ESC possibly holding back performance?

[spaz163]

Alright heres the deal, I am wondering if my ESC is possibly holding back my buggy from its top performance?

I ask because my buddy finished his buggy build and we compared his and mine. His seems faster and much more punchy. He is running a Feigao 9xl, Quark 125B and Zippy-H 4s 5000mah. Gearing is the same on both buggies

My setup is as follows:

Ofna MBX buggy
Mtroniks Genesis Truck ESC
4s Zippy-R 4800 mah
Medusa Research 36-60-2000
Deans connectors on the batt and direct soldered on the motor

I am thinking that I may be able to get a MMM after X-Mas is over, would it be worth it?

Any input is appreciated!!!

[What's_nitro?]

Well, his LiPos are higher capacity. That means higher peak current draw- more punch. Also, the Feigaos are 2 pole motors, the Medusas are 6(?). 2 pole motors, in my experience, feel "punchier", or seem to spool up faster. I don't know much about the Mtroniks stuff, but the Quarks ESCs are very smooth. It may be the firmware in the two controllers which is making them feel so different. You could try swapping ESCs and see if that does anything.

The Quarks just flat out let the juice flow.I had been running a Quark 80b in my E-revo with a Medusa 36-60-2000.When I swapped out to a MM it lost almost 4mph off the top end,put the quark back in.Then I swapped out for the MMM it's about 1.5 mph slower,but so much better it's worth it.So yes the Esc can make a substantial difference in performance,and I believe the Genesis is a little weak,from the start.

[BrianG]

FWIW, Medusas are 4 pole motors. Not to mention Medusas are slotted stator, while Feigaos are slotless. Patrick explained the difference between the two in another thread (stickied somewhere).

Anyway, I think the difference in lipos may be somewhat a factor. The extra 200mAh X the C rating might be giving a little more current with less voltage drop, but I wouldn't think it would be that much of a difference.

I would place the Medusa 60mm a hair less output than an XL torque-wise. So maybe the smaller motor doesn't quite have the same grunt that the Feigao does for what you are looking for. Of course, the Feigao won't be as efficient, but that would be evident in temperature and runtime, which you didn't specify.

I would look at ESC settings (punch control or equivalent setting) on both. Then there's gearing. If yours is geared higher then acceleration will be reduced.

If you are just comparing ESCs, then the Quark is pretty close to the spec of a MM. I have no idea what the specs of the Mtronics ESC is, or the FET resistance, but that could play a small role.

[spaz163]

My Mtroniks Truck ESC is only rated for 80A continuous, whereas the Quark is 125A continuous.

I guess I am mainly focusing on whether the ESC can hinder the flow of current from the batts to the motor. Since the ESC is only rated for 80A wouldn't the MMM or the Quark allow more current to pass thus the buggy would be quicker all around?

Quite frankly, I am surprised that the Truck ESC hasn't turned into a ball of fire beings what I have put it through. It has treated me extremely well but I am just wondering if it would be worth the investment to go with a bigger, better ESC.

I am thinking that once either of the motors are spooled up, either battery pack can supply enough current.

[spaz163]

Originally Posted by asheck

The Quarks just flat out let the juice flow.I had been running a Quark 80b in my E-revo with a Medusa 36-60-2000.When I swapped out to a MM it lost almost 4mph off the top end,put the quark back in.Then I swapped out for the MMM it's about 1.5 mph slower,but so much better it's worth it.So yes the Esc can make a substantial difference in performance,and I believe the Genesis is a little weak,from the start.

Cool, thanks for the information, this is exactly what I was looking to find out. It is interesting that when you went from a controller that handles 80A cont. to a controller that handles 100A cont.... the speed dropped off. Not what I expected.

And yeah, my Mtroniks ESC is only rated for 80A continuous.

[BrianG]

An ESC with a lower current rating generally has fewer FETs, and that usually means the total resistance is higher as well. For a given current, the will be more voltage drop on the lower-current ESC because of this slightly increased resistance. Since motor rpm is a function of voltage and kv, that slightly lower voltage could translate into a loss of speed.

You gotta also remember that manufacturers rate their products differently. Some will rate the ESC based on the datasheet of the FETs without taking temperature derating into consideration, or allowing more headroom for the high surge currents found in car applications (compared to airplanes). From what I've seen of Castle products, they tend to rate their ESCs more realistically given the temperature and extra current headroom. For instance, the MM is rated for ~100A. The Quark 125B is rated for 125A. But the 125B and the MM use the same FETs and the same number of them. This illustrates my point exactly. Not knocking Quark, I love them, but you see what I mean.

Personally, the only advantage Quark has over Castle products is the smoothness of operation and the ability to run anything. However, with the newer firmware revision 1.20, Castle's ESC operate MUCH smoother and much more like how a Quark does.

[himalaya]

Right. The Novak GTB is rated as a 540A controller according to its instruction, such tough specs sound like it's going to be used in power plants, but in real world it's only a 90A ESC based one the FETs it uses.

[spaz163]

Alright, thanks for the replies guys. I think I will try to save my pennies and pick up a V3 MMM after X-Mas. It sounds like they have the bugs worked out now. Sweet!!!