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There have been some small running changes that should help prevent rotors exploding like that...but unfortunately when you're pushing things to the limit sometimes things just let go.

The replacement rotors that we sell will be fine for your motor. Either a 12.3 or a 13.0 mm will be good!

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Originally Posted by trailranger View Post
I was preparing the car for a lipo pack by removing the bulkheads and milling off the nubs for sub-c cells and noticed my motor was scratchy when I turned it.

So took the motor, popped the endbell off and boy I had a mess. That sintered rotor looked like beach sand.

I didn't realize it was possible to have a semi-functional motor when the rotor is in a million pieces. The air flow issue may have caused heat in the GTB buy my reduction to gearing to 12:1 may have killed the rotor. I didn't free rev the motor but it doesn't mean it hadn't been either. The motor was one of those slightly used ones on ebay. Are the newer rotors better(not different)? Because this was one of the early 3.5 motors.
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Old 04-22-2008, 08:22 PM   #6099
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Thanks steve im running an epic 27t motor
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Old 04-23-2008, 01:05 AM   #6100
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Steve,

I know the trend with 1/18 cars is to go as fast as possible, but for those of us using the car for practice in a confined space, that's not terribly realistic. Will the Mongoose motors (13.5) be reasonable in a smaller space, perhaps with 4 cells? Will Novak look into creating higher turn motors? For me personally, I'll be using the car on a 12x24' track with 36" lanes. I tried using a smaller car (1/24), but just couldn't get it to be durable or handle consistently, so I'm hoping 1/18 will still be usable in the space.
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Old 04-23-2008, 02:19 AM   #6101
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Default Charging in the Smart Tray

Hi Steve. I want to know if one can charge a 6 cell pack while in the Smart tray? The theory, discharge pack till cutoff, stop discharge, connect charger terminals and begin charging with pack still in tray.

Why I am asking is I notice that on the + an - terminals they have spade connectors, and I am assuming that they are there for charger leads.

Thanks!
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Old 04-23-2008, 06:32 AM   #6102
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Steve, don't know if you have been asked, and this may have already been confirmed, but is Novak producing the new Losi Xcelorin Sensored Brushless Motors and ESC's???

Or does Losi just get their parts from the same supplier as Novak? The ESC and motor look very very similar, just minor differences.
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Old 04-23-2008, 08:59 AM   #6103
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Syndrome,

Well, it's impossible to say exactly how your car will react w/o knowing how it runs or what exactly your surface is like, but I would tend to think that the 13.5 should be slow enough to be reasonable on a small track such as yours.

We have discussed winding slower motors and I believe that we will be working on these after we start shipping the three announced systems.

Quote:
Originally Posted by syndr0me View Post
Steve,

I know the trend with 1/18 cars is to go as fast as possible, but for those of us using the car for practice in a confined space, that's not terribly realistic. Will the Mongoose motors (13.5) be reasonable in a smaller space, perhaps with 4 cells? Will Novak look into creating higher turn motors? For me personally, I'll be using the car on a 12x24' track with 36" lanes. I tried using a smaller car (1/24), but just couldn't get it to be durable or handle consistently, so I'm hoping 1/18 will still be usable in the space.
Howard,

I would not recommend charging your pack while it is in the smart tray.

The two blade connectors are there so that you could discharge an entire stick type pack down to whatever desired cut-off you would like.

Quote:
Originally Posted by howard1 View Post
Hi Steve. I want to know if one can charge a 6 cell pack while in the Smart tray? The theory, discharge pack till cutoff, stop discharge, connect charger terminals and begin charging with pack still in tray.

Why I am asking is I notice that on the + an - terminals they have spade connectors, and I am assuming that they are there for charger leads.

Thanks!
KN,

No, we are not producing the new Losi Xcelorin motors or ESCs.

I'm not sure where they are getting their parts supplied... but yes, their system looks very similar to ours... so much for putting in some effort to come up with your own design, eh?

Quote:
Originally Posted by kn7671 View Post
Steve, don't know if you have been asked, and this may have already been confirmed, but is Novak producing the new Losi Xcelorin Sensored Brushless Motors and ESC's???

Or does Losi just get their parts from the same supplier as Novak? The ESC and motor look very very similar, just minor differences.
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Old 04-23-2008, 09:31 AM   #6104
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Quote:
Originally Posted by Steve Weiss View Post
Well, it's impossible to say exactly how your car will react w/o knowing how it runs or what exactly your surface is like, but I would tend to think that the 13.5 should be slow enough to be reasonable on a small track such as yours.

We have discussed winding slower motors and I believe that we will be working on these after we start shipping the three announced systems.
Thanks, I'll pick one up when they're ready and give the 13.5 a try. I'm hoping to simulate the feel of a 1/10 sedan as much as possible. My current surface is a poor man's RCP, which is actually really grippy, at least with rubber tires. I can get a small roll of Ozite for like $250 shipped, so I might do that if the space works out well with this car. I appreciate the prompt reply.
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Old 04-23-2008, 04:15 PM   #6105
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Quote:
Originally Posted by Steve Weiss View Post
Thugs... all that I can think of is that with the better mechanical advantage you had on the tires with the spur/pinion ratio you had to run
Steve,
First off I think I forgot to mention in my first post that YOU ARE THE MAN for coming in here and answering like EVERY post. Seriously dude you rock! Thanks. As to my first post I didn't quite understand your answer. Are you saying that I have a better mechanical advantage turning larger tires with the exact same rollout? I'm not the only one to notice this, at our track any way. We see it in the way we drive as well. If we try to roll corners and carry speed the car comes out sluggish and takes longer to wind out than if we drive point and shoot. Like I said it's really weird and completely contrary to what we know of brushed and quite frankly physics.

Thanks again.
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