Mamba Max motor possible mis-labeled?
 

Well, I've got my Mamba Max setup running around in my jato with the 7700 motor..... Way way way slower than I expected with any battery I used...

Gearing is good, I get about a 14:1 ratio in 1st gear, and a 10:1 ratio in 2nd from the pinion to the wheels... It's just slow as stink :(

Top speed is slightly faster than a brushed motor, but nowhere near the power to weight ratio or top speed that any of my 18th scale mambas have.... My Mamba'd RC18T would smoke this thing in every aspect, acceleration and top speed.

Is it possible my 7700 is not actually a 7700 but one of the lower kv motors? Could this explain the seeming lack of RPM?

Specs:

Jato, stock 2 speed trans, diff ect
55t spur
15t pinion
Mamba Max ESC
MAmba Max 7700 motor
GP 3300 cells at 7.2v
Deans connectors

And honestly, I'm very very dissapointed in the setup... Everybody is praising this thing and IMO it sucks :(

what temps is it running, how good are your packs?

Are your battery packs stick packs or side by side?

Have you calibrated the throttle with the endpoints on your radio set to full?

If all else fails, you can contact Castle on Monday and ask them what might be going on.

I suppose it is possible, but unlikely. You could contact Castle and see what they say.

Even if it was mislabeled, you should still get some very good speed with the 4600 or the 5700. I'm getting a little over 45mph with the 4600 on 2s with wheel-spinning torque in my Jato. I even have the start power turned down and timing as low as possible. I can't imagine running it on 3s!

The 7700 is a very hot motor. That would probably be a 3 or 4 turn motor using the kv ratings of similarly sized S motors. Therefore, your batteries are probably unable to provide the current needed to get that moving under load. Sometimes it's bette to use a lower kv motor for extra torque and simply use higher voltage to get the speed you want. Plus, the added torque from the higher turn motors tend to be a little more forgiving with misgearing.

Side by side packs. EPA is set to full.

That seems like a logical explaination, however I am experiancing no cogging at all... I would expect to see some cogging at a minumum if the batteries were not good enough?

What would one recommend for a lipo-pack? I'd like to run 3s at a minumum.......

Just for kicks, I tried 14.4v just a few minutes ago, Iirc motor was 110ish, speed controller was 165. Speed is better, but definatly nowhere near what it should be....

Lack of cogging is not an indicator that the battery is "good".

14.4 on a 7700 won't work in your truck... was way overgeared. Besides, 14.4 will destroy any 7700kv motor if you let it spool up.

If you hold the truck in the air and give it full throttle do the tires balloon way up? With 7.2 or 14.4?

What brand/type of batteries are you using?

you cant compare grapes to oranges. The 18th scale stuff is in a class its own, they are weightless and super fast, and sound totaly different. Junk cells will still make them fly, gearing can be off and they still fly. 1/10 you have to start using your brain a little, and in monster trucks even more so.


You are one of the 1000's of people that looked for the highest # expecting the faster set up, and those motors are not the way to go. Sounds like you have generic batteries, which are probably the entire problem. You also need good soldered joints and really good connectors.

What we need to know...
How fast in MPH to do want to go?

Not necessarily. Cogging is simply the ESC not being able to determine where the rotor position is by the back-EMF pulses. If it's turning, however little, you won't cog. What I'm thinking is that you are getting a large voltage drop on your batteries under the heavy current the 7700 requires. Oh, and you defintely don't want to run that motor at 14.4v, that's almost 111,000 rpm!! :eek: ...assuming of course that the batteries actually stay at 14.4v.

If you're looking for batteries for that setup, I'd go with something that has a large Ah and/or C rating to be able to supply at least 100A continuously with minimal voltage drop. Otherwise your lipos will heat up fast and may be damaged.

Personally, the 7700 is not sized right for that truck. Maybe in a 2-3lb vehicle. Don't forget; as kv goes up, torque goes down and that motor may simply not enough torque to get the vehicle moving at a decent speed. Again, I'd say go with the 4600 or lower kv motor, use higher voltage, and gear appropriately. I am almost positive you'll be satisfied.

Tires barely baloon with the truck in the air on 7.2v.

Tires baloon reasonably with the truck in the air on 14.4v.

GP3300 cells in built 7.2v packs. 12awg wire, deans connectors.

The same, if not FASTER than the Jato was originally with the 3.3 motor in it.

Yah, I'll most likely be buying the 4600 motor shortly... Oh well, My stupid mistake in buying the 'fastest' motor from the get go...:007:

I guess I'll have to find a 'lightweight' 2-3lb car for the 7700 to go in now... Maybe a light weight land rocket of a road car or somthing :)




Basically what I want, is for the thing to be almost undriveable because it has so much power... I want it to be stupid fast, wheely on command and be a challenge to drive because it has so much power........

Maybe the Jato tires are different, but most tires would balloon huge on a 12 cell 7700kv setup..... at any gearing. Something still doesn't sound right. Even the 4600 on 12 cells would be very very fast.

But you do know that going faster than a Jato 3.3... 65mph... isn't that easy. If that's what you are comparing your truck's performance on, then I can understand it seeming "slow" to you, since it's not a "proper" setup. Get it right and it will be fast.

I would suggest getting a good 4s lipo to go with a 4600MM if you are serious about besting a Jato 3.3.

