Power Consumption Questions

[BQuicksilver]

Hi all, I'm dusting off the old RC cars and very curious about going brushless, but need some advice.

My uses:

I would describe my expected use as 50%bash/50% practice at track and racing for fun. I'm not interested in getting consumed with high $$ bateries and some of the serious racing craziness. I've already done that with full size cars and want to keep this as a cheap hobby.

I've decided to buy a Tamiya Dark Impact, which seems appropriate for the stated use above. I have a close friend who plans to also go the same route so that we can compete a little.

My current setup is an old Kyosho Optima Mid and 12T Twisters wet mag motor. I have 2 dreadnaut 3000 packs from Hobbytown and a 3300 from radio shack. The batteries are new. I get about 12 minutes/pack with that setup.

My goals:

I would like to find a motor setup that would net me 6-7 minutes of runtime on my current batteries, but have much more acceleration, as I just don't have enough punch to make the triple at our local track (Planet RC - Indy), and have to get too much of a run to hit doubles as well. I was running my mid size pinion when having issues, but I don't think going to a smaller one will fix things enough with the Optima. It's not too fun knowing that it's your rig holding you back on the jumps no matter how well you drive. I'd like to make missed jumps MY fault again with more power.

My questions:

1) How much runtime would I be looking at with a brushless setup on the batteries mentioned above. I've read a million times "gp3300 is the bare minimum" (so please don't give that advice), but would like to quantify things if possible. Knowing I get 12min from a 12T brush setup hopefully will help. I'm looking for max power for ~7 minutes from my batteries.

2) I've read a lot of comparisons here like "10T brush is equal to 5T brushless"... Outside of less maint, what would brushless give you over a supposed equal brush setup? In other words, how do "even" brush vs brushless compare in top end, low end punch, and MOST IMPORTANT battery runtime? Keep in mind my 12T is ancient, so I'm not sure how that affects battery use and power.

3) Does the Dark Impact sound like an appropriate car for our use? any issues with using a brushless on it?

Thanks In Advance!

[Rtsbasic]

3) The Dark Impact looks like a pretty tidy car to throw a brushless setup in, should handle the power okay. I'm certain a couple of people on these boards run brushless in one.

2) Comparing for example a Feigao 380C-9T to a brushed Orion V2 12x1 motor, where overall power output is fairly similar, the brushless motor will have considerably more low end torque while reaching about the same speed. Runtime is significantly increased, brushless motors are a good bit more efficient than brushed motors. Where I used to get approx 6-7 mins driving in my T3 with the 12x1, I would easily get 10 mins with the 380C 9T. Actual runtime depends a lot on your driving style, rolling resistance, quality of batteries etc but it *will* be higher.

1) If you can get 12 mins from your 12t brushed on the GP3300, you should be able to use a much more powerful motor and still hit 7 mins easily.

I'd recommend a Mamba Max 5700 combo for your application. You could go more powerful with the 7700 but it sounds like having a good bit of runtime is important as well (the 7700 would still make the 7 mins though). Plus the 7700 will make your batteries suffer more - the "generic" 3000's you have won't be any worse on the 5700 than they are on your brushed setup (when geared correctly), but you will notice a jump in power when switching to the GP3300 pack. I'm happy with the 7700 in my B3 though, using GP3700 cells.

[tcolesen]

1) Runtime depends on the motor you get. When comparing a brushed 12t to a brushed 20t, the 20t will give more runtime. With brushless, it works the same way.

2) Rts answered it well.

3) The Dark Impact is a great buggy for brushless. I have yet to strip any gears on mine while running the Mamba Max 5700 system on 2s 6400mah and 6000mah Lipo packs.

[BQuicksilver]

Thanks for the great answers!

1) That's good to know I'd run longer brushless. I was under the impression the 3000 packs would just get smoked in a minute or two.

2) I was under the impression that brushless had HUGE current draws and required high-end packs. Was i under that impression simply b/c most all brushless are very low turn motors, and any low turn motor (brushed or brushless) pulls a lot of current? So a 10T brushless would get more runtime, spin up faster, and make more top end than a 10T brushed?

3) Good to hear, the price is definitely right on the DI.

[SS Pede]

Regarding 2) BL motors pull a lot of current because it's a really powerful motor design in general. Really low turn brushless motors tend to pull more current so they're harder on the batteries. Low turn brushed motors pull lots of current too, but its not quite the same as BL motors. A 10T brushed could be faster than a 10T brushless these days. But if you talk about "equivalent" BL vs. brushed motors (ignoring turns for a second), the BL motor will be more efficient. Low end torque is ridiculous as well.

[JeffEmbracedDC]

Bacially what they said.

I would also suggest the Mamba Max 5700 for that car and track. I used to race there when I lived in indy for a few months :) Actually, I bought my gp3300 packs from the guys at planet RC that I currently run with my own mamna max 5700 set up. I haven't yet raced with it and honestly haven't really times my run times, so I can't help much there. If you're worried about run times you could maybe get the 4600 motor and gear up a little bit. That track isn't huge, so the 4600 geared a little tall might be the best choice. Either that, or the 5700 geared a little low. As far as pricing goes, it's about the same price as high-end modified. Let's say you'd pay $60 for a high end mod brushed motor and $150 for a high-end novak esc. Well that's $210. The mamba max systems are $213 from tower hobbies. So it's like the exact same price. I'd say you would have a very nice and fun set up with that car and motor set up. The only thing I would remind you of is that it would be best if your local hobby shop carried tamiya parts. I know P R/C didn't when I raced there, and the hobbytown USA was about 30 minutes away and didn't carry much tamiya either. So remember that when you make your final decision on what car to get. Actually that just reminded me, I have a losi XX4 that I just cleaned up that I might be willing to sell if you were interested. New tires, wheels, body, wing, turnbuckles, ball cups, blue screw kit, belts, and spur gear. Pretty much everything that wears was replaced and hasn't been ran. Literally like-new condition. It even has a graphite chassis. Anyway, if you're interested PM me. Good luck!

-J

[BQuicksilver]

Go ahead and PM the asking price, but I'm probably set on the DI unless the price is very low. Partly because my friend will be running the same rig, and we can share parts from that point. Heck, we're thinking about buying an extra just for parts at the price of a DI roller.

I already have some decent ESC's, so the brushless does have to make a big difference if I am to commit there. That being said, we both agreed that we'd prefer to have a cheaper chassis and put the $$ into the electronics, hence the brushless questions.

[scoob]

I agree with everyone, get the MM5700. You won't have any trouble with that triple again. Gear it about the same as your 12 turn to start and go from there. You will have impressive runtime too, considering the power

A guy at a local track had the 5700 with lipo in a XX4 and he was clearing the 8th buggy triples easily, gives an idea of the power.

Good luck.