Ok thanks, i saw that but thought you needed a rotating assembly for the sensors, like the Revo Optidrive system. But if it runs on magnetic feedback, wouldn't it be similar to a sensorless except sensorless doesn't use a circut board to detect movement?

Both, BEC and ESC power, one is less important but second is prone to overheat the PCB.

It is possible :) but is it easy or not I am not sure, sorry for not clear answer.

Artur

Sensoreless based on feedback from phases, which only exists when motor spins, while sensored feedback doesn't require rotation to point out rotors location.

Artur

....And the slower the motor spins, the smaller the 'back emf', so the less easy it is for the controller to detect the rotors position - hence cogging at low speeds.

If I read correctly some where. Can't you bypass the first 6 cell group and run a ubec to power it. The run the 16 cells like in a series on the other wires. The main hot and ground wire.

No.

There is no way to substitute built-in power for logic and brains with external power without modifications on PCB.

Artur

Ok, it is working now. Almost plug and play :)
Requires some tweaking on sensor side, I will share info with Feigao, hopefully it can be resolved.

So far works as expected. Too bad its raining outside.

Artur

Well is other companies going to make a sensored esc. I would hope so. I would like to see a 8s lipo capable esc with sensored smooth running.

I have got a bunch of new stuff coming for my maxx. 977 charger, 9L and a HV-Maxx setup. I will try out the HV-Maxx and then I think I am going to try the 9L on it as well. Could be a month though, but I enjoyed this writeup Arthur.

12 Cells, 6XL, 66t Spur, 21t pinion
 

Next would be mods on ESC.

By the way do not use reverse with Novak HV-Maxx or use it carefully, because going from forward to reverse is safe but going from reverse to forward... you can snap everything in your truck with big motors :)

Artur

P.S. Thank you

I hope so...

Thanks for the replies, I look foreward to your research. Can you rewind a hv to a higher wind? I have a wierd idea that if i could get somebody to rewind it, it would be more dependable and run better

I do not see why not, but you won't get more power from it. But can help in selecting gears.

Artur

I was thinking about lowering the kv of the motor. I'm new to brushless, though i've been reading about them for years. I've heard all the arguments about the HV reliability issues and have come to one conclusion, the kv is too high and stresses the esc when it maxxes out, the timing change doesn't help either. So i want to try a few turns higher and move the torque curve a little lower where it might be more useable and increase reliability.

Does anybody know how manny turns a 4400 is?

Ok, I run it for 8-10 minutes and then ESC thermal :)
6XL is a serious motor (doesn't even need heatsink), but it was grass and second gear. Torque was great, maximum speed can be better. Overall I think e-maxx would be a rocket with sensored 9-10L. I will try to measure current draw later.

Artur

P.S. Batteries were almost drained as well, 300mah left from 4100+mah.
Need to work on better cooling...

cool i figured the 6XL would be too much, think a 9 or 10 XL would be a better setup

A 10L would be great, a friend of mine had one on his savage and was able to hit the 45 mph on 15 cells.

Mods to make ESC run Cooler...
Remove silkscreen from power lines on PCB and upgrade with solid copper wire.
3 Runs heat is not an issue but differentials are gone. Front differential - main gear broke, rear diff. satellites gear broke (Milling the rest of aluminum housing :) ). Looking forward for 1/8 diffs bulkheads conversion...

Artur

Why didn't Novak do that?

good question there is a lot of things novak could do to get their products better but the dont.

Cost would be always the main, then specs and goals. On paper ESC rated at 375W, which is safe with current setup, but there is room for improvement and it is always nice to offer warranty when you have good setup.

When I attached 1200W motor and increase load a little bit, now with given internal resistance of only 2 FET's per phase, heat transfer and dissipation should be addressed. While current capabilities are sufficient, internal resistance is somewhat high, and in stock configuration (taking into consideration de-rating factors) is good for 30-35A continuous without overheating, which is about ~450W @ 12 cells. Adding extra copper increases thermal mass and improves conductivity on PCB, but adds weight.

So in stock configuration if you keep current under 30-35A (Average current) then you should be fine. This can be accomplished by installing high turn motor and achieving the same powers with voltage rather then current.

Meanwhile I will be exploring possibilities of high cell count in stock form and possible mods.

Artur

Are you going to offer that service for a price? I'd like to have it done but not sure i could do it.

