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B.RAD

Brushed Vs brushless on lipo

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Hi wise TC folk

This may well be a proper noob question, so please feel free to roll your eyes and mutter "not another one"!  But I would very much appreciate your guidance as this is all new to me.

I've just built a Traxxas Stampede 4x4 and am running a 5000mah 2s lipo pack through the standard XL5 ESC and Titan 12T brushed motor. I was expecting it to be quick, certainly quicker than my Mad Bull on DT03 buggy wheels on a Sport Tuned motor and a 5000mah NiMH battery, because of the lipo boost and the lower turn motor. But it's not. I would say it's close, but definitely slower than the Mad Bull. This was quite a disappointment. Don't get me wrong, it's a lot of fun, it handles really nicely and jumps very well, I was just expecting it to be a proper ripper but it is slow in comparison to the MB.

Is it slower because it's 4wd and there's much more power loss through the double diffs and slipper clutch etc? It's also noticeably heavier so that may have something to do with it. Have I done something wrong with the diff or slipper clutch build that's robbing speed?

I have a Hobbywing EZRUN Combo MAX10 3652SL 4000KV Brushless Motor and 60a ESC ready to go in, will this make a significant difference or will I find it disappointing again? I'm expecting a sudden transformation of speed, akin to bolting on a turbo, is that setting my expectations too high?

Should I go for 3s? What level of difference would this make?

Is the comparison of a 2s 5000mah lipo and a 5000mah NiMH pretty similar? Again I have no prior experience here so was expecting lipo to be a bit like a nitrous shot, so have I just come into this with the wrong expectations? Or would it be slower again on NiMH?

Thanks in advance for your replies!

B

 

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I think with the Pede being 4wd and heavier contributes the most to the difference.  Your build is most likely spot on.  Your Madbull has much less rotational mass to deal with.  Gearing could have some to do with it also.  Short answer... yes that brushless system will be a noticeable difference!  I think every ESC I have is Hobbywing,  I really like both brushed and BL ESC's of theirs.  Do the BL upgrade but stay on 2s.  If it is still not enough, go 3s.  Hope you have a wheelie bar!  And yes, I personally think your expectations were off between lipo and nimh batteries.  In the case of batteries, they only supply the power when requested.  They do not push power into the system.  So, if both variants of batteries provide more voltage, amperage, wattage, whateverage your system is calling for, you will not see a difference.

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Also bear in mind that the Titan is a 550 motor, which rev lower. So although a 12t 540 would rev very high, a 12t 550 is not any higher in rpm than the 27t Tamiya silver can motor.

But the Titan is more powerful. Which leads onto the differences in drivetrain and weight. And also to the same conclusion that if you want much higher performance, you'll have to go brushless!

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Thanks @sosidge, that's really useful and something I wasn't aware of. It just feels like the car is holding itself back - it gets up to speed quickly, but then just doesn't gain any more speed. I'd liken it to when a car runs out of cam - everything else is ready to go faster, but the cam just stops it making any more power.  There's no way this would get close to 30mph!!

Good job I have that brushless set up in stock then eh?!

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What you are describing is a function of gearing.  If you play with spur and pinion gears, you can make your brushed setup much faster on the top speed.  But you will probably sacrifice some acceleration.  I still say throw that brushless system in there and have fun!

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With only a 60a esc, I'd say you're close to the limit of the esc running 3s /4000kv, so if you've pinions/gear options, go for lower gearing, especially in a heavy car.

 

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3 hours ago, Wooders28 said:

With only a 60a esc, I'd say you're close to the limit of the esc running 3s /4000kv, so if you've pinions/gear options, go for lower gearing, especially in a heavy car.

 

Thanks - I do have a bit of an update here. I fitted the 4000kv motor and ESC combo on the standard 9t pinion and ran the truck on 2s lipo. It was quicker again, but not ballistic. It's like 5-10% quicker each stage (NiMH to lipo, brushed to brushless). Given I've run that same motor and ESC combo in my DT03 buggy and it was absolutely bonkers fast, it was a massive disappointment for it to be only marginally quicker. On the positive side, it was a bit faster, and still very driveable and enjoyable to run. 

Now I'm on a sort of quest to find the point at which the car is super fast and still driveable. So, I've bought a 15t pinion and installed that. Might be too much of a leap up, so I've bought a cheap goolRC 3800kv motor and ESC combo and put that in so if the motor fries, I won't be too bothered.  Will update on my main thread.

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1 hour ago, Fabia130vRS said:

You need a pinion over 20T 

Not possible. 17t is the max, and that is apparently good for well over 60mph so defo overkill for me!

I think 13t would be the ideal balance but I'll experiment with the 15t and see how it goes.

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6 hours ago, B.RAD said:

I've bought a cheap goolRC 3800kv motor and ESC combo

If you need torque, I don't rate the Goolrc, or anything cheap unfortunately.

I found the Castle 3800kv, night and day quicker and more powerful, than the Goolrc 4300kv, even though the specs say otherwise (picked the Castle combo off eBay for around £60) , I ran a Castle 5700kv on 3s in a Dark Impact for years, and it was awesome (now a 7700kv speed run car) , I was £90 for the Castle Mamba max esc and motor off eBay, but that esc is 6s capable, and ran that combo on 5s, as the castle motors are rated to 100k rpm!! 

 

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2 minutes ago, Wooders28 said:

If you need torque, I don't rate the Goolrc, or anything cheap unfortunately.

I found the Castle 3800kv, night and day quicker and more powerful, than the Goolrc 4300kv, even though the specs say otherwise (picked the Castle combo off eBay for around £60) , I ran a Castle 5700kv on 3s in a Dark Impact for years, and it was awesome (now a 7700kv speed run car) , I was £90 for the Castle Mamba max esc and motor off eBay, but that esc is 6s capable, and ran that combo on 5s, as the castle motors are rated to 100k rpm!! 

 

Awesome, great advice, thank you!! I know the goolRC stuff isn't going to be anywhere near as good as decent stuff (you get what you pay for!) but in this case it's worth it for the experiment and to see if I like the Stampede with more power or not. It's one of those weird situations where it might be just perfect on its standard brushed set up, and anything more ruins it, but part of the fun is trying stuff and finding out for myself! So easy to revert back to standard and just change the pinion if needs be 😊 

If it copes alright with this and I think it can take more power, I will check out the Castle combos 👍

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Even the Hobbywing stuff is decent quality but unfortunately has significantly climbed in price, since it was first released..

But the one castle motor I had destroyed everything I used it in . Lol

Got rid of the castle motor in the end because it was just savage.. lol

Edit 2add, my driving probably didn't help but those Castle motors have power..

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