RC-Monster Forums - Successful 5S LIPO run on Mamba Max

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- - Successful 5S LIPO run on Mamba Max (https://www.rc-monster.com/forum/showthread.php?t=4499)

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

Quote:

Originally Posted by captain harlock

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?

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.

Quote:

Originally Posted by captain harlock

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

Quote:

Originally Posted by Finnster

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.

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.

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.

Are the lipos cold? That has a big effect on lipo performance. But still, I wouldn't think an 8000mah pack would hit 3v per cell... what motor is this on?

Lipos were room temp but it wasn't the problem. After reprogramming the MM to "No - Cutoff" I had no problems and it ran perfectly.
Here is my system.

off topic: can I download the videos from utube or google to my hard drive so I don't have to be online to view them?

Can't see much point trying 6s. You'd need a UBEC and cut-off/LVC, plus it would run really warm, more worth while going for the Quark or MGM.

I guess on 5s you would need a UBEC to?

Quote:

Originally Posted by glassdoctor

off topic: can I download the videos from utube or google to my hard drive so I don't have to be online to view them?

You can if you have FireFox and install the VideoDownloader plugin.

Yeah.. with 4S a ubec is wise.