Brushless motors

Brushless motors
View related threads: (in this forum | in all forums)

Logged in as Guest

Users viewing this topic: none

Printable Version

All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> RC Drag Racing >> Brushless motors

Page: [1]

Login

Message

<< Older Topic Newer Topic >>

Brushless motors - 1/25/2008 4:47:57 AM

driftlord

Posts: 13
Joined: 11/29/2007
From: Isabela, PUERTO RICO (USA)
Status: offline

Hey Guys, I'm currentl moving over to electric drag racing as I've gown tired of dealing with gas powered cars. I want to stay in drag racing but with less hassle!! I just bought a pro mod from GMS and I need a decent setup to run at least 1.80 or less. I was told that getting a mamba 7700 and a lipo battery that produced 11.1v. I don't know nothing about brushless nor lipo for that matter so I wanted to ask you guys here in the forums. I need a small guide into what is a brushless motor, what are the numbers acompanied when I look at them in a catalog...example(5700kv,6900kv), can I use any battery? What exactly is the difference using a 2cell lipo from a 6 cell lipo? Any help would be greatly appreciated!!

Post #: 1

RE: Brushless motors - 1/25/2008 6:59:46 PM

ac hauswald

Posts: 143
Joined: 3/13/2004
From: Houston, TX, USA
Status: offline

quote:

ORIGINAL: driftlord

Hey Guys, I'm currentl moving over to electric drag racing as I've gown tired of dealing with gas powered cars. I want to stay in drag racing but with less hassle!! I just bought a pro mod from GMS and I need a decent setup to run at least 1.80 or less. I was told that getting a mamba 7700 and a lipo battery that produced 11.1v. I don't know nothing about brushless nor lipo for that matter so I wanted to ask you guys here in the forums. I need a small guide into what is a brushless motor, what are the numbers acompanied when I look at them in a catalog...example(5700kv,6900kv), can I use any battery? What exactly is the difference using a 2cell lipo from a 6 cell lipo? Any help would be greatly appreciated!!

Hey driftlord,

Does the rest of the PR gang know you've come over the the side of 'truth, justice and the American way', that is, RC electric?

j/k That rowdy PR group has pitted next to me the last two IMDRA Worlds. They're a lot of fun. Yeah, electric. It's different from nitro. It has it's own challenges as you shall soon discover. I'd say hang onto your nitro stuff for a while. Just in case you decide electric is not your bag.

BL motors. I'll leave that to the experts. I've recently cut over to BL, so don't know enough about it to make a recommendation. I run a Novak 4.5 HV and HV Maxx controller. But that set-up is an anomoly. I think most of the guys are running MM (Mamba Max). They need to weigh in to help you select the correct package BL motor/controlller.

LiPo's? Basically they provide 3.7v per cell. The more cells, the more voltage. 2s = 7.4V nominal. 6s = 22.2V nominal. The 3s Lipo I use in my Top Fuel Electric is 11.1V nominal; charges to 12.6V. The 2s1p LiMn I use in my bracket car is 7.4V nominal; charges to 8.4V. That's all I know about that.

If you're going to run in sanctioned RC Drag Racing events, I'd recommend checking the rules first to see what is allowed for LiPo before you buy.

Hope this helps.

OZ

_____________________________

Arnie Hauswald Racing 1943
RC Electric Drag Racing

(in reply to driftlord)

Post #: 2

RE: Brushless motors - 1/25/2008 7:39:18 PM

driftlord

Posts: 13
Joined: 11/29/2007
From: Isabela, PUERTO RICO (USA)
Status: offline

hahahaha!! Lets keep this between you and me buddy!! As you know Nitro Drag Racing is big here on the island but electric is a long forgotten aspect of rc. I plan to bring back the good old days of charging batteries with no noise, oil mess, or the stench of gas. I have recently sold all my gas cars and replaced them with electric kits. I will do the same with Drag racing. I wanted to know if an ESC is necessary for brushless systems! Usually with brushed motors it was possible to have the battery conected directly without the speed control. I also want to know how fast are you going on the strip?

