Anyone into R/C?

Hey guys. I just started messing with my axial wraith. I bought it used and all the batteries are 3 cell lipos. I have run most of the axial engines from the 20T to the 55T and I eventually burn them out. I like to go slow and crawl but I also like to go fast. Ive heard the brushed are better at crawling which is probably what I prefer. Should I just switch to 2cell batteries and run the 55T and eventually pick up a car for speed with a brushless and then run the 3 cells in that? Thanks for any advise. Im new to all this

 

What kv rating for a good mix of slow and go?

 

Any motor will burn out if you overheat it. Brushed motors will wear out over time, but if you're burning them up, it probably has to do with gearing and cooling. The Wraith doesn't have much room under the body for a fan, but you could get creative and point a motor fan at the brushed motors and it should help.

If you want to go brushless, you'd also need a brushless ESC, the stock ESC is for brushed motors only.

The number of Lipo cells (2S, 3S) basically determines the top speed at which the motor will turn. Motors are rated in kVs, meaning 1000 rotations per volt. A 3S pack has more volts than a 2S pack, so your motor will be spinning faster at the upper range. ESCs have volt ratings and so will state if they're 3S capable or not. If your 3S packs are in good shape, I'd keep those and either be gentler on the throttle, re-gear, or find a way to cool your motors. If you want to switch to brushless, same recommendations would apply (gearing, cooling, temperature monitoring).

 

I'd go with the 3100kV for the Twin Hammers, then you can decide if you want to run it on 2S or 3S. Start with 2S and see how it feels, 3S will give you more torque at the bottom and also higher revs at the top. I see the 2300kV and below motors as scaling/crawling motors more fitted for an SCX-10, but that's just me.

 

Can a lower kv be used with a larger pinion to get the same effect? Just exploring possibilities

 

Thanks for the advise. Ill do some research but it sounds like I just need to go slower even though going fast is so much fun.

 

Novak speed controls are old designed but are built very strong. I have plugged a few in backwards and they just get really hot really fast after the plug sparks. They continued working for years.

I plugged a Tekin RS in backwards and it let out the magic smoke and had to be replaced by Tekin. But the Tekin has current design and software to make it a whole lot faster than any Novak speed control

 

Yes, but you have to be careful with motor temperatures. Also, motors have a "sweet spot" for operating temperature and efficiency, so once you move outside of those you'll be fighting with both. But the same can happen if you take a 3100kV motor and put a smaller pinion on it. You may go "slower" but the motor will be spinning fast(er) more often, which can also lead to efficiency and heat issues.

You could get the 2300kV and be happy, I don't know how you drive your Twin Hammers. I've seen it driven aggressively in various YouTube videos and feel the 3100kV would be a good fit.

 

Never seen a issue with a 300k motor getting hot by useing a smaller pinion.. it's usually loads that causes heat

 

Makes sense of course.
I don't run it in full on basher mode. I'm looking for a nice range of crawl, but not necessarily full on rock crawler slow, with enough speed to require a bit of throttle back before flipping it in a turn.

It currently has a 2300KV brushless, non sensored setup, with a 21t pinion on 2s. The 21T is the smallest I can go, I have no more room for tooth mesh. 28T is the recommended size. I have all the sizes in between too to experiment with. The current setup barely produces any measurable heat after a 15 minute run, tearing up and down the street.

The high end is about right for me, the low end is close, has some cogging when trying to get over obstacles even in low range. I'm thinking the main problem is clearly not being sensored. Would like enough leeway to have some choices for pinion sizes to dial it in. The 2300 size sensored might be what I'm looking for with a slightly larger pinion?
Or can the 3100 be ran with a larger pinion and still be dialed down (programmed) for slow speed..
I know, lot's of noob questions.

I'm seeing these brushless crawler motors branded as 13.5, 19.5, 21.5, etc... From my limited understanding in the brushless world the higher number means slower rpm? Is that correct?

 

The cogging you're seeing at crawling speeds is definitely caused by a sensorless setup, you want sensored brushless for racing, crawling, etc. If you're happy with the 2300kV speeds right now, then you could be right that the 2300kV Roc is the right motor for you. It'll still be plenty fast, especially if you run it on a 3S.

A 3100 Roc has very good low speed torque and resolution, so basically you'd control it with the throttle. You can always reduce your throttle dual rate (don't use expo), which would give you less top speed but more throttle movement over the speed range that remains (if that makes sense).

The brushless motors like 13.5 and 21.5 refer to the number of turns of wire in the stator and actually can be measured in kV as well, it's just that kV ratings vary from manufacturer to manufacturer so "turns" is the formal term used to talk about motor speed ratings. A 21.5 is slower than a 13.5, so the 21.5 will have a lower kV rating.

 

I'll get a little video up here in a bit, let you guys critique my lack of driving skills and all that. And maybe help me nail down this seriously tough life decision.

 

Look at some Holmes Hobbies motors for quality.

 

Mr. Holmes builds quality motors, but his customer support sucks. I can't recommend supporting him, unfortunately, even though I still run a HH motor.

 

https://www.youtube.com/watch?v=OsIkyocmVP0&feature=youtube

 

Oh yeah? Any time I have asked him questions over on RC Crawler I have gotten pretty quick responses. Granted that is just product questions/advice and not product returns or anything.

 

Yeah, sadly he sent me a faulty ESC and after I sent it back for RMA, I couldn't get a real hold of him or get accurate status updates for over a month. Took a chunk of the summer away for my new Wraith.

 

Sensorless is garbage

 

Well, it depends on the application. For instance, I have a Hobbywing sensorless system in my customized Stampede (my only basher) and it does very well. It's a waterproof ESC and a sealed motor (so I have to watch the temperatures) and thus perfect for a bashing application. Sensor wires and bashing don't really mix in my opinion. But yeah, for anything needing precision, a good sensored setup is a must.

 

after researching sensored brushless until my eyeballs bled, I've decided to increase the size of the spur gear.

Waterproof is kind of important to me as I run in the snow. I'm sure a sensored system could be waterproofed just fine. but damn they are expensive to get a good setup. Seems overkill for a guy just screwing around, but will prolly happen eventually anyway. Maybe even today. Both my lhs carry Tekin and Novak products.

My video actually showed me a thing or two...
My skills do not warrant added speed.
The cogging /low speed issue might be alleviated with lower gearing.
So Losi makes spurs that bolt right on, the TH has 78t stock and can go as high as 90t.
This may open up some more gearing/performance options.
I can always drop a 3s pack in it too if I need to spin the rubber off the wheels.
So I'll try this first as it's cheap and easy and a kevlar spur gear isn't a bad thing to have.