Medusa 36-50-3300 Vs. Ammo 36-50-3300
 

I've been thinking about building a nice brushless Maxx for a few months but had been waiting for the Monster Maxx(like everyone else).

About three weeks ago I decided to just get a new 3905 to play with stock till the new ESC hit the streets. Thinking I would need 2000w to get the performance of my Big block T I didn't figure the MM would handle the power I desired.

After reading a few posts of others planed setups I decided to give the MM a try with some small high KV motors I had on hand.

I started out with a Hacker C40-8L on 4s A123 with a 15t pinion. The motor and ESC ran happily with this setup and it had great accelleration but just couldn't pull enough gear(19T) to reach the speeds I was looking for.

I had the Ammo in my converted NMT so I figured what the heck, turn the shaft down and use the 1/8" pinions I had and let the testing continue:party:

I started out with the Ammo on 4s and the 15t pinion and it was a dog, popped in the 19t and top speed was ok but it wasn't very quick out of the corners. Switched to a 5s2pA123 pack with a 13t pinion and the motor started coming to life, but was running a bit hot. Tried out a 15t pinion and speed and torque were awesome but the motor was getting HOT(no heatsink yet) went back to the 13t for a run and the motor siezed up the front bearing, and got very HOT. Replaced the bearings with some I had on hand I think they are ultra seals?? Ran it again temps still went real high and I was thinking I might have de-magged the rotor when it siezed up. So I started looking for an afforable quality motor as a replacement. Found a few threads about the Medusa V2. Being familiar with Medusa from helis I decided to try one out.

In the mean time I picked up a heat sink for the Ammo and seem to have the temps under control now, maybe. Needs some more testing yet.

Any way some pics of the test rig.
http://i287.photobucket.com/albums/l...6/DSC05049.jpg
http://i287.photobucket.com/albums/l...6/DSC05053.jpg
http://i287.photobucket.com/albums/l...6/DSC05055.jpg

I had porblems with my temp sensor on the first run with the Medusa on 13t today but temps never went above 100f. Felt less powerful than the Ammo with the same gears

http://i287.photobucket.com/albums/l...005s2pA123.jpg

Fixed the temp sensor for the 14t run. Temps rose to 114f after I powered down the ET(I have an MIP onboard on it right now also to keep an eye on the temps)Power was at or a bit better than the Ammo on 13t now.

http://i287.photobucket.com/albums/l...005s2pA123.jpg

I have a few logs from the Ammo before I put on the heat sink and installed the cooling duct so I want to retest that motor once I find the limits on the Medusa.

The next run will be with a 14t pinion and a 65t spur, followed by 15/68, and possibly 15/65 if it's not building up to much heat. Future testing will log the temps on both the ESC and Motor also but wont have RPM

In the end I'm almost happy with the power I'm getting on the 14/68 gears, wouldn't mind just a touch more top speed, so it seems I only needed half the power I thought I would to be happy.

As to what it takes to make me happy as a basher I like enough torque to pull wheelies at 10-15mph and enough top speed to jump the two lane gravel road in front of my house. These two goals were met with the 14t pinion, I still want just a touch more:yes:

Stay tuned to see how the $35 Ammo($50 with the new bearings:no:) stacks up against the $110 Medusa.

BTW, I seem to remember reading that 4 pole motors should have about 15deg timing on the ESC, I'm running the default 10deg on the MM and have noticed a few quirks running the Medusa at low speeds, couple times it sttutered a bit and once it seemed to hit reverse then buzzed, I let off the trigger almost instantly and it drove away fine so I'm not sure what happened??

You may want to turn the start power up with the medusa, and disable the punch control. I usually leave the timing to normal, as higher timing seems to cause extra heat. It does make more power with higher timing, but I am not usually looking for more power! Just trying to smooth out the power from a standstill,

Graphs look good, thanks for the info. I have a 1500kv 60mm medusa coming, and plan to run it in my hyper8 buggy on 6s lipo.

Cool, Thanks for the tips. I also dont think I'll need any extra power from the timing advance.

I did a little rearranging and harvested a small fan from a laptop for the ESC, it was getting up to ~140 yesterday with ambiant temps in the low 60's, so I turned it 90deg heatsink forward from the pics in the first post(hard to see with all the wires) and if that isn't enough I'll hook up the fan. I'd like to see it about 60deg above ambiant. Got bored waiting for the sun to come up this morning, LOL.