Yea...65mph is pretty difficult without the right stuff. I might even suggest throwing a Lenher 1940 in there and running it on 4S. That should get you the 65mph no problem.

Holy cow! A 1940 in a Jato? I would think a 1920 or 1930 would be plenty. Then again, it would certainly do the job! :)

He wanted something uncontrollable :D

Or...maybe a 3080 on 12S LOL... That'd turn a SuperMaxx driveline into tossed salad at 1/4 throttle.

PS. A 3080 is one of the largest lehner motors available...It has something like 1100kv lol...

Did you program the esc to the controller?
Even if the epa is 100% don't mean you getting 100%. What if you go 125?

does it matter to an esc if you have epa set at 100% compared to 125%? I have never thought of this.. just wondering I looked my radio is on 100% now.. would it make a differance to set it at 125% and reprogram the esc ?lmk
phil

I have to say that putting a 7700 Mamba motor in a Jato, even if it's a 1/10 nitro car, is an impulsive attempt for hi speeds.

First, the Jatos are quite heavy( in comparison to a T4) due to the metal chassis the components are sitting on.

Secondly, some of the GP3300 batts are of low quality and they have a very high internal resistance which might deteriorate the performance of the motor.

Thirdly, the Mamba Max motor's diameter, though the cans are 540 size, is not of the same size as the other real 540 sized motors such as the Lehner 1920 and the Hacker B50( meaning less torque). Not to mention that the KV is very high even when using a 7.2V pack. You are almost near 60000rpm, which is not good for the motor's effeciency and that is the reason behind the high temp of the motor.

Fourthly, GP3300 packs, the good ones, can give around 35amps of discharge which is veeeeery low for an amp hungry motor. The 7700 can easily suck 90amps out of your batts which they can't afford.

To provide a good amp feeding to the motor, I humbly suggest high discharge rated, high quality lipo packs.

Team Orion has the very good 4700mah pack with loads of power.

Even better, is the TrakPower lipo sold by FlightPower.

Both of those packs come in hard cases with very good numbers of amp discharging and run time.

Make sure forward and reverse are set to 100% or more. If the reverse was set to, say, 25%, the ESC might think neutral is somewhere between neutral and full throttle and may not program right.

This thread is really mixed up:

First of all a 7700 on any fully charged 7.2 volt battery will make the tires balloon out of control when lifted in the air. It doesn't take that much power to do so, just a lot of rpm. Unless your EPA is not set correctly, you must have a mislabled motor.

2. High kv motors do not have less torque than lower kv motors. Torque is a function of amps which are mostly limited by the battery.

3. The fastest setup would be the 4600 on 4s lipo and U-bec. You will easily be able to beat a stock jato with this setup. Even the 5700 on 3s will be able to beat a jato, though it might overheat.

4. The 4600 on 4s is most likely faster than a 7700 on 3s despite the rpm difference.

Do you have any kind of limiter on the radio to?
I think you should call castle. It don't sound like you got a 7700 or
it is running like it should.

That's why I asked if hte tires would balloon... trying to tell if its' slow because it's way overgeared, or if it's just not hitting a descent rpm. Yes, the tries should balloon way up on 7.2v and they should about come off the rims on 14V

So something ain't right.

If the esc is programmed with the radio at 100%, it won't matter if you set it to 125% and re-program it. It should be exactly the same.

Just check the leds on the esc as see if it's hitting full throttle... shoudl be a (green?) led light up at full throttle.

Yup, solid green indicates full throttle.

Sleeb

Its easily possible the truck was so overgeared the ESC smoked the high end FETs and will no longer reach over 1/2 throttle roughly. Any motor would balloon the tires, a 19t would. I would bet the batteries are poor quality for the application, which adds to the problem.

Forget about it being "mislabelled" thats not something that happened if you bought it new.

It's happened on other brands...Neu motors for instance recently had a couple mislabelled motors...said 2.5 turns on the wiring but the label said 3.5 turns for instance

pinolelst

where people work, mistakes are made..

How is your GP3300 pack configured? is it inline or side by side? if they are inline, are you sure they are soldered?

Serum, here's the answer to your question:
http://www.rc-monster.com/forum/show...59&postcount=5

thanks Metal.

That doesn't explain.. (the side by side thing)

Side by side packs. He said it.

Here's an easy test:

Attach a voltmeter to the battery and run the car in the air to see how much the voltage drops.

Yup, tried the calibration a couple times. I'm using the stock traxxas radio, so I don't think it has EPA...

I'm not having any heat problems with the motor. It was barely warm to the touch after 15 minutes running...


I was actually thinking of doing that today... I'll probably do it tomorow...



For whoever asked... The tires barely baloon on 7.2v...


I think I'm just going to go buy a damn 460 and spend a couple hundred $$$ on some decent lipos.. :(

This get's more weird... barely warm after 15mins???? Hmmm something doesn't add up?

I see you are canadian. Maybe its set for km/h not mph, eh? :005:

HEY! Watch yourself buddy! :028: :031: ;)

Sylvester, you've posted it twice..:)

Each time with different spelling :005:

He just wanted to make sure he got his point across! :027:

Hmm I only see one :D

Just seein if you were on your toes....eh. :027:

I guess eh.. Oh pick on the canadians.. some day we may reach half of the american population.. than you will see!! Muahahha - LOL.