How to select a brushless system?

[MickeySilver]

SO I have read up from a few different sources and am ready to choose a system. I have choosen to go with a Neu motor (possiblt this one http://www.impaktrc.com/product_info.php?products_id=1971) The MMM V3 ESC, and not decided which batteries to go with.

On the neu motors whats the difference between the 1512 and the 1515?

How do you determine what motor ESC and batt combo will work the best? I assume the V3 isnt really much of factor, but more more important to find a properly matched motor and batts. IS there a certain KV you should try and be around? ie: 2200kv motor X 22.2 V batt = 48840 RPM

I guess some info on what I expect to run would also help. Will be running in MT class with 15 minute mains. So I would like to be able to run min 16 or 17 minutes to complete the race.

Perhaps I should consider running 2 2cell packs instead?

Any help is apreciated. Also please considering offering some reasoning behind your suggestion, as I would like to learn about these things not just be told what works. Been racing nitro for 2 years and dont really like the tuning of them.

Thanks
Tim

[asheck]

Check out the regular E-revo Forum FAQ sticky.There is alot of info there.Can't really help a racer.

[brushlessman]

i would run 2 2s packs instead here ya go http://www.maxamps.com/proddetail.php?prod=MA-6500-EREVO-Pair&cat=207 (very good lipos) they are brand new 30c cells with 195 amps continuous. the 1515 is longer than the 1512. that neu you listed is the one you need.

[Unsullied_Spy]

http://monster.traxxas.com/showthread.php?t=430233
This will help a lot. The 1512 is shorter than the 1515 and thus less torque. I ran a 1515 1.5D in my E-Revo and it would spin the Talons on asphalt easily. 30+ MPH wheelies on 4s wasn't a problem. If you're looking for controllable power, the 1512 is plenty. The 1515 builds some insane torque and will easily push your Revo past 60 MPH with proper gearing and batteries.

That motor will be nice on 4s, and absolutely brutal on 6s (probably rip your driveshafts and diffs up). 22/62 with that motor on 4s lipo would be a nice combo, IMO.

For that kind of run time, you may want to look into the TrueRC 8000mAH 15C lipo packs, those should give you that kind of run time even under race conditions. The 2s 8000mAH packs just barely fit, and are the highest capacity cells that I know of that will fit, unless you can get some Rhino lipos and parallel them together, but IMO the TRCs should be fine.

For racing I think I would choose the 1512. It will still accelerate like mad and you should be able to break 40 MPH on 4s without any heat issues at all and will take less power. The 1515 is a lot of motor, so unless you have a lot of room you won't be able to use all the power.

[powerslider]

For racing you want a smooth controlable system so 4s is plenty of voltage, 6s is way to much power on a track unless it's huge. The 1515/1Y is a good choice, I would go for the MMM combo as it's been tweaked for this type of use or the Techno/Neu motor (same wind). The regular Neu motors were designed for planes so they are open on the ends, you need to keep dirt out of them by wrapping with a breathable fabric or sealing them up. The Techno version is closed on the ends but you still need to seal around the wires. The 1512 is a shorter less powerful motor than the 1515 and not the best choice for the size and weight of an E Revo, it may overheat. Check out the F.A.Q,s lots of good info there from people with experience. For batteries I would go with SMC either 2s 5200 24c or the 2s 5000 28c hard cased lipo's with 22/62 gearing to start. Good batteries are very critical for strong power delivery so choose carefully.

I have this setup and it runs very strong but is still very drivable with a little throttle control.

As for picking componants, you want your motor rpm to run in the 30 to 40,000 range generally for best efficiency and cool temperatures. A motors kv rating relates to rpm per volt so you can use that to pick components to put you in that rpm range. Neu motors are good to 60,000 rpm but I'd stick to the previous range as a guide. Proper gearing will have to come from testing at your track but my starting point should be good for 40mph or so...

[mkrusedc]

Check out this thread for info about Neus:

http://monster.traxxas.com/showthread.php?t=438944&highlight=understanding

But in answer to your question:

The second two numbers denotes the rotor length. For example xx09, xx12, and xx15. Larger numbers means a longer rotors. A longer rotor generates more torque.

[brushlessman]

TrueRC 8000mAH 15C lipo packs, those should give you that kind of run time even under race conditions. The 2s 8000mAH packs just barely fit, and are the highest capacity cells that I know of that will fit, unless you can get some Rhino lipos and parallel them together, but IMO the TRCs should be fine. why get lipos that are only rated for 120amps ( the motor IS rated for 110amps and can spike much higher than that.) for $30 more you can have some packs that can take 195amps constant.