Ok graphs with the 14/65 gears, I split up the data so the graphs aren't so messy.

http://i287.photobucket.com/albums/l...avoltsamps.jpg

Temp1 is the motor temp2 the ESC.
http://i287.photobucket.com/albums/l...temp1temp2.jpg
http://i287.photobucket.com/albums/l...sawattsmAH.jpg

I could probably push it harder yet, but ambiant was 43f when I made this run so I think this is the limit. Speed was decent up a little from the 68t spur, darn near cleared the down slope on the far side of the road, wheelies up to maybe 10-12mph. Stuttered on one start up. I'll turn up the start power and see if it helps. Then back to the Ammo for the heads up portion of this thread.

How do you like these titanium beadlocks?

Ok turning up the start power seems to have helped, Thanks much Linc!! Drove off the last half of the pack.

http://i287.photobucket.com/albums/l...sthalfpack.jpg

Next graphs will be with the Ammo on the same gears.

Serum, I just got them about a week ago but so far I like them enough to want another set for the T.

Ok here is a graph with the Ammo on the same 14/65 gear set, only other change was I went back to low start power on the ESC.

http://i287.photobucket.com/albums/l.../14-65Ammo.jpg

Even though the motor is running well outside its comfort zone it was putting down big power, at least 5mph faster than the Medusa, more torque, it's like it's a much higher KV motor. I'm going to gear down till it feels close to the same speed as the Medusa and see how the temps are.

You got them from DUH engineering?

Wow I'm down to an 11t pinion the Ammo is still as fast as the Medusa on 14/65 maybe even a touch faster, torque is better, lifts the front end much easier at higher speeds, but the temps dont want to drop. Maybe a drop in timing advance would help at this point??

http://i287.photobucket.com/albums/l.../Ammo11-68.jpg

Serum, Yes, They are from Duh

Pic of the distance I've been launching it today.

http://i287.photobucket.com/albums/l...w46/Bigair.jpg

The red line is the first point of contact

Interesting. So essentially, the Medusa is a far more efficient motor, while the ammo is just freakishly powerful but runs like a heat pump.

Hey Buzz, I compared the 56/1800 ammo to a feigao 15l (1600kv or so). They had similar performance, even though I had to use a larger pinion with the feigao to get the same top speed. I could not get the temps on the ammo to go down. I tried really low gearing, and even geared it up. Higher gearing just made it hotter. The feigao could pull higher gearing and did not get as hot. I got rid of the ammo and stuck with the feigao.

You may be able to gear the medusa up more, and see how it does. Being 4 pole it should have more torque.

I plan to test the medusa 60/1500 and an align 600l, hacker b50 15l, and the feigao 15l in a 1/8 buggy on 6s lipo. All are similar kv, and I will gear for the same top speed and use my eagletree to get some data.

Great tests BTW, very interesting info!

I concur that you should try gearing up the medusa motor as 4 pole motors like to have quite tall gearing.

I'm almost wondering if I didn't de-mag the rotor when that bearing seized. I know it wasn't this fast on the 13/68 gears the first few times I ran it. Oh well, at least it was cheap.

I dropped the timing advance to 5deg just to see what effect that has, if it dosen't help I'm just going to bin the Ammo.

Well dropping the timing did help with temps slightly the Ammo is still running way hot! 2.5 min of running and the temp peaked higher than the Medusa after 8 min of bashing around in warmer weather.

Done with the Ammo in this App. I have a small boat I might try it in with water cooling??

I'll try some steeper gears with the Medusa also, looking at the graphs I see very few points over 75 amps. I also want to try increasing the timing slightly with the Medusa, I found in the literature that came with my motor an 8-15 degree timing reccomendation.

I kind of like the punch the Ammo has, the Medusa seems to be smoother, easier to control the power. The punchyness keeps you on your toes becuase you never know for sure if it's gonna slip out from under itself, so somewhere in between the two would probably be my ideal.

I just spent the last few hours putting the Medusa back in and doing some quick runs in the yard just to see what kind of peaks I could pull on taller gear ratios. Started with a 15/68, pulled about 80amps. Went to a 15/62 and pulled 91a. I figured what the hey and tried 19/68 and pulled 106a and it still dosent have that kick the Ammo does.

I honestly dont need any more than I was getting with the 14/65 gears so I put it back to 15/68 and I want to run straight through a full pack, right down to the LVC to chrck for temp issues. If I can make it through a full pack with out temp issues I'll start tweaking the timing. Cold, windy, and snowing this morning:(

Water cooling will make a huge differenc in temps. I tried a sv27 6 pole motor in a few different vehicles, and it ran too hot with just air cooling. With water cooling, pushing the sv27 at 42mph it does not even get warm. Something about having a billion gallon radiator seems to drop temps!?