Throttle loss... Help!

[dextan22]

My ascender is running an MMP, Roc412 1200kv, Castle BEC (servo direct), a Savox servo and a turnigy 2200mah 3s 20-30c battery.

Since its first run, when i crawl at really slow speeds uphill or downhill, i experience throttle loss which makes my rig freewheel down which shouldn't happen. At first i thought it was the 2-speed gear disengaging, the servo maybe or my TX setting, i thought it was disengaging and going to neutral at very low speeds. Hence the lack of throttle and drag brake. It happens only during very slow crawls uphills or going downhills.

This afternoon i found out that it wasn't the 2speed gears or shift servo at all but probably the motor or the esc, or something else. It happened almost all the time while i was crawling up or down and it was annoying. I pull the throttle trigger to slow crawl and then after a few seconds i experience throttle loss, and while not letting go of the trigger, still keeping it pressed (fully depressed or moving it trought the trigger motion but not full release), nothing is happening, no noise from the motor or gearbox, non from the esc too. No drag brake. It's like the motor has no power at all.

But once i fully release the trigger and press it again, i get throttle power once again.

I also tried running the rig at full speeds for a long while just to check if it happens not just during slow speeds but i never experienced it once when i was running at full speed. Stopped did a slow crawl uphill and without fail my rig freewheeled down again. I also tried slow crawling on flat ground, no throttle loss. The motor, esc and battery aren't even warm.

I am guessing it's the motor as it's a used one i bough off the rcc classifieds. My mmp, battery and bec and servo are all new. But i really don't know. Could the battery be too weak at 20c-30c? Maybe a higher discharge rate?

My MMP settings are sensored mode with 0 timing.

Anybody have any experiences like this? Any help would be apprecated.

[robertjpjr]

If you haven't, reprogram the ESC / rebind the TX. Check your sensor wire, it could be loose and not delivering the low end that you would expect. The battery will function but that is a low amperage battery. 2.2x20 = 44 amps. Meaning your motor "could" be starved for amperage. I've run those exact batterys and I pushed them too hard and they puffed on me. Could just be my bad luck though.

[dna4engr]

For some reason you are losing your sensored function. You stated you're running in sensored mode on the mmp. Did you select smart sense or sensored only. Make sure you've selected sensored only.

Have you double checked the sensor cable connection between the esc and the motor is plugged in correctly? These can commonly be loose even if they look well attached. Also check the pins for the sensor cable, are any if them bent or missing.

Let us know.

[dextan22]

okay i'm back. thanks for the reply guys. so here's what i've done so far:

- tried another Rx. nope.
- tried 2 other sensor wires and made sure they sit nicely on the plugs. nope.
- tried a 4000mah 60-120c 3s battery. nope.
- made sure the setting is at Sensored only. nope.
- tried Smartsensor mode. nope.
- tried switching with an extra MMP esc and made sure all the settings are similar. nope.
- disconnected everything but the ESC from the Rx. throttle still dies.

one thing i should note is that the MMP's led is giving me a blinking forward flashing light, even if i press the trigger fully (once it shuts down), this happened in both MMPs i tried.

also, the only thing i haven't tried to replace is the motor since my extra sensored motor is a pro4hd and it won't fit the ascender.

and as usual, this only happens on slow speed uphills. very frequent now.

i ordered a cheapo sensored 540 motor from hobbyking to rule the Roc412 out. i will also try to clean it while waiting for the other motor.

dang! and the ride on this rig was so good.

[jouni]

maybe sensor board of your motor?

[dextan22]

yeah i guess so too. i forgot to mention i also ran it sensorless and didn't experience any shutdowns.

is the Roc412's sensor board user replaceable?

[yotapower07]

Curious to know if you have the esc setup on forward/brake/reverse or crawler reverse?

[dna4engr]

Originally Posted by dextan22

yeah i guess so too. i forgot to mention i also ran it sensorless and didn't experience any shutdowns.

is the Roc412's sensor board user replaceable?

Yes the sensorboard is replaceable. One of the nicer features of the roc412 and pro4 motors. The redlines were replaceable but you had to unsolder the motor terminals.

Before replacing it try cleaning the sensor. Take some electronic cleaner (lhs should have it, basically brake cleaner) and spray her down good and allow it to dry well before reinstalling. I never thought to ask how much dirt or dust you've driven in. A buddy of mine had this issue before with a motor and after I cleaned the sensor for him it worked perfectly until a while later when it finally gave out.

Dna

[fish-hunter]

What radio are you using. I had a spectrum that did the same thing.