Successful 5S LIPO run on Mamba Max
 

Serendipidously I got my 5S (2+3S) lipos yesterday and got them charged and took my Evo out to lunch today to do a run. One word...WOW!

This is the 1st lipo pack if used, previously the highest I ran it was 16 GP3700s. Damn, lipos are really nice. The truck is truely wheelie on demand, even in loose dirt/sand.

Quick specs:

Mamba Max w/ 25mm 5v fan, 8XL, Rx pack, 5s2p 8000mah TrueRC cells. Emaxx tranny, 16/51 gearing, stock everything else (inc tires.) RTR weight of 5.0 kg.

Had the radar run out as well and did some speed runs on a long paved walkway after I drove in thru a sandy dirt track for ~10min. Did several back to back runs. Speeds were repeatedly (7-8x) 48 mph, with one run of 49.

The thing sounds like and absolute beast. Nitro people talk about the sound as a big reason to enjoy nitro... this thing sounded fierce and frightening as well at WOT. Like Satan's P'd off blender drawing your hand in, looking to liquify it. The spool up is amazing.

I was constantly checking temps. Even after all my speed runs the ESC was at 124, caps were @ 141 and the motor was 150. Ambient temps is ~68 (really nice day. :) ) I did run thru the grass for a while (~3-4min @ WOT) and the temps did climb, the motor got to 176 while the ESC went to 135, and the caps were ~146.

I normally run at a 15/51 gearing, so a little overheating was expected. My best speeds to date (at least repeatable, not all time best) was 44mph for 16 cells @16/51. I did do that once w/ 15 cells, but haven't had a chance to repeat it. The lipos are noticebly faster, punchier and vicious.

For Daf's sake,

Tthe MMax is still on factory settings and is using the elec brake. I have the brake turned down to 10% IIRC, and its still a bit harsh. Wants to just front flip w/ more than a feather touch on any higher setting. Consequently braking was fairly light, else flippies.

I've had good luck with reducing motor temps by setting the start power to "high". Might want to give that a shot.

But yea, LiPo's are just flat out vicious. They make cells seem kinda silly! :)

Sleebus

Woah, this is real good. To think how cheap the MM ESC is to!

So can it be pushed to 6s?

I'm thinking "yes": http://www.rc-monster.com/forum/showthread.php?t=4497 :)

As long as you read the fine print. That's 6s LI-ION, not lipo. ;)

But it IS more than 5s Lipo. Not to mention M1 cells since they are the only Li_ion I know of with 3.3v nominal voltage. Normally, they have 3.6 or 3.7v nominal voltage.

If the Mambamax can take 6s I will be kicking myself laughing... I mean. What a bargain! 5s is just insane enough for what it can give.

I will buy another one for my E-Maxx to replace the 9920 if that's the case, get some nice fans on it to.

I don't think I would do 6S, full charged would be 25.2V, and the caps are 25V rated.

Not that I think I would just die or go up in flames, but it would be asking alot if it. You'd be looking at a decreased lifespan prolly, but... if someone wants to try... :)

I agree with Finnster; even though manufacturers factor in a safety margin when rating components, running them so close to their max ratings will only shorten their life. Besides, the only hint for voltage rating we have is the rating on the caps. Those are electrolytic caps and are typically rated at 1v, 10v, 25v, 35v, 50v, and so on. Just because they are rated for 25v doesn't mean the rest of the components are.

Also keep in mind that the potential to draw more current than the rated 100A is MUCH easier with higher voltage.

Personally, 5s is pushing it. Just the fact that the CC rep said not to use the ESC as a brake at that voltage tells me that we are approaching the usable limit.

