6th Scale Crawler Project (bumps & snags)

[Trucks Women & Beer]

Let's try this again, site dumped my last tread when I posted it.:-x

I have built a 3 link T-Maxx based 6th (actually 5.75 scale) scale rock crawler (sorry no pics, I'm to low-tech). To keep project costs down I decided to use the standard Traxxis EVX speed control, but I can't seem to get any real power from it. The power system has been modified, here is a list of those mods:

I am running a single 55 turn lathe motor with a single 7.2V Venom 3000 through an EVX. The EVX has one of the two battery leads "looped". The lack of power provided by the EVX to my steering has been suplimented by a 7.2V 3000 (regulated to 6 volts) booster pack plugged directly into the stock Traxxis reciever "B" port. Power is delivered to J&B locked diffs with 72/18 drive gears, out to standard Monster GT tires on heavilly offset rims.

Most of the time this car will not turn the tires once the tires have bite on the rocks.

Is it possable to run two 7.2V 3000's into the EVX and out to the single lathe motor?? (I have experience running 2 batteries into a Super Rooster and out to a single Traxxis Titan with 72/9 gears.)

I appreciate any information you guys can provide, Thanks

 

[RANOVRU]

From what I've been told the stock Traxxis reciever knocks whatever is coming from the ESC down to 4.8V. So if you're runnign a power hungery servo then a reciever pack is the way to go.

Don't know about the batts but I have wondered the same thing so I hope someone will chime in.

Also, I would go with a 72/9 set up...

 

[Trucks Women & Beer]

72/9

I have a 9 tooth pinion I can use, but I was afraid I'd loose wheel speed for hill climbing and occasionally getting the tires warm on a rock that wont grip.

 

[donkeykong]

If you run 2 packs to a lathe or any other engine designed for 7.2 you will fry it. Have you tried running a second lathe motor. It should give you twice the torque but will also cut down your run time. Or use the lower gear and try running a 7 cell battery to give a little more juice, you could actually take it off the pack you are useing to power the servo. Since you are limiting it to 6v anyways. Just some ideas

 

[Trucks Women & Beer]

Battery questions

That's an interresting idea. But I'll admit that I don't have as much experience in actually modifying the battery packs themselves.

Just to make sure I understand your idea; your saying that the single 7.2V battery with an additional cell (preferrably identical the the other 6 in the pack) will give me more punch to the motor but running 2x 7.2V's would fry it?
If this is true, what is my limit?
How many cells can I add to a pack to beef it up before it becomes more than the lathe motor can bear? (I have grand visions of a triangular 9 celled pack foating around in my head now!)

 

[RANOVRU]

If you're worried about power/wheelspeed just throw another lathe on there. I run twin Integy 55T's with a 72/9 set-up and it's got plenty of torque/wheelspeed, all you'll ever need.

It'll add some wieght but hey, you're building a 1/5-1/6 scale rig anyway...it's not like it's going to be light. One extra lathe won't make hardly any difference if you're bilding something that big...

 

[TwistedCreations]

run that lathe on 14.4 volts. It will scream :lol:

A few people have done it with no problems

 

[donkeykong]

When you put a 7 cell on a battery you up the volts to 8.4 giving the engine a bit more juice. When you run the 2 batteries it goes up to 14.4. I ran my lathe with dual batteries and it got pretty hot pretty fast, I would keep a close eye on it if you try. As for as will a 9 pack work...make it and run it, if you smell smike than no it wont work, if it has tons of torque and wheel speed with no unreasonable amout of heat...let us know I might give it a try. Also check your charger I know some charges have limits to what they can charge so it would be pointless to build something you cant even charge.

 

[Trucks Women & Beer]

55t

Yeah, at this point weight isn't too big an issue, normally I add weight to a crawler. This is the first time I've used the Integy 55 turn lathe motor. I have another one that I can add to the car, but now I'm interrested in what thier capasities are exactly. Maybe knowing that will help me to figure out what the optimum battery combination might be.
As far as charging a larger battery, I'm not sure what my charger is capable of, or who manufactured it, the company who makes it calls it a Prophet.

 

[Cloak]

Since we're sort of on the subject, can I make a y harness to plug into the esc to run 2 lathe motors? How would I wire it?


esc side with deans, one line going from positive on deans to positive on motor 1, then negative to negative on positive on motor 2, then negative on motor 2 back to negative on the esc?

Will that provide enough power to the motors but halve the run time or is that not the right way around?

 

[donkeykong]

What model of prophet?

And cloak if you are running a evx then it already is wired for 2 motors and if not what esc are you running?

 

[Cloak]

And cloak if you are running a evx then it already is wired for 2 motors and if not what esc are you running?

Ahh, if only I was. I'm running el cheapo off ebay, complete with the double tap reverse.

 

[John Deere]

Not trying to hight jack, and also trying to prevent from making another thread for one simple question that can be answered here. Can I run to lathes in a stock e-maxx and still go to comp crawls with it? Not that i am going to just curious if that legal to do in comps?

 

[donkeykong]

I have never competed but from what I understand of the rules there is nothing stating the engine limits. Only a limit on wheelbase, steering and tire size. But like I said I have never competed so there may be an unofficail rule that I dont know about

 

[CSR]

Each individual cell puts out 1.2volts. The lathe motor is designed to run on 12volts=10 cells.

I've seen a Clod with lathes running on 14.4 volts...... it was a rocket! It could still crawl really slow, but like you mentioned earlier, had tons of wheel speed to heat the tires up! :twisted:

 

[TwistedCreations]

well are the clods illlegal?? Same goes for your maxx with 2 motors

 

[John Deere]

I got you twisted thanks. Thats all I nedded. i am gonne use to motors on my maxx based crawler then once i start my mantis. Thanks again.

 

[Trucks Women & Beer]

T connections, and other picture postcards.....

I have used T connections on a SuperRooster and have put 2x 7.2V 3000's through the Rooster and into a single Traxixs stock Titan motor. This was the only way I could turn tires on a 90 degree appoach, 72/9 gears, LST tires with a 1/4 pound of BB's in each tire, beadlocked. Used that setup on a T-Maxx for at least 20 hours. The motor got literally to hot to touch, but never burned up. And even if it did, I have another from the same Maxx so it is kind of expendable. Both batteries were to tired to turn tires after 15 to 20 minutes of hard climbing.

I think I figured out my power issues.
First I have a confession to make, my drivelines were contacting my skid plate at both ends on full compression.
I know, what a dope, get the giggles over with now....

Thanks CSR for your input, now that I know what the late motor is capable of, I may try a 9 cell (to keep things neat) to get more run time. I tried it again this afternoon and the truck started to grunt with her tires on the rocks after about 10 minutes of hard running.
I may still try running 2 lathes on her later, but that would put me up to a total of 3 full 7.2V packs on this truck. As things stand now I have a lot of body roll and top weight.
The 72/18 gear combination seems to give me the wheel speed I want on occasion and still have the control I need for creeping speeds.

Now that I've had a successful trial run, I've found that I will need rear steering to compensate for the 18 inch wheel base and large amounts of driveline torque roll. I'll keep y'all posted on my progress.