Hey everyone, new here, but lookin forward to chat with everyone now that I've made an account. I've got a rustler that I put an ezrun 8.5t/60a esc combo in and also bought a new charger(thunder ac6) and new battery(sky 5000mah 40c). Anyways, I charged up the battery and left the esc at 3.4v cutoff and took it out for a run on the streets and it cutoff only about 5 min in and the esc was flashing red. So I set the cutoff to 3.2v and tried to run again but only worked for a few min then would slow down to about 50% power and cut off periodically. I checked the voltage of the battery on my charger and it was at 3.93 v per cell. Is this a manufacturer defect or is this typical and I should drop it down to 3.0 or 2.8v cutoff?

From what I have read, the Hobby Wing cut off is terribly inaccurate. Keep lowering the cutoff until you measure the battery voltage at 3.5 volts or whatever you want it to be.

Don't go too far, remember the voltage will recover, bounce back up after stopping. The low voltage cutoff happens with the voltage pulled down while loaded. Best to have the resting voltage at least 3.7V per cell or so. Stop as soon as the power begins to drop off.

Ok thanks for the advice, so I want it at about 3.7v when not under load, ie: it being plugged into charger to see the voltage left in the battery? Will I really get that much more runtime from 3.9-3.7v? 3.9 being where it was at when I last plugged it in to the charger

Yes, and it does appear you have quite a bit battery left, 3.9V per cell is likely a little over 50% charged.

A typical resting voltage vs capacity table, based on discharging at 1C to 3V. Of course this will vary some by cell but most such tests/tables I have seen over the years are fairly close.

4.20v = 100%
4.03v = 76%
3.86v = 52%
3.83v = 42%
3.79v = 30%
3.70v = 11%
3.6?v = 0%

Most recommend limiting discharge to about 80% (20% left) for better lipo life.

Couple things here...lipo's dont really "drop off " in power, not like nihms. They will cut out, plain and simple. If you're dropping 50% in power, then you have other issues.

Check your ESC settings again, obviously make sure you're in lipo mode and as for cut-off, really 3.4V is ok as you dont want your lipo to touch on the side of 3.0V which is the bare minimum. Some like more volts to protect the lipo which I can understand, I run 3.5V which is pretty safe IMO.

Check your ESC, motor and lipo temps to see if you're running too hot....if anything touch the side of the motor at least and see if you can hold your finger onto it for at least 3 sec.
To me it sounds like its a heat issue.

Some ESCs will reduce power for a bit before cutting out when LVC kicks in, to allow getting out of the way of traffic, off to the side of the track.

I felt everything and nothing was hot, yet alone barely warm, I'm at work atm but I'm goona put the lvc down to 3v and drive till it cuts off and see what the charger says the voltage is, sounds like I should keep doing this until it sits at bout 3.7v on the charger?

Looks like 3.4V is max for lipo threshold and I guess this ESC reduces power by 50% for a couple seconds when hitting LVC...but then it supposed to shut down I believe? I dont think its supposed to work periodically? I didnt see it but is the ESC supposed to flash red when LVC is hit? Or is trhat something else?

But I would NOT reduce it to 3.0V LVC....just for safety sake. You shouldn't have to and really, you should get decent runtime with a 5000Mah 2S lipo without resorting to lowering your LVC.
Are you sure you're charging your lipo fully to 4.2V per cell? And your ESC is not getting hot? Because thats one of the safety precautions they built into that speed control as well.

I dunno, I would re-calibrate the ESC to your transmitter, check all your settings for the ESC, charge your lipo up FULLY and try again. And of course make sure your Rustler is GTG (pinion/spur mesh, wheel bearings, etc.)

Battery was fully charged each try, esc was not even warm when I felt it, think its faulty or is this normal for an esc to be off by so much? I'm going to run it in about half hour when I'm home so ill set it to 3.4v again and see how long its lasts, thanks for the help so far, will post back in an hour or so with updated info

So just ran it, battery at full charge, lvc at 3.2 I think,forgot to check, ran for about 15 min, plugged I to charger and both cells read around 3.96v.... Should I contact hobbywing or just put lvc down to 3v? Thanks everyone for the help! Much appreciated!!

So it cut out after 15 min? And nothing else is hot to the touch?

Email HW (or wherever you bought it from) and give them the lowdown on whats happening. Maybe theres a firmware update or the ESC is just faulty. Let us know.