Mamba Max in a Savage?
 

Hi guys, I'm looking to purchase a new speed controller for my BL Savage to replace my 9920 (not smooth, non existant tech support, only wrapped in heatshrink, etc), as some of you are already aware :) I'm thinking of the Quark 125, but it sounds like it thermals easy, other than that a good esc.

Then someone mentioned to me his testing one in a Twin Force, and it might work in my Savage as well (weighs 5.6KG or 12.5lb RTR with 12 cells). Which got me thinking, a couple of people have used them in 1/8 buggies..which are lighter than trucks, but have heavy drivetrains, so why not? I'd like to get some other peoples opinion on this, if you think it'll work or just thermal after 5 mins hard running. Espically from any of the guys using them in 1/8's or that sort of thing.

The rest of my setup will be, 540C 8XL motor, 14 cells GP3700 (mostly 14), and of course an external UBEC. Geared for around 40mph on 14 cells. My 9920 works fine but does get hot, its not thermalled yet though. Without fans. I have been given the green light by Mr Palmer= for the extra voltage btw upto 16 cells.

Cheers.

Wow, I was told not to do it with a 7XL and 12 cells, by MR Palmer. Must be they think it can do it now.

You got a green light for the mamba-maxx up to 16 cells?! how about 5S?

I'm also intereseted......my quark is sucking the big aXX!!!

I just emailed Shawn too, he told me it was on your own risk, it is good to go to 4S though.

Just my $0.02: I wouldn't do 5s. At full charge, 5s=21v. The caps alone on it are rated for 25v - who knows what the rest of the components are rated for. That's a bit close to the ratings. It should work as manufacturers figure in some tolerance levels, but you might decrease the life expectancy.

5S is pushing it too much IMO, 4S is tested and proved to work.

The 7xl draws more amps, I beleive the spec sheet is ~103A or so, too much for a 100A ESC. The 8xl draws ~10A below that, so its ok. A 9xl would be even safer.

I too read somewhere a while back that the MM could do 16, but that is getting really high. The lg caps are 25V, so... Personally I've ran mine /w an 8xl on 15 GP3700 cells and it did great, and did mid 40s. This is only a rare occation I found the 14 cells speed more than enough.

Running on 14 well used GP3300 packs The revo does a touch under 40, so 40 in your heavier savage may not be possible on only 14 cells, tho fresher batts may do it. Dunno. The ESC was fine, but the motor starts getting pretty warm, over 150F, so that's more of the stumbling block.

You will need a fan tho. The esc quickly got upto 140-150F on a single pack of the 14 cells w/o fan. On even a small 25mm fan, temps stayed below 130, even after 4 pairs of packs and hard bashing.

Cliffs:

Yeah w/ the 8xl, but care has to be taken as its pushing the limits of the esc.

Bullocks.

the 7XL is okay in a buggy on a 100A controller.

The currents you are talking about are vehicle and gearing dependant, and it are peaks.

a 100A esc can handle higher peaks than the 100A as well.

Just to clarify a bit, I was given the green light for extra voltage when I was discussing using one in my RC10GT with him, and under the conditions that I inform him of any odd things or problems they might have missed in testing, and he'll cover the warranty as long as I explain the exact circumstances to him if anything bad happens.

Finnster, am I reading that right, your using a MambaMax in your Revo on 14-15 cells with an 8XL? And 130F running with simply a small fan on it? If thats the case I'm ordering one asap, sod the Quark.

Well true, but the point I was trying to make is that the 7xl will draw more current, and we are talking about a heavy Savage and not a light buggy. It may work, but IMO given the app, its too hot a motor.

I would think you would really begin to fight heat issues with the esc which already requires a fan to run a higher turn motor in a lighter truck. Who really knows, AFAIK no one has tried it. Is it worth the $ to risk it? I can't recc it.


EDIT: N/M, my reading was off.. I would think a 7xl on a MM in a buggy may work. May still need a fan tho.

