Brake fade?

[bdebde]

I was doin a little parking lot bashing with my buggy today, with a new set of road rages on it. After running a while, the brakes seemed to "fade". I cranked up the brakes on the radio from 75% to 100% but that only helped a bit. Normally, at 100% the wheels lock up, even sometimes at 75% if it's a bit dusty. I have the brakes set to 75% (*edit: it is only set at 50%*) in the mamba settings. I think it may be running a bit hotter now as well, not sure as I was about done with that pack. I did try it again later after charging the battery again, but still kinda soft brakes. I am going to doublecheck the settings again and see if any difference there.

So, do you think I lost a fet or 2. I suppose the brake fets are not connected to the heatsink (anybody know?)? I am just getting this rig dialed in and hate to send the Mamba off for repair now. Guess I better get a spare Mamba just to have around (have em in 3 rigs).

[bdebde]

Any Ideas anybody? Do you think this may be cap related instead of fet related? Guess I could put some caps on it to see.

[nativepaul]

I have a buggy with 8XL, MM, 12 nicads and road rages,

I have noticed no brake fade but I get only 10 min runs so maybe I'm not running long enough to fade.

I'm not running a track, just road bashing so its possible that i'm getting some Very minor fade but not noticeing, it will still lock em up all through a run tho.

What buggy is it? I set my MM brakes to 30% on the MM it will lock the lightest tyre, 40% locked all 4 road rages on my lightning 2 pro at 8lb 12oz.

Whats the temp on the MM? When I changed from the factory MM brake settings to 30% I stoped locking all the tyres, my braking distances got much shorter and my MM got about 10-15deg C hotter, maybe if your allready hovering just under the overtemp cutoff point at the end of a run it wont brake hard and push itself over the edge into thermal shutdown.

[bdebde]

I also let it cool off and tried it again later, but the brakes did not come back to normal. Had Mamba set at 50% with radio at 75% (37.5% total) and it would lock em up with most tires. I tried setting the brakes up to 75% now on the Mamba, and it stops good, but still won't lock em up. I haven't got the temp probe out to check actual temps, but it was normally only warm to the touch, now it is hot to the touch (no thermals that I could tell). Buggy is Sportwerks Mayhem.

*edit: also noticed some cogging at low start speeds now, used to be real smooth.*

[snellemin]

I had a similar problem with 2 MM ESC's. It was smooth, braked hard and I was bragging left and right. Then slowly the brakes faded and I got less power. Cogging would get worse and then one day ....BOOOM!!...ESC smoked. I'm still waiting for my replacement ESC from CC. Brake was always set 50% and drag brake was at 10%. My last ESC blew all 3 caps. And I'm running a fan on my ESC too, making me wonder about the qaulity. My buddy has his ESC since last year and still going with the exact same setup that I have.

[nativepaul]

Hmm I didn't think of the drag brake, but that could have a very big effect, I spend a lot more time rolling round corners off the throttle than I do with the brakes on.

If it is still faded after a rest then it is not temps like I originaly thought.

My MM has always had occasional but pretty severe cogging at low speed, I hardwired my motor, but my batterys are old and crap so I think they just can't supply the juice needed.

I hope you get to the bottom of it in the end, keep us posted.

[bdebde]

Update here- The trusty Mamba Max is FINE! Turns out my 8XL burned up and it is only a week old. I put my 7XL back in it and all is working fine. I still had the brakes cranked up and nearly flipped. I guess it may be time to get a more efficient motor.

[BrianG]

Until CC gets the software update for the MM to run Neus, that leaves the Lehner motors. Unless you can deal with the cogging...

[bdebde]

I hate cogging! I wonder if a Plettenberg bigmaxx would work with the mamba? Can't seem to find lehners anywhere, and I have been looking for a while.