Yeah, the power output @ 5S is tremendous, and this is with just a Feigao motor. I think this setup is really close to what the ESC can handle thermally, and may even be a bit much if you just wanted to drive thru grass, or other extremely challenging driving. I don't really do that, so it works for me. A Neu would help the situation. Its actually asking alot from the chassis as well I think as well to some degree. :)

What this ESC is doing is really remarkable, and is making even more excited for the monster maxx. I really hope to see a 6-8s controller, and the hints that Shaun P drops make it seem this is not unreasonable. If you are looking to go above this (and even up to this) you need to be careful and really watch your setup. It's not for everybody, but I am smiling. :017:

Now, I believe Shculze might be crying on their mother's shoulder:

A Schulze controller: " MAMA..MAMA..Maba Max is kicking my *ss..waaaaahahaha..".

Schulze's mother: " See! I told you that you've to be nice to people. Shame on you Schulze my dear".

YouTube
Google Vid

I made another quick vid of my brushless Revo in action. This time I have it running on 5S lipo, and its literally wheelies on demand. Its so much more powerful than on 14 cells. I've radared it @ 48 reliably w/ stock tires. Put new mashers on for the vid and they were balloning so bad I couldn't ever get to top speed, they just turn to pancakes. 35-40 mph is about the limit for mashers, so they should be Ok w/ a Hv 6.5
Keyword is throttle control, I'd rather have my finger holding me back than the motor. Enjoy!


Specs:

Mamba Max Esc
Feigao 8XL motor
Emaxx tranny, 1st gear removed
custom batt trays and rollbar
17mm Maxximizer beadlocks w/ Maxx Mashers
Rx Pack


Youtube


Google Vid

Thanks for posting up those vids. Did you do any special proramming of the Mamba Max? I've tried out different battery combinations myself. My LST2 conversion does fine with 4s 8000mah and also with 5s 4000mah. However it is not too happy with 5s 8000mah. With the 5s 8Ah it will run only if I ease the throttle up but once it reaches half throttle it shuts down. I haven't quite figured that one out yet.

dude, thats crazy!:026:

Finnster,
How did you measure the top speed? My single BL Maxx did 46mph on radar and yours seems to be quite a bit faster than mine. I think if you tried to get top speed on that street in the vid that is not going to be long enough. I think it looks faster than 48mph but that could just be me.

i had the same issues... if you get the g2r it will become much more stable... longer chassis + lower cg = more throttle!!!!

Doesn't look faster to me Johnny..?

Cool thing though, makes me want to drop my MM on my 8XL as well..

I tested the 7XL on 5S lipo.. That's pretty amazing fast..

Serum, does your Mamba Max dude coggs at launching?

I did the top speed testing at the initial 5s run a couple weeks ago. I basically had a very long pathway in a park to do it. I ran the car repeatedly in both directions and measured with my radar gun. It was a very consistant 48 (once of 49 ;) .)

I didn't do any radaring in the vid, it gets a bit tough to do, and I have the truck coming right at me. No one wants to see that in a vid :) (unless I managed to run into myself, that could be entertaining.) The initial speed run was with the stock tires, but I switched to 17mm beadlocks with mashers. I actually couldn't get upto fullspeed as the tires would turn into 10" pancakes and swerve badly out of control, that or the front end would pick up. Most of the shots in the vid I let off the throttle as soon as the front end comes up or the wheels balloon too much and it starts getting unstable. This usually occured if I went full throttle, so most of the vid was partial throttle or it would just go flying onto its back.

I think the 48 was a very fair speed, tho I think I could break 50 with lightweight hi-speed tires and a modest diet. All I know is its quite fast enough. :018:

Cogging? what's that..

this movie was before i programmed the controller to the esc. on this movie it was smoother backwards than going forward. after programming it was like this in both directions

this is the micro-movie

And yes, i am winning the ugliest tire contest with this vehicle.. I know..

Hmm that is odd. My MMax is actually stock from the box. My comp is having a little meltdown w/ the usbs and I've never had a chance to program it. I could do some manually, but.. been having too much fun to bother.

