2 esc's on clod?

[scruff007]

Can I wire the rx wires on 2 esc's together then plug into chan. 2? My nephew wants 1 esc, motor and batt. for each axle to fight clodstall. Which sounds like it should work. He has a 2 chan. Tx and wants to have throttle for both esc's on the trigger of course. I thought I could use a Y harness I've got but found out that it just reversed the esc function. In other words, when you pull the trigger full throttle foward, the fronts start turning like nornal but the rears take a second to start going and move about half the speed. The esc's have a delay in reverse. I still had to reverse the polarity on rear motor to get all 4's to turn the same direction. All the Y harness is doing is reversing esc funtion and not motor rotation. The esc's are both exactly the same - Duratrax autosports. I hope this all makes sense. What I figured I could do is basically wire the esc's with a Y harness but without the reversing device going to one of them. Will this work. Is that putting twice the voltage to the Rx of does it pull just the voltage it needs to work from the battery and no more? Thanks in advance.

[dezrik]

Try buying RX's exactly the same so when you press the trigger it tells both motors to go

[Insomniac]

Originally Posted by dezrik

Try buying RX's exactly the same so when you press the trigger it tells both motors to go

with the same frequency? sounds a bit mad!
I'm surprised the y harness doesn't work, I think you need to cut one of the wires on one arm of the y-harnes, as the RX is getting voltage from both ESCs. Unfortunately I haven't done this myself, but I know someone will be along to advise which one!

[Grizzly4x4]

You can buy Y harnesses that do not reverse.

Yes, you can wire two ESC's in parallel to have one drive the front motor and one drive the rear motor.

However this will not stop clod stall. Clod stall is caused by the ESC sending the same voltage to both motors but each motor has a different load on it. The load causes resistance.
I=V/R V=voltage, I=current, R=resistance

If you have the same voltage but different load (resistance) then current will not be the same.

The only way to get the two axles to always pull the same is to connect them with a driveshaft or use some type of independent front/rear throttle control such as on a 4 channel radio.

You can certainly try running parallel ESCs but I think you will be disappointed with the result.

[JK Power]

Would not double battery packs solve that problem?

One pack per esc per motor, and esc´s are parallel with a y-harness to receiver.
It should not over load receiver because parallel wiring,same voltage but double capasity.

Then each motor has it´s own power source,esc and voltage flow.

That way it does not matter how much resistance there is on any axel, both motors get the same amount of voltage since they have separate esc´s and power source.

Of course a certain amount of movement does require equal amount of energy.
Meaning that if your front tires are on slippery surface they will spin more easily,with same amount of power, while rear tires on the rock and under heavier load will need more power to do so.
In such a case it is required different amount of power to achieve the same wheel speed.

A separate control for both motors.

This "Clod Stall" could be thought in a another way, as in electrical center differential! I know...

[Grizzly4x4]

Originally Posted by JK Power

Then each motor has it´s own power source and current flow.

That way it does not matter how much resistance there is on any axel, both motors get the same amount of current since they have separate esc´s and power source.

Squeezing the trigger on your radio tells the ESC to provide a certain voltage to the motors, not current.
Based on the voltage the ESC is providing to the motor, and the load on the motor (resistance) a certain current will flow through the motor.

It doesnt matter if you have two complete systems in parallel, two ESCs in parallel on one battery, or one ESC, the same amount of battery voltage is provieded to the motors when you pull back on the trigger.

The resistance drop in the wires from the rear motor to the front motor are negligible. Measure it with a multimeter.

[JK Power]

Yup. Your right!

Did figure that out after reading your´s and my own post´s a couple of times.

It´s been awhile since my electronics classes in school!

Ah well, at least I did get a good laugh! On my own cost!

[Grizzly4x4]

Originally Posted by JK Power

Yup. Your right!

Did figure that out after reading your´s and my own post´s a couple of times.

It´s been awhile since my electronics classes in school!

Ah well, at least I did get a good laugh! On my own cost!

You are right about the center electrical differential thing. Now if someone would only figure out how to control it so we could lock it up or open it as we needed.

[scruff007]

Thanks for all the replies fellas. They were very helpful. What I ended up doing for now was wire both esc's into one plug. I figured that the Rx was getting same voltage wether the esc was reversed or not. It does have a little more umph but still has stall. Again. Thanks.

[BigRedB2]

Originally Posted by Grizzly4x4

You are right about the center electrical differential thing. Now if someone would only figure out how to control it so we could lock it up or open it as we needed.

Woudlnt a variable resistor somehow operated by a servo do that? no...actually..it would only turn on and off one motor....but..that would be a cool dig.

Guess the only real way to eliminate clodstall is swap to a TXT.

What scruff and i are trying to accomplish is a hill climbing clod. Ive got a nylint body mounted on rockbull chassis and the extra weight of the nylint body puts alot of load on the clod drivetrain going up hill. The Front wheels spin like mad and i get NO spin on the real axle. i realize the rear will never turn as fast as the front while going uphill, but i would like it to atleast assist in the climb. other than my current idea of 2 ESCs and two batteries.....what else can i do?

[JK Power]

You need a 4-channel tx, two esc´s in their own channels so you can give throttle to the both motors separatly.
By pushing both sticks at the same time.
Then you can give more power where it is needed and compensate for the resistance.

I´m planning on these ones(cheaper):
http://www2.towerhobbies.com/cgi-bin...=LXBCP2**&P=ML

Or this(better):
http://www.spektrumrc.com/Products/D...ProdID=SPM2460

The spektrum would have more fine tuning adj. and mixing with NO problems with frequency.
Just have to order from LHS with throttle return spring!

[Grizzly4x4]

Originally Posted by BigRedB2

Woudlnt a variable resistor somehow operated by a servo do that? no...actually..it would only turn on and off one motor....but..that would be a cool dig.

