Mamba Max on 5s A123

[Sammus]

I've read of a few people trying it successfully. Has anyone ever had a failure?

I'm considering a buggy (HB Lightning 2) conversion running 5s1p a123 and a brand spankin' mamba max, I might do it in my mini baja too (read: purpose built dune truck - extended rustler with paddles :P) . It's currently running 4s A123 through a sidewinder (no mods, caps, ext bec or anything) and its running like a dream so I dont really have much of a reason to change it.

[Sammus]

bump. Anyone?

I've heard of people frying the max just connecting a 5s Lipo (21V full charge), never heard of anyone frying one on 4s lipo (16.8V full). So I'm kinda hoping ill be safe with 5s A123 (18V full charge) - somewhere in between :P comments welcome.

[RBMike]

I've been running 5S A123's for a couple of weeks on the MM. It has the hole modes & 2 fans & I'm using a CCBEC. All works fine with a 2Kv Medusa.

[Arct1k]

5s2pA123 is equivalent to 4s1p Lipo - This is a pretty standard setup with a modded MM... Failures can and do happen do to the nature of the hobby...

[Finnster]

I ran mine all the time w/ 5s A123, tho mine is older and runs w/ 5s lipo as well. Hell I used to runs 16 nimh cells on it before I got lipos and that was 23V+.

A123s usually drop to 3.5V/cell quickly off the charger, and the MM is rated for 12 cells nimh. NIMH charge to 1.45V/cell, so that's 17.5V either way

[SunnyHouTX]

I've been running fully charged 5S Lipo without a problem, on old and new versions of the MM ESC. Cooling fans are a must.

[snellemin]

Heck I run 6s1p A123 on mine without issues.

[Sammus]

Originally Posted by Arct1k

5s2pA123 is equivalent to 4s1p Lipo - This is a pretty standard setup with a modded MM... Failures can and do happen do to the nature of the hobby...

I'm not sure where you heard that... 4s lipo is 16.8V off the charger, 14.8V nominal. 5s A123 is 18-18.5V off the charger, 16.5V nominal. Just a little higher voltage. And I plan to run 1p not 2p.

And yeah I've heard of lots of people running 5s and even 6s lipo succesfully, but I've heard of many more failures at 5s lipo - even just connecting the battery and it goes up in smoke before it arms. I'm guessing those esc's were on the low end of the tolerance margin.

I'm wanting to hear from somone who's has failed on 4s lipo or 5s A123.

Fwiw I will be running a big cap (1800uf 35V FM series ultra low esr) a ccbec and maybe a TVS across the input. I will add a fan if it gets warm, but my sidewinder ran cooler the more voltage I threw at it, so I'm hoping it wont heat up too much more :)

[Finnster]

Originally Posted by Sammus

I'm not sure where you heard that... 4s lipo is 16.8V off the charger, 14.8V nominal. 5s A123 is 18-18.5V off the charger, 16.5V nominal. Just a little higher voltage. And I plan to run 1p not 2p.

And yeah I've heard of lots of people running 5s and even 6s lipo succesfully, but I've heard of many more failures at 5s lipo - even just connecting the battery and it goes up in smoke before it arms. I'm guessing those esc's were on the low end of the tolerance margin.

I'm wanting to hear from somone who's has failed on 4s lipo or 5s A123.

Fwiw I will be running a big cap (1800uf 35V FM series ultra low esr) a ccbec and maybe a TVS across the input. I will add a fan if it gets warm, but my sidewinder ran cooler the more voltage I threw at it, so I'm hoping it wont heat up too much more :)

Because its loaded voltage what counts. Here's two graphs of a 4S and a 5S A123. Try to tell which one is which: (i've already given a bunch of hints )

[Sammus]

Good point, they do look about the same, dropping about 1V at a constant 50A draw. My guess is graph #2 is A123. based on not a lot. they really do look very similar.

I guess my point though was that I'm worried about toasting my Mamba Max - and have read several times of people letting the smoke out simply plugging in a 5s pack which lead me to believe it was the initial voltage of the pack which was the issue.

Its no worries though I just powered up on 6s A123 that was fully charged last night (cell voltage was average 3.35vpc this morning) and it worked fine. My ammo 3300 didnt really like being held pinned unloaded though lol... seems to still work fine but made a funny noise. I didnt even think about the fact it wouldve been doing over 60k rpm before I tried it, a bit much from a $35 motor I think :P

Second thing is even unload just blipping the throttle on and off like that my max's heatsink got warm. on 3 or 4s it didnt change from ambient doing the same thing.

I'm surprised about the amp draw though, with my multimeter reading voltage (fairly slow refresh too) going full stick from a stopped motor made the pack drop from 19.5V down to 17V - much more than I wouldve expected for a bare motor shaft (not even a pinion!), and probably more than that anyway if I had something that refreshed more than two or three times per second.

Anyway.. my buggy is on the way, and if they dont work to my satisfaction I'll invest in some 4s 3700mah polyquest packs.

Now all I can do is cross my fingers and hope that spare parts for the lightning 2 buggy are still available once the D8 is released...

[Sammus]

I was just thinking, would 4s2p be a better option?

[Xtremespeed]

Ive been running 4s2p A123 for a long time. No issues with the MM. Been considering
5s2p but trying to wait on the MMM for that. Trying!

[sleebus.jones]

I was running 5S A123 through a mamba max with no problems. Ran my Emaxx that way for quite a while with a 10XL on it.

[RBMike]

I'm running 5S(1P) A123's in a buggy with the MM (modified) no problem. 2Kv Medusa & 15/46 gearing. On a 90 deg day, everything is about 130 to 140F after 6 to 7 minutes on the track.

[Pdelcast]

Yeah, all you guys having no issues. The Mamba Max was not designed to run on 5S. I don't care if it works fine, it wasn't designed to run on 5S. Stop it. Don't.

If you are running on 5S, don't tell me. I don't want to know about it.