Besides myself and Cart123, you are the only other I've heard to run 5S yet, so its very much R&D at this point. Did you but in a voltage cutoff? My only thought is that perhaps with your large truck and big 1515 Neu motor you end up pulling a lot more amps and lose voltage below the cutoff. Or its just too much for the esc... I would think the 8Ah batts would be better as far as voltage drop, but maybe they are lower C batts vs the 4000s and don't handle the lg load as well. Perhaps its even a bum cell in the 8Ah pack... :032:

Cart123 actually ran more voltage (6S M1 cells) but really only had thermal issues IIRC, so I don't know if its raw voltage. We're playing on the edge of the edge w/ the equipment, so there are no guarantees. Very nice conversion tho, drives great.

No, I'm not talking about the movie. I'm talking about whatever vehicle you're using the mambamax with.

Here's the question again:

Some people says that their rigs stutter when they make them accelerate- with the MambaMax being used.
Did you experience the same thing, Serum?

No, but mine isn't a good refference yet.

I am doing some indoor driving with 8 cells and a 1400kv 6 poler.

Now that you describe it, I have experienced that w/ mine before, irregardless of cell count tho. What its like is as if the brake is suddenly applied for a fraction of a second. The first time it happened i thought I had blown and seized the diffs. It only did it to me when the truck was far away. I thought it was a reception problem, and was one of the reasons I switched from Am to FM and to the Rx pack from Ubec.

It pretty much went away after that, but did happen but once. hmm....

Serum, whats wrong with the Badlands? I kinda like em...

They are HPI GT tires actually. badlands are rather cool, and probably a ton lighter..

Thank you for posting this. I have been kicking around the idea of puting the MM in a 1/8 buggy on 5s and wasnt sure if I wanted to trust the MM to be stable at 5s. From what you are seeing it sure looks like it will be fine in a smaller lighter buggy vs the Revo. You have convinced me.

BTW: You arent kidding about that thing having some kick either. It looked like it was literally jumping off of the ground without a ramp when you punched it. Nice work.

Wow, that video made me glad I decided to sell my 9920 in lieu of a MM for my 8XL.

I'm having that issue, captain. It's not a voltage issue, though. It cogs whether I use 4s or 6s. Once I get it going it is fine. I'd say that it happens about 25% of the time when accelerating from a standstill. I tried changing the start power on the MM from low to high, but that didn't help. When I hold the truck in the air and then accelerate, it never cogs.

Is any one going to try 6s lipo? I would be curious about it.

Someone already tried it, and it went fine with a fan. You can look up the thread a few days ago.

haha, the guy two posts above, tho they were the 3.3V A123 cells.:005:

I couldn't recommend going 6S, 5S is already pushing it. I think if I did alot of WOT grass drving it would thermal even with the fan. 6s would have to be a pretty high turn motor to keep the amp draw down to even consider it, even then its over the caps rating of 25V.

I drive in the street or on dirt just bashing, so it works for me. For long term use I think I will prob go to a MMMax for a larger margin of safety, but it works really well for now.

Yeah, a fully charged regular 6s pack exceeds the working voltage rating of the three caps outside the ESC. Who knows what the internal parts are rated for...

Another thing is that the built in cutoff won't go up to 18V

Thanks for the input - It is now running with 5s 8000mah:027: I suspect one of two things. I am running a 2s and 3s in series. The 3s is one of the newer Maxamps "HV" packs. The 2s was a MaxAmps pre-HV pack. It is now working after replacing the old pack with an HV pack. It could be that the older pack was not up to the task or that I just forgot to charge the older cell before hooking it up:007: Most likely the latter. I hope to get vids up of mine with the 5S soon.

Ah hah!

:)

It wasn't the batteries after all. I tried running with two new HV Maxamps freshly charged packs this morning and no go. I had programmed the MM manually for 15.2V low voltage cut-off. You said you were running defualt settings so I re-programmed the LVC to the default "No Cutoff". It's alive!:dft002: The only problem I have now is needing a new rear shock tower after having the truck wheelie onto its lid and slide down the asphalt 20 ft!

I'm not sure why the LVC is kicking in. Voltage from the freshly charged packs is a little over 20V. I'm wondering if the firmware was not written to account for manual programming above 3s.