Quark 80B Problem - Help please!

Hi Guys,

I really LOVE my Quark 80B, but it's acting strange if I drive with nimh packs. I'll try to explain it: If I'm driving sometimes the car just stops, and I can only steer, but no gas. After 5 secs or something I have to give full throttle forwards and after that full throttle backwards, then there comes some kind of strange beeping. (It's the same beeping as if you switch the on/off thingy to on, and then to "start the quark" you've to do the same as I said here above, and then I should drive normal with my car) And then I can just drive. But then after some driving the same happends.

First I thought it was the on/off switch who had damage, so I soldered those 2 wires together. But the problem still is there.
But, the strange thing is, if I drive with my 3S LiPo I haven't got any problems at all!


I really don't get it, could someone please help?

Thank you,

Patrick

[BrianG]

How many NiMH cells are you trying to use? And, have you disabled the LVC when using NiMH cells? The NiMH voltage may be dipping under load tripping the LVC or just dropping far enough that the ESC is "rebooting".

Originally Posted by BrianG

How many NiMH cells are you trying to use? And, have you disabled the LVC when using NiMH cells? The NiMH voltage may be dipping under load tripping the LVC or just dropping far enough that the ESC is "rebooting".

I'm using 6 cells nimh. So 7.2V... Yes, I have dissabled the LVC.

Well the ESC usually "stops/makes a pause" if I give full throttle a few times in little time.

[BrianG]

That makes sