Slo-V Flyer

I'm sure the 1000 watts rating is meant for the 3s lipo 11.1v setup where the MM ESC can pump out 100 amps from the lipos and get 1000 watts (~11v x 100 amps = 1100 watts).

RURC

Not really the 1000 watt rating is meant for the motor not as a rating for the esc. Your math is correct but your premise is faulty. To figure wattage on the esc you have to correct math. But at 11.1v the amperage needed to run the motor at 100 watts is 90 amps. Well below the 100 amp rating of the esc. The esc wattage is dependent on the voltage at 100 amps. Example 14.8v will yield 1480 watts then 18.5v you get 1850 watts, and so on and so on.

The MM esc will easily run the 139 amps surge without a problem. But the nixx batteries, again, will not supply the power. Thus cogging. This is a result of cogging not caused by the MM, it is a result of the drop in control voltage. Now lets be serious a 1/10 car is not going to cause the motor to want to generate 1000 watts of power. But the Novak can not over draw the batteries in any situation under acceleration and the MM at just 500 watts (1/2 power) it will draw 70 amps. This is still more than the nixx can provide.

mbeatle

You keep pushing the fact that nixx batteries can't supply the amps to drive the motor to its maximum, but that doesn't mean cogging is the result. I'm able to run 1900 mah batteries on my MM5700 without a problem and without cogging. I only notice problems when the pack falls off its cliff, but by then the fun meter has been pegged anyway.

RURC

I am simply pointing out ONE of the many things that can cause cogging as a symptom. And unless you know of a way to change physics they can't provide the power to run to the MAXIMUM.

mbeatle

Nobody said nimh or nicd batteries were the way to get the most out of a brushless motor, at least not in this thread. I think you took my comments about IB4200s being more than adequate to eliminate cogging the wrong way.

Let's get this thread back onto its tracks. The OP referenced people not being able to harness the power that brushless gave them. I'm one of those people who can't reign it in Wheelies are really not a huge issue for me, at least not as much as I thought they would be, but I am contemplating swapping out my RPM bumper for an aluminum one, or zip tieing some ballast to it so that I don't have such gross understeer.

I also have a problem controlling the car when it gets close to 30 mph. It wants to flip like crazy, and seems a bit unstable, even though I have the front wheels toed in.

BanditMonster

Majority of brushless systems require a li-po to properly supply the amps, not just a CM36 motor. However some people don't realize the motor isn't constantly pulling it's maximum amps, or even a 100 amps continuous once it reaches top end rpms, it pulls no where near that much. Some systems are powerful to where certain nixx batteries can not deliver the juice (amps) needed to make a quick acceleration. Owning the Mamba AND the Novak, both systems _can_ rely on nixx batteries such as the IB4200's to get them to good speed, but it won't let those 2 systems recieve the required amps for the systems maximum rated amps even with IB4200's udner a stressful situation. However, Once either of these systems start to reach their top rpm's, their need for amps is slowly decreased, and a much lower amp draw is needed to continue those speeds. It's all just a matter of how many amps a battery can provide to quickly get a motor to it's higher rpm's. Rest assured that IB4200's/DTX 3800's will surely let the systems (Mamba included) reach their top speeds, but just not as fast as li-po's. Weight itself is just a big factor.

Systems pull the most amps when they are going against a force, or during the acceleration stages of a run. They pull the least when they reach near their top-end rpm's. They won't be pulling anywhere near 100 amps continuous, regardless of the watt rating, unless they are being ran in a _much_ heavier model which puts more stress on the system, hence requiring more amps. A motor only asks for amps when it NEEDS the amps. Which leaves me with a question:

1) If a motor/system doesn't need to pull more amps than what it is given to work with, doesn't that make it the more efficient system?

2) If _another_ motor/system NEEDS to pull MORE amps for the SAME situation...wouldn't that make it the system which had a more troubling time to do what the first system did, hence making it the less efficient system?

You can have a battery that supplies a 1000 amps continuous, but the fact the Mamba is a sensorless system, will always leave it open to the possiblity for it to cog now and then. It's just a simple understanding that people have taken to another level of complication for almost no reason. The rotor in a sensorless system needs to be spinning in order for the ESC to figure out it's current position, to provide voltage to the correct polarity, it has nothing to do with how many amps a battery can provide. It's almost like saying, "with enough amps provided to the motor, the ESC will magically know where the rotor is", which is just ridiculous. A strong battery can only minimize the cogging... not eliminate it all together, atleast in terms of accelerating.