@RTS:

Most of the driving has been on 14 cells, 15 was done as an experiment on a speed run, but the tranny case was damaged during (the bearing hole for output shaft got loose and wobbly) and I haven't got it fixed yet. Outside was ~68F and the esc was ~115, but only ran ~10-15min before breakage.

I used a 40mm and now a 25mm and the temps have stayed low on me. I was using the 40mm fan driving hard in 80-90F weather in Aug and temps stayed low. Gen no higher than 125F, usually less, so I put on a smaller 25mm fan. Temps went up ~10F, but a still very safe range. Caps got to ~135F as a fan no longer blows on them. I'm certainly satisfied with the MM for mine, but YMMV.

I use the 7XL on 5S lipo, which is taking quite some juice on it. (120A-130A) this is still with a relative tall geared maxx, and this is with the warrior 9920, which isn't getting too hot either. again, the 7XL is only taking it on peaks. On 14 cells it's more than fine. It gets hot. But not too hot.

Using the mamba maxx on 14 cells isn't something i would recommend either to a user, and you have it in your signature.. LOL

:P


I like pushing the envelope, :) that's why I say YMMV (your milage may vary.) Works for me, but much of this is untested, unsupported so evreyone is a pioneer. Reminds me of the early days of overclocking cpus and how much fun that was.

I'd love to see some more people push it and see what it can do, but I'm quite content with my setup. The only bother I have is motor heat, and it may not be so bad as I'm just very cautious when it comes to heat. A Neu would go great.

I'm trying to avoid smoke coming out hence staying with the 8XL :)

Them temps are very impressive, can't be anymore than what my 9920 gets at the moment with my 9XL. How much does your Revo weigh?

I'm aware I'm riding the limits of the controller..but I think its a safe gamble based on input from your and other people. Never hurts to push the limits a little does it. Well till it actually blows and your $140 out of pocket! :D

Maybe it's your gearing.. because I'm using the 9920 on the LST which is heavier I run on 12 and 18 cells with no problems..... and a 7XL... But maybe the 8XL or 9XL if you wanna be safe....

RTR it weighs 5.2Kg w/ 14 cells

Brushless LST 18 Cells RTR, 7XL and 9920, 2 40mmx40mm fans... 7.08KG(15.61Lbs)

Is that Mamba Maxx really rated at 100A continuous?....

That's what the specs say. Some people are using them on 1/8th scale applications with XL sized motors without thermaling, so I would say yes.The actual FETs are probably rated for quite a bit more, but the circuit designers have most likely "derated" the rating somewhat to take temperature and other factors into account. Plus, if they rated it for what it could actually do, then people would still push the limits.

Their relative low temperatures are a big plus.

Wow, 7KG!! Hows that shift? Does 18 cells really make that much of a difference or does it come out a bit under powered? Guess at least you can brag about having a massive truck :D

Finnster, nice, my Savage is only 450g heavier RTR than your Revo, my setup and projected speed should end up rather similar to yours then? With mambamax, 8XL, 14 cells.

yeah.. the 18 Cells do make a big difference... I will buy a Mamba maxx controller.. and convert 2nd my Nitro LST to a brushless ... again.. I will use the 7XL, I really like this motor...

Yeah, the 7XL is a nice motor, that's the main reason why i think i will love the neu 1515 with 2200 kv as well.

I wanted to tweak it down a bit, but on 4S a 2200kv is nice.

Sorry to hijack the thread, my friends, but I have something to discuss regarding low amp controllers with hi voltage capability.

I have the Kontronik Jazz controller which can juice out 70amps surge and 55 cont. It has no heatsink, though.

Is it gonna be a BIG mistake if I use it with 8s lipos ( it can handle 10s easily) with a 1950/10 geared 24/51 in a SuperMaxx?

They say if you use a slower motor with hi voltage, your controller will suck less amps and stays a bit cooler.

So I'm thinking about using that dude in my truck and I dont even care if it blows up, since no one is really interested in it.

