5 cell + mamba 25 in a tenth scale for racing?

[Serum]

Still not a setup i will advice you, but i am not stopping you...

on 5S the 2400 rpm/v motor will fry that esc at the first run..

[danverz]

Hi,
I agree with Serum. I won't use a mamba 25 on a 1/10 car.
In my past experience I saw 100A on a 1/10 car with a 2S lipo.
I also like to say the Quark 33 is able to be pushed to 50 and has surely more
current capabilities than the mamba one.
Yes I know you want to use an HV setup, and this will keep Amperes lower,
anyway I do not think this is a good choice.

Ciao,
Daniele

[jhautz]

Here are pictures of that xxx4-G+ with the Quark33 and the neu. I found in an old email that it was an Neu 1105. Thats a really small motor. He ran a 2100mah Lipo pack. Basically a 1/18th setup, but the xxx4-G+ is so light because its all graphite that it weighs the same as a Losi Mini LST which runs fine on a heavy duty 1/18th setup. He claimes his buggy was running 1lb lighter than his buddies xxx4 with a Novak GTB 4.5 and 6cell and had better acceleration. Also claimed a 30 minute run time, which I have a hard time believing on only 2100mah pack.





Don't forget I think this worked for him cuz the 1/10 he was running was so light. If you try this in a rustler or something you will likely not have the same sucess. Also notice the BIG fan over the esc in the pictures. :eek:


Why not try the Quark 33A instead of the mamba25. The Quark is at least rated for 5s Lipo and has a heatsink which I think will at least give it a chance.
http://www.quarkbrushless.com/pro_procarcontrol_33a.htm

might want to give this a quick read through...

http://forums.radiocontrolzone.com/s...+stadium+truck

Bye:018:

thanks guys for digging up the pics, and link; very inspiring!

Doing some testing of my own also. Mamba 25 does run on 5s:027: ! Current test rig is an emaxx with a 980KV Himaxx 2808 1.83 oz. 8amp. cont 12amp burst. gearing 66/12 takes of well in 2cnd gear. gearing 66/16 2cnd gear cogs terrible from dead stop, but If I take of in first just to get rolling second will pull strong from a crawl even on a hill. Testing was a gradual 6 nimh lowest gearing, 3s, 12 gp 3300, gp's + taller gearing, 5s in first, and finaly 5s in second. 5s with 66/16 cogs some even in 1st when the battery is fresh of charge:002: . With 66/12 is very smooth, but packs were not fresh, need to top of packs and test again. Top speed with 66/16 should have been around 10 mph. Motor always stays cool, speedo does good even in grass. the only times the speedo heats up are, cogging, pulling up against side of house and lighting up tires on brushed concrete (full throttle 1st gear temp gun aimed at speedo the whole time took a few seconds to come to 180, then overshot just over 200f still ok) , and climbing the hill at very low throttle inputs (full throttle repeated passes are fine even in second+tall gearing), but two crawling speed passes up the hill in second heat it up 180+. All of this testing was done with the factory shrink wrap still covering the speedo, temps recover very quickly from these situations while driving normal. I plan to put a heat sink on it if it goes beyond the testing phase. 5s definently seems hotter than 4, but air has warmed up alot to. Also I believe higher voltage brings in more amps, and when geared so as that 5s top speed matches 4s top speed amps should be close to equal will have to test more latter. 5s with lower gearing feels very smooth. tuck weighs 7lb. 7oz. with old 10c 5s 1800 + reciever pack. I think it could push 20 mph in a light 10th scale if I had enough gear. This is not the motor I intend on running; it's the only motor I have that will take 5s, just trying to get a feel.

sorry all. the 2808 was my old motor upgraded last summer to a 2812 850 kv 2.3 oz. 160 watt 28 x 29mm. 4-11amp 14amp max 15 sec. 1.6 in.oz./amp. This throws the #s of some. speed was calculated mathmaticaly @ 12mph for the 980 taking into acount a fair amount of sag for the older pack, so 10 still isn't far of. With a fresh pack 66/16 gear I can't run fast enough to keep up while holding the remote, if my hands were free I could.

***Also found another possible motor looking for opinions e-flight six-series 28x36mm 2.9 oz. 2000kv 6-pole 26amp 32amp burst 15 seconds. only listed for 3s, but 2700kv version is listed for 3s also. the 2000 on 4s would be less rpm than 2700 3s.

considering going 4s anyway 5s works, temps ok so far, but when something goes wrong (bad cog, part throttle abuse whatever it heats fast). Also I read the thread about finsters wife with the M.M. 5s failure. Also looking at flight power batts. 2170 is the smallest pack I found with 25-50c rating 4s is almost 8oz. 5s would be to much weight. According to the graphs this cell averages almost .2 volts per cell higher than there 20-30c packs. 3.5x4=14 3.3x5=16.5 only giving up 2/3's of a cell worth of voltage, and no longer pushing luck voltage wise. Thanks to Jhautz and Cemetery gates for showing me it can be acomplished on only 2 or 3s. 4s should be enough to make it exciting on our tracks.

Please give thoughts on the Six-series motor. I know the 6pole is like running a 2 pole with 3 times the kv from the speedos stand-point, but right now I'm running an out-runner (not sure how many poles, but alot, on 5s) also have seen more than one c.m.8000kv on 3s so the mm25 can keep up.

mamba 25 done. Did a 5s test with lower gearing, and freshly charged batts. Cogging not much of an issue with lower gearing, couple other quick checks ok, and staight to the hill for part throttle testing. I had already performed same test repeatedly with half charged 5s and much taller gearing. This time I expected temps to drop (lower gearing), I didn't even start up the hill and puff. It seems the fresh pack put voltage a little to high.

After this I got to talk to a very knowledgeable brushless airplane guy. Here are a few thoughts he had-
#1 - at full throttle fets don't work nearly as hard as at part throttle (what I saw in testing proved this even @ lower voltages, but went critical on higher)
#2 - out-runners are not the best motors to try to over power; they suffer iron saturation and act almost like a dead short when overloaded
#3 - cheap batts cause ripple currents ( a little spike getting through the cap would easily kill the fets., but the higher nominal voltage good batts would provide would not be good either on 5s)

So. if I want to continue I need to go with a top notch motor (Neu or mega), best quality 4s pack, and gear to use full throttle as much as possible