Access

It actually pulls the most amps with braking (not when accelerating).
The 'cogging' thing is b'cos the word is often mis-used. The most common type of problem often cited as 'cogging' has nothing to do with sensored/sensorless motors at all. Basically what happens is this -- if you have a battery that is 7.2V and a receiver that works down to 4V, a linear BEC with a dropout of 0.5V, when you pull the throttle and accelerate hard (or brake hard) the battery voltage falls to less than 4.5V. The BEC voltage falls below 4V, the receiver dies, and the ESC just glitches or goes into failsafe mode. The car jerks forward and stops. Eventually the battery voltage starts to rise again, receiver comes up again, sees full throttle, and the car jerks forward again, battery voltage falls, receiver drops out, repeat as long as you hold down the throttle.
Real 'cogging' comes from a sensorless ESC not being able to start the motor spinning in a controlled fashion, but that is much rarer than the above. This is why 'cogging' often appears to be solved with a LiPo or better battery (or in some cases even a larger capacitor in parallel with the battery). With the mamba, you won't see true 'cogging' past 60rpm, if you see it past that, you are seeing something else.

BanditMonster

Well Im glad someone cleared that up...

I guess I meant that "stuttering" and confused it with cogging? :S I always thought cogging was the cause from a sensorless design, I guess it can be refered to as "stuttering" considering it DOES exist.

Yea, braking/accelerating eat the most amps no doubt.

RURC

I really may have taken it the wrong way, but you did say it was more than adequate and they are clearly not. I can tell you that if I take the same car and do nothing but change the batteries to a good set of lipo's the "cogging" issue leaves. So it dose effect the performance of the Mamba Max esc. When you monitor the voltage on IB4200's and in the same car you can watch the voltage drop below 5 volts many times. This is the point where problems start to happen with the receiver and 'cogging' starts. This is why this happens on initial start and not once the car starts to roll smoothly. Remember braking uses the most current of all but this is done under control of the processor on the esc so cogging under braking dose not happen. The initial starting is where the demands are the highest before the programming takes over to control the phasing. Depending on your gearing and tires and grip and so on and so on in a 1/10 car you can exceed 40 amps (the limit of voltage stability on IB4200's) without too much difficulty. You have then entered the area of too low of voltage for the system to operate.

If you want ballast gat some stick on wheel weights for tires and keep the RPM bumper. If you replace it you WILL bend it on impact with anything.

Why dont you get a lower kv motor if the speed is too much for the car. There are hundreds of options to go with.

RURC

What do you think I have been saying for the past several posts. Talk about needing it spoon feed.

Braking can draw 4 times the current of acceleration. When we were testing the Mamba 25 it was common to see draws of 125 amps and more under braking in Mini T's. We would see 33 amps under acceleration. These were momentary draws but they still effect the voltage stability. Now normal running would draw 9 to 14 amps.

BanditMonster

Let me jsut edit my whole post, you seemed to have missed a very simple line.

"Yea, braking/accelerating eat the most amps no doubt."

"What do you think I have been saying for the past several posts. Talk about needing it spoon feed."

I kinda understood that the FIRST time I read it from Access, thank you very much.

I was talking about stuttering/cogging in my earlier post, not amps draw from braking.

mbeatle

So much for getting this thread back on track. It seems people only want to talk about batteries now. My brief mention of cogging ruining a testing session wasn't cogging at all - it was a problem with a loose wire between the motor and ESC. Cutting off the factory bullet connectors and replacing them with sermos connectors solved the problem. It was a mistake to even mention cogging. As for the lack of punch off the line, I later found that the punch control was set to 40% which does just this. Cutting it to zero makes for a wheelie machine if I choose to hammer the throttle. I prefer to let my finger do the traction control.

Can anyone comment on adding ballast to the front end or replacing some parts such as the bumper or skid plate with aluminum? I'm enamored with RPM's front bumper, but I think an aluminum skid plate (very low on the truck) would help even out the weight balance, even if it means adding weight to the truck. With a brushless motor and hardcore bashing as a goal, I think these would be good additions.

BanditMonster

well just remember, a hard enough bash can cause the aluminium to bend, where as the plastic will simply flex.

however if you are looking to balance the front with the rear, I guess you can purchase the aluminum one, it would weigh more than the plastic one, but it wouldn't be much of a difference.

maxn

In a previous life I used to use fishing weights - small lead weights - to adjust the corner weights on my racers.

Easy to secure with a dab of silicone and if ever they need removing they are easy to cut/peal out.

I would shy away from an alloy bumper - too rigid - all it wil do is pass 100% of the impact to the mounting points rather than absorb a percentage.....

morespeed

scared to ask now, might get beatup in here.. i'm not a boxer just a driver.
i asked about the novak and MM and yes it is the CM36 5700.
I was just wondering between the two because i have 2 novak's system and they run around
110 degrees only with a 6 cell ni md. i run them in a losi xxxt, rustler and a HPI MT.
I just got the MM 5700 and a 3S li po , before i try and figure out WHICH TRUCK to run it.
just wanted to know the do's and don't on the battery setup first. cause i have the GP 3300
and a fusion V2 3491 batteries. i'd rather not smoke them.