1950/10 is too hot. 55amps is nothing for a car. (remember, even the mamba-max controlers are for 1/10th vehicles and can do 100A continues.

but with 8s lipo the 1950/10 is still around 40000 rpm.

bottom line;

your theory is okay, the more volts the less current is needed to get a certain amount of power.

The maxximum power of the setup on 8s would be 1628watts, while a 9920 on 6S can deliver 2200 watts.

if you want to go with that controller i would look into a 700-750kv motor.

with the current setup you are planning on gearing it for 56 mph.

I was just thinking on using it to see if it can do me any good.
Right now the 18.149 controller is in the truck. I'll be using 6s for sure. 8s is just a thought.

I would think it would be pretty close.

My Revo is a bit of a :040:, but its not too bad. The motor and batts alone are over 1.5 kg! Otherwise the conv did not add much weight. Everything other than the BL is bone stock, so there is a bit of fat to trim, but that's the next project.

That's the motor I'd like to get if I replace the 8xl. For now its working well tho.:)

Thanks for all the help guys, I have a Mamba on its way to me now to test.

Used my new temp gun today, my 9920 was hitting 160F when I was driving the car quite agressively on dirt and grass. Motor can didn't seem to go over 130F though. These felt like the typical temps I'm used to. When this setup is in its next truck I'll make sure theres a fan installed over the warrior.

the fan on the 9920 will make a huge improvement, should stay very cool.

Got my Mamba today! Along with a 540C-8XL and new UBEC. I'm really impressed by this setup, my Savage had more low end torque and more top speed than before, no hint of cogging at all, low speed feels almost like driving a brushed setup its that smooth. And the USB link, I love this. No more counting beeps or watching leds to program it, just plug it into the pc.

Temps are great, without a fan, 156.1F was the highest temp on the mamba, 143F on the 8XL. When I fit a fan to the ESC tomorrow I'm hopeful that will drop at least 20-30F, then I will bump the voltage up to 14 cells. I'm hopeful this setup on 14 cells will outperform my mates MGT with 18 cells and my old 9XL/9920 setup, mostly because his MGT is like 15lb, my Savage is now a cool 12lb 3oz.

Only annoying thing, is my radio range is significantly reduced compared to the 9920. Using an airtronics MX-3 set, its not much more than 100ft. Going to solder a new ariel onto the rx tomorrow and see if that helps. Oh and its a real pain in the you know what to mount, no decent place to mount it in a Savage without having excessively long motor cables. I think a small lexan "shelf" to mount it to over the gearbox is in order.

For me, my range depends on where i mount my ubec.....

Great to hear it runs with succes rtsbasic!

The UBEC is held on to the battery power cables with a rubber band. Can't really move it further away from the reciever because the cable length. Might try seperating it from the main power cables a bit though.

Serum, I'm glad it worked too, would have been a shame to toast an ESC on its first run! :)

try flipping over the ubec or route your antenna a bit different..

The antenna comes out the reciever and straight up, using a custom mount (2 cableties :D ). I'll try moving around the ubec a bit before I next run it tomorrow. Hopefully its something simple like this thats causing the radio noise. The wiring isn't yet as tidy as with the 9920, so thats another possible cause of interference.

I have yet to test the range with my spectrum moduleand hitec eclipse pro but tomorow i will try to go somewhere i can let rip and i will be able then to really see how good the spectrum is range wise.
I would suspect thought that the mamba has been excessively tested with the spectrum dsm system.

rtsbasic what timing you using at the moment normal?

Let me know how it goes with the spectrum mate, I'm thinking of upgrading the radio anyway - the recievers been repaired that many times i've lost count.

Used the lowest timing setting on its first run, to be on the safe side. Bumped that up to "low" for its next test run tomorrow. Also changed the start power to "high". If the temps are still good I'll keep playing with the settings.

Re-did some of the wiring tonight, moved the UBEC off the powercables, made & mounted a lexan plate for the esc over the gearbox, and fitted a 40mm fan. Will snap some pics tomorrow, it don't look too bad although the shape of the esc ment it wasn't quite as tidy to mount as my 9920. I can access the USB port fine without taking it out the car though.