Thanks for the help, it's good to know people that are williing to help!!

(in reply to ac hauswald)

Post #: 3

RE: Brushless motors - 1/25/2008 8:33:06 PM

ac hauswald

Posts: 143
Joined: 3/13/2004
From: Houston, TX, USA
Status: offline

O.K. driftlord. But good luck keeping any kind of secret in the RC drag racing world.

A BL requires an ESC. Actually, I thnk they call them controllers to differentiate them from brushed motor ESCs. The MM's come with a software/firmware package that allows the racer to set operating parameters and limits on the motors. Not sure which of the MM's come with that. Some racers consider that feature a competition multiplier. Being able to make changes b/w rounds.

Haven't heard of anyone doing a slam switch set-up on a BL. Don't think BL's work the same as brushed motors. Think someone said BL's are AC, not DC. But again, the smart guys need to weigh in and help you there.

First time out, my 3s TFE went into the 1.9's three times with a best of 1.949. Best speed was 60.3mph. Still have lots of work to do to get it right. My TFE is double reduction belt drive. That hampers performance. You should get into the 1.8s easy with what you have.

Hey you're gonna love runnin the LiPo's. Heck, I made 8 passes with my 2s bracket car and never even hooked up a charger. Made 2 timing passes and 3 qualifiers with the TFE. Put it on the charger just to see what it would take. Nada. It was still full up. Whew, I don't miss that round cell peaking chore one bit.

So, O.K., Snellemin. I know you're lurking out there in cyberland just strainin at the bit to answer up on this thread. You got lots of BL knowledge.

OZ

_____________________________

Arnie Hauswald Racing 1943
RC Electric Drag Racing

(in reply to driftlord)

Post #: 4

RE: Brushless motors - 1/26/2008 12:35:58 AM

studysession

Posts: 9894
Joined: 4/15/2003
From: ..., PA, USA
Status: offline

Any pics?

_____________________________

http://studysession.com
http://www.rcuniverse.com/forum/m_6346863/anchors_6346863/mpage_1/key_/anchor/tm.htm#6346863

(in reply to ac hauswald)

Post #: 5

RE: Brushless motors - 1/26/2008 1:38:06 AM

snellemin

Posts: 730
Joined: 3/22/2007
From: Tomball, TX, USA
Status: offline

You'll need a ESC for brushless, as it's a 3phase motor. The only secret in electric dragracing, is the configuration of you your chosen electric hardware.

AC, I would stay with the current vehicle you have and just change the powersource, and ESC motor combo.

_____________________________

check out www.Hamdrl.org
Snelle-RC, A123 Racer

(in reply to studysession)

Post #: 6

RE: Brushless motors - 1/26/2008 5:12:31 PM

ac hauswald

Posts: 143
Joined: 3/13/2004
From: Houston, TX, USA
Status: offline

quote:

ORIGINAL: snellemin

You'll need a ESC for brushless, as it's a 3phase motor. The only secret in electric dragracing, is the configuration of you your chosen electric hardware.

AC, I would stay with the current vehicle you have and just change the powersource, and ESC motor combo.

LOL Snellemin.

The chassis's O.K.; just the electronics are junk?

j/k. I know what you mean.

Big changes coming in the rear clip of the R2E. Going to single reduction pinion/spur instead of the power-soaking high-mass revolving belt drive chassis it has now. Single reduction is where the performance in RC drag racing is. That's why I say driftlord won't have any problems getting into the 1.8's with his Walbern chassis. Hey, look at the performance Jmack is getting with his Walbern BL. He had to ADD four round cells as BALLAST up front to keep it down in the wind the last time he ran SA. He still went 2.1's!!