I'm not a basher but i do have a large track i run on that i've build in my yard. it's 100' x 200'
1 long straight and lot's of sweeping turns. large enough that i run my ofna lx, hpi 18ss, and
cen genesis .46 on.

Question is, did i make a mistake buying the MM5700? because all i'm reading now is how this more either runs hot or smoke's batteries.
oh, it's a 3s 4000 or 5000 max amp battery 100amps. should i have gone with the 2s instead because of my track size. the losi xxxt and 5800 novak already hang's with a nitro REVO.

mbeatle

In my two hard bashings I've had with the curb I've broken:

1 - shock tower, skid plate, bulkhead
2 - shock tower, skid plate, bulkhead, chassis

The FLM aluminum bulkhead looks nice and extends the wheelbase by .200. I'm not sure if that's inches or some type of metric, but that would help handling as well as durability, no? I've seen people zip tie deep sockets onto the front bumper as well. I suppose that'd be a free test to see how additional weight makes the truck handle.

RURC

banditmonster-
I was trying to give you a load range of what happens under the separate sections of acceleration, braking, and running. All I am trying to give is information. About going on to the amp draws my intent was to show what these loads do and how the effect the system. I have said what Access said about 500 times on this forum not to mention on this thread. My apologies for getting tired of repeating my self, I really should not let it get to me but sometimes it dose.

morespeed=
I tried to give you comparative information on the 2, but I did not hit temp. The CM36xx motors are fine to 200 degrees F. The reason you are hearing about fried batteries is because if you are not careful any brushless out except for the Novak and LRP can cause the nixx batteries to get too hot thus ruining the pack. With your 3 cell lipo you should not ever see any problems. You can deliver the needed current and keep the voltage right. On your batteries if you have the 4000 it is a 20C pack and will provide 80 amps of current with less than .5 volt drop continuous with 30C sustained for like 10 seconds. The 5000 is the same except the the current is 100 amps with 150 sustained.

RURC

I thought I mentioned that you can use adhesive backed tire weights. These work great and are available at any tire place. I would really keep the plastic bumper. I cant tell you haw many times it has saved me on my converted Jato. Which BTW it converts to the best handling truck I have ever ran. As a nitro it was stodgy and unrefined. But as an electric it is smooth and clean. I really like it now.

morespeed

thanks RURC,
BUY THE WAY, IT IS THE 3S 5000 FROM MAX AMPS RATED AT 100A

RURC

Let me tell you that if you have the space the 10,000 mAh packs are just amazing. I use them in all my cars where they will fit. They are a little larger than the 5000 packs. Just a few mm wider and longer but you can run for what seems like hours on one. In my 1/8 scale cars they run for over an hour. I have no idea how long they last in my 1/10 cars I get tired of running before they run down at all.

lee172

10,000 mah? thats crazy! i'd be out there all day with my CC-01 (with sport tune motor!)

morespeed

good grief RURC
i'm already up to my neck in RC'S. my room is like a hobby shop now.
it takes my me all day already to just charge batteries. i have nitro trucks, electrics trucks,
and electric planes and helicopter. everyday i have problems trying to figure out which i want to play with for the day. today was plane day, sunday will be race track day. i hope.

One battery all day does sound good, money, money.....
i may need a new hobby, 7 planes, 1 helicopter, 7 trucks. uh,
anyone else this deep yet?

thanks RURC, and everyone else your info helps alot.

RURC

List of cars currently in the back of my suv...

Schumacher- Havok, mi2, mi3,2x GTRe
Associated- 2 x B4, T4
RD Logics- SHO Pro
Traxxas- Jato
Ofna- 7.5
Keyosho- 2x Mini Inferno, 777

All are brushless cars that are blinding fast and reliable. Mostly Mamba Max esc's. 1 Quark, 1 Hacker, 1 BK Warrior, 1 Schulze
Various motors from LMT, Hacker, Krontronik, Castle, Aon, Nemesis and Neu.

The rest are at the work shop ranging from a 1/4 Leadenbacher to Mini T's (6) all also various brushless systems. Also 2 planes, 1 Groupner Hydroplane (land, water, air) 3 Boats, and 2 choppers.

I am sick and my wife has one rule no household money can be spent on this hobby. So I build cars for clients all around the world and I do testing for manufacturers and prototype building.

Dose this make me as sick as you? You do have more planes. But I got you beat on 1:1 prototype planes, that is my normal job. We did the Raptor and the the Comanche before it was canceled.

morespeed

RURC.
you got me beat, thought i would at least try though. but there is one thing about us for sure that is equal.....

WE HAVE AN RC PROBLEM AND NEED HELP.

lee172

that sounds risky leaving all that stuff in your SUV [X(]