[HoovHartid]

why get lipos that are only rated for 120amps ( the motor IS rated for 110amps and can spike much higher than that.) for $30 more you can have some packs that can take 195amps constant.


correction...for $30 more you can have batteries that CLAIM to take 195A constant and are 1500mah less.

[MickeySilver]

That Neu write up was JUST what I was looking for mkrusedc. That info on the rating is just what I was looking for.

So now for batteries. I agree with brushlessman on the amp rating for the batteries. Would want something that can handle the full potential of the system safely. With that said, how is the C rating calculated? Is it 5 amps per c? ie: 1c=5amps, 10c=50amp, 20c=100amp, 25c=125amp?

As for the gearing 22/62 seems to be the consensus. Is the stock spur 62 teeth? I know it is plastic, should I be upgrading to metal? I have never really shredded the plastic gear spur in my nitro revo, but this will be alot more tourqe.

Lastly IS there a single motor motor mount out there that is recomended? I currently just have the stock mount designed for twin titans.

Again thank you everyone for all your help! this forum is an awsome resource to learn and find answers to my questions. Hope to be up and running for the end of Feb for Canadian Winter Nationals in Red Deer Alberta. Anyone interested in participating in this HUGE canadian racing event should come! Would like to see a big turn out of 1/8 electrics, as this is the first time they are allowing them.

Tim

[brushlessman]

its simple take a 6500mah pack = 6.5ah (amp hour) x 30 = 195amps.

correction...for $30 more you can have batteries that CLAIM to take 195A constant and are 1500mah less.
you dont know that yet btw. those trc packs are only rated at 120amps c
those ma's are rated at 195. i dont think there is a 75 margin between the two. the extra ah will not matter if the pack will not provide the power of the 30c packs i mean thats halve the power! the extra mah will not necessarily
give a longer runtime if the pack has to strain to keep up with the other pack. the 6500 will run cooler and more efficient. and have more power and punch to boot!

[powerslider]

That Neu write up was JUST what I was looking for mkrusedc. That info on the rating is just what I was looking for.

So now for batteries. I agree with brushlessman on the amp rating for the batteries. Would want something that can handle the full potential of the system safely. With that said, how is the C rating calculated? Is it 5 amps per c? ie: 1c=5amps, 10c=50amp, 20c=100amp, 25c=125amp?

As for the gearing 22/62 seems to be the consensus. Is the stock spur 62 teeth? I know it is plastic, should I be upgrading to metal? I have never really shredded the plastic gear spur in my nitro revo, but this will be alot more tourqe.

Lastly IS there a single motor motor mount out there that is recomended? I currently just have the stock mount designed for twin titans.

Again thank you everyone for all your help! this forum is an awsome resource to learn and find answers to my questions. Hope to be up and running for the end of Feb for Canadian Winter Nationals in Red Deer Alberta. Anyone interested in participating in this HUGE canadian racing event should come! Would like to see a big turn out of 1/8 electrics, as this is the first time they are allowing them.

Tim

Stock spur is 68, get several different spur gears as there cheaper than pinions ( 65, 62, 58, 56, all used with the 22 pinion will give you a good selection) Do not go metal, stay with the plastic spur. As for a motor mount I stayed with the stocker, just duct taped the opening to seal the second motor opening.

As for batteries I'm not going to push any particular brand, some people swear by brand X others swear at them. Do your research before you lay the money down, some are under rated others are over rated. Enerland cell based packs are among the best, go for 5000ma min and a high C rating over 20 IMO.

[mbeatle]

its simple take a 6500mah pack = 6.5ah (amp hour) x 30 = 195amps.

you dont know that yet btw. those trc packs are only rated at 120amps c
those ma's are rated at 195. i dont think there is a 75 margin between the two. the extra ah will not matter if the pack will not provide the power of the 30c packs i mean thats halve the power! the extra mah will not necessarily
give a longer runtime if the pack has to strain to keep up with the other pack. the 6500 will run cooler and more efficient. and have more power and punch to boot!

I think what WhoFarted is getting at is that Maxamps have notoriously overrated their packs in the past. It's likely not a 75A difference, for better or for worse.

[sadclown]

why not just wait for the MMM motor?

[MickeySilver]

If you mean the one that is coming out in a combo, I think a Neu motor will better quality. But I could be wrong.

[skeppley]

The combo is already out.
A few people have one on the way already ;) ;)

http://www.superfastrc.com/mamba-monster-esc-combo-with-2200kv-m2200.html