Guess the only real way to eliminate clodstall is swap to a TXT.

What scruff and i are trying to accomplish is a hill climbing clod. Ive got a nylint body mounted on rockbull chassis and the extra weight of the nylint body puts alot of load on the clod drivetrain going up hill. The Front wheels spin like mad and i get NO spin on the real axle. i realize the rear will never turn as fast as the front while going uphill, but i would like it to atleast assist in the climb. other than my current idea of 2 ESCs and two batteries.....what else can i do?

If this will be a dedicated hillclimber then you could use the resistor idea to slow down the front end. I used the big resistor that comes with the clod mechanical speed control years ago. The resistor has two stages, I used one stage to slow down the front by wiring it to a switch that would put the resistor in series with the motor. It worked great but it slowed the motor down alot, maybe too much for hillclimbing but it might be a start. You can also buy power resistors so you could experiment with what works best.

Have you tried running a pinion gear 2-3 teeth larger on the front motor? This would increase the load on the front motor and slow it down, unless you are lifting the front tires, then it would spin really fast. Running 1-2 teeth more on the front pinion works well on the rocks.

Sounds like you really need more torque on the rear end though. How about this: Run a 65T motor on the rear axle with an 8 tooth pinion, a 45T motor on the front axle with a 10 tooth pinion, and use a Novak SuperDuty ESC or EVX to run 14.4V to the motors to get your wheelspeed. The rear axle will then have much more torque than the front.

Just some ideas.

[BigRedB2]

well...running the different turn motors and pinions on the axles would kinda hurt in a hillclimb. you want the front to spin more than the rear, other wise you would flip over backwards..i just dont want the rear to stop spinning or atleast be able to have enough power to help the front pull.

Scruff was right about the extra umph the dual esc gave it. I still have clodstall, i guess the only REAL resolution to my problem would be to move up to a TXT.

i dont think mix matching motors and gears is the way to go unless you do have a variable resistor you can control from your tx. Once you get on flat ground the whole system would be fighting against itself, so you would need to be able to trim out one motor to compensate for the difference between the two.

[JohnRobHolmes]

Dont buy a txt, buy a 4 channel stick radio! Independent front and rear throttle completely eliminates clod stall problems. If the rear stalls out you just give it more throttle than the front!

[BigRedB2]

Yeah..see..even that doest achieve my goal. The front ALWAYS has to spin at full steam when doing hill climbs and the rear needs to atleast turn some...as much as possible...full steam on the rear as well is the ultimate goal.

By backing off the front throttle you lose wheel speed and forward momentum on hill climbs. I need the rear to have enough power to push me over bumps on the hills other wise they act as anchors and the front just digs in.

Guess i havent been real clear with the use of this truck.

Its mostly a back yard basher. here in NC we dont have alot of rocks, what we do have is creekbeds with mud and high banks. In order to climb outta the creek beds and up the banks i need high wheel speed from all 4. I can make it about halfway up a hill the TLTs in the group i wheel with do with ease. I want to level the playing field.

Clodstall isnt a real huge problem on the rocks, generally the weight is evenly distributed all around and the front has enough traction to pull the rear over and usually the rear doesnt stall to a complete stop.

[JohnRobHolmes]

Sounds like you need a different setup then. Either your tires aint cuttin it or your suspension isnt set up right and your motion is wasted into suspension travel. What tires are you running? Do you just loose momentum and die halfway up? Could be the wrong motor for what you are wanting to do.

[BigRedB2]

ive got Integy 55t with stock pinions (temporarily, going to 8t). Im running moab xls, with about half foam so i have plenty of foot print. The moabs are the best gripping tire ive seen. the hills are composed of hard packed dry dirt and of course theres loose "dust" here and there. ive got the suspension set up stiff in the rear and soft in the front to keep the nose pointed down rather than flipping backwards...theres really no other way to do it. i lose momentum halfway up because the load (weight) on the rear axle causes it to stall usualy when it hits a bump and has to climb over it. the front tires continue to spin but just cant drag the truck any further. The only thing i can change with my setup to help is weight distribution, i could move my batteries to the front (they are currently sitting in the front seats) but that would screw with my water fording ability and i dont think its gonna solve the issue.

Again, in the end, the only thing that is gonna help is a transfer case locking the front and rear axle together...and ya cant get that with a clod.

The end result was that the dual esc didnt do what i wanted it to do, but i got a result i wasnt expecting. A small boost in speed and thats gonna help out when i go to deeper gears.

FYI....this is a 20 lb rig. a detail i should have disclosed sooner. And thats a dry weight..keep in mind the tire foams are usually soaking wet when im running it so at run time its closer to 25 lbs.

[JohnRobHolmes]

Simple solution, volt up. What esc's are you running? 55t motors can take 12 cells pretty easy. Gear down to 8 or 9t pinions and volt the hell outta those motors! You will make those climbs no sweat

[dezfan]

Are you running out of power or traction first?

[Grizzly4x4]

Originally Posted by BigRedB2

ive got Integy 55t with stock pinions (temporarily, going to 8t). Im running moab xls, with about half foam so i have plenty of foot print.


FYI....this is a 20 lb rig. a detail i should have disclosed sooner. And thats a dry weight..keep in mind the tire foams are usually soaking wet when im running it so at run time its closer to 25 lbs.

Herein lies the problem.

I have had trouble with the motors stalling on a 9 lb rig when using stock pinions and Imex JumboMaxx Swamp Dawg tires.

With a 20 lb rig and 7" tall tires your motors dont stand a chance with stock pinions. Definately run 8T pinions (I still think a 9T in the front would be good) and with that much weight you really need to be running 10-12 cells like jogn said.

You should talk to John about running brushless also.