Which motor you would like to use and how many cells?

Artur

I was thinking about a 7XL and no more than 16 cells or 5s lipo, anything more would be ridiculas. Before i do this i want to see if the HV is any competition for the nitro's around here as a new track is opening soon, If i get blitzed i will be talking to you.

That's a pretty good idea by adding solder and wire to the traces - gives the trace a bit more "meat".

To increase the current capability of the ESC in general, what about simply adding a couple more FETs per phase? Those TO-220 style FET cases make it pretty easy compared to the surface-mount IC types. You'd probably have to add a PCB extension then use a different case - it would add a bit more weight but worth it IMO. From the pic, it looks like the source and drain leads are directly paralleled on each phase. From there, you'd have to see if the gates are directly paralleled, or if there is a resistor. The end result probably wouldn't be pretty, but you'd have roughly double the current capability and would heat up less due to the lower total "on" resistance. Just an idea...

Ok.

Just keep in mind, hv with feigao motor has different performance then stock HV-Maxx combo. It would be fair to say compare 7XL performance on 16 cells with tremendous amounts of torque vs. Nitro's.

Amount of starting torque, based on motor type of simular size (power):
Brushed - up to 1000%
Brushless sensored - 250-300% (up to 500%)
Brushless sensoreless - 20-35% (less then 50%)

Artur

Yes, thats the way, but not much you can do under Novak's "hood", but if you redesign power FET's PCB and re-use HV daughter (brains) board, then extra performance can be achieved. It can be packaged different as well.

We will see on demand :)

Artur

Hey Crazy, on that many cells or on 5s lipo, for racing, you might want to consider like a 9xl. My 10xl on 14 cells is already to much for a track. I can't wait to go to 6S lipo but im sure I'll have to turn down my epa alot.

I was refering to max cells, probably run 12 cells or 4s lipo for racing

Well, I finally converted my HV-Maxx setup to a sensored 9L.

I had a very hard time matching the timing of the motors just based upon hooking up the motors. It probably has to do with the can size, though Artur didn't mention it with the C50 motor. I probably spent 2-3 hours testing amp draw. I got it matched pretty well I think.

It was very dark when I ran some GP3700 6 cell packs though it. I was running my HV at 12 66 gearing. I am going for cheap here, so I drilled out a set of pinions for the 9L (it is a C can with a 5 shaft) . I ran 18 70 for the 9L. Wasn't extremely impressed by the top speed as compared to the HV, though it was dark. Controller was warm after a couple of minutes. Tried some GP3300 7 cell packs and it really picked up in speed. After a few runs with it, controller wasn't too warm, but motor had picked up some heat.

The brakes are too touchy now. At this moment, I am using the traxxas radio, and coming off full throttle to brakes anything over 1/8 trigger = flipping it on the lid. Artur, how were the brakes on your setup? I have a MX-3, need to get crystals for it though, but I will have to change the EPA if I want to drive this thing. I was being so conscious of not trying to flip it over, I clipped a sidewalk and broke all mounting screws on the plastic skid plate and bent the ears of my T-Maxx frame down. :019:

The HV-Maxx motor is pretty heavy, if I decide I like the setup, I will take the heat sink off to try and save some weight.

Very good news, I am hoping rock-crawlers will jump on this setup.

Yes , brakes are very strong. I set mine to 45% only.
You can easily remove heatsink (by the way good heatsink) from HV-motor and use it somewhere else.
Sorry for C50 hassle, I thought that i published picture on its wiring. It is quite different from feigao.

Artur

No, the C50 motor did not throw me wiring wise. I thought that the smaller can motors would be harder to match timing to the HV motor by just hooking them together, and I wondered if the C50 gave you that problem.

I have also made this idea work for a lehner basic 4200 and a novak 10.5 running on the old SS5800 controller. I haven't road tested it yet, but it works well on the bench. I did cheat and use an o-scope to get the gearing lined up.:whistle:

I just thought of something, we can use the slave motor to do the braking using a standard brushed ESC and some diodes!!

Why not using it to charge battery pack?

I don't think charging the batteries (Lipo) is a good idea... I think the only batteries that can handle the currents would be A123's... but then again, it would be for a short period, so who knows, maybe it could work?

Arthur, are you still running this?

whats new with the feigo motors?

Probably could work, hadn't thought of it. Regenerative braking is usually such a small affect that it is proably more work than it is worth.