Oh! Driftlord, whatever ESC/Controller package you decide on, be sure it has 3.0 voltage limiting circuitry for LiPo cells. That's where most of the fires with LiPo's occur. A cell gets discharged below 3.0V and flames when it gets a recharge. I'm running Novak "Smart Stop" on both LiPo and LiMn packs. It's external to the ESC/Controller b/w the battery and ESC/Controller. It stutters the ESC at 3.2V and shuts down the ESC at 3.1V. Prevents overdischarge. Extra wiring is a PITA and adds weight. But, it's a must have.

AHR43 committed all its motor funds to this Novak 4.5 HV package. So gotta make it work this year. SR (Single Reduction) chassis should "wake it up".

Don't be sad, Snell.

I'm saving all the parts so I can put the R2E back together as a 2s double reduction brushed motor rail. Kinda my like a Jr. Fuel rail for 2.5 Index and Bracket. That'll be after I build my own complete TFE chassis - later this year, in time for the IMDRA Worlds.

Hey driftlord, hope this helps a little more.

OZ

< Message edited by AHR43 -- 1/26/2008 5:14:38 PM >

_____________________________

Arnie Hauswald Racing 1943
RC Electric Drag Racing

(in reply to snellemin)

Post #: 7

RE: Brushless motors - 1/26/2008 7:36:03 PM

snellemin

Posts: 730
Joined: 3/22/2007
From: Tomball, TX, USA
Status: offline

AC, That motor will have enough torque for a single reduction tranny. Just the powerband will move a bit.

< Message edited by snellemin -- 1/26/2008 7:37:33 PM >

_____________________________

check out www.Hamdrl.org
Snelle-RC, A123 Racer

(in reply to ac hauswald)

Post #: 8

RE: Brushless motors - 2/2/2008 11:23:37 AM

1maxdude

Posts: 130
Joined: 2/2/2008
From: , WA, USA
Status: offline

The motor kv is rpms per volt. The mamba max is a good choice with all the little tweaks you can do. The higher the kv, the more rpms you can get per volt. The mm 6900 and 7700 are limited to 2s lipo BUT. If you do it up right and keep the rpms away from the 65,000 area you could probably get away with burpin the 7700 with 3 or maybe even 4s for drag racin. Each lipo cell is equal to 3.2v and is usually designated with an s as in each cell is wired in series. The mamba max esc does have built in lipo cut off which is necessary to run lipos, you must make sure you dont over charge or over discharge lipos; ie. below 3v per cell. You can have extremely explosive results from over/under charging and/or puncturing these cells. Special charger and balancers are required as well for lipos. They pack way more punch, have much higher capacity and weigh approx. half as much as similar sized nimh batteries. Im not all that knowledgeable about this sort of thing, just stating what I think I know. I personally just bought a MM 6900 to bash with and just purchased a 2s lipo, so Im pretty new to this as well. Several precautions need to be met with lipos. You also need to be careful when putting more voltage to the speed controller than you're supposed to, if you run a mamba, 11.1v lipo is max, I've heard of people running 12 cell nimh, but you have to power your reciever with a seperate battery pack if you do that.

(in reply to snellemin)

Post #: 9

RE: Brushless motors - 2/5/2008 5:37:29 PM

snellemin

Posts: 730
Joined: 3/22/2007
From: Tomball, TX, USA
Status: offline

If you keep your amp draw low enough, then the mamba ESC will handle 5s with no problems. I run 6s1p A123 with the mamba ESC with success. I have 10 motors and only 2 are 7700kv. The rest are below 5000kV. I can't run the high kv motors with more then 4s1p A123. It will just overheat/blow the ESC. I've done it before and overheated the batteries, motor and speed control. It's easier and cheaper to make power with voltage then with amperage.

_____________________________

check out www.Hamdrl.org
Snelle-RC, A123 Racer

(in reply to 1maxdude)

Post #: 10

Page: [1]

All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> RC Drag Racing >> Brushless motors
Page: [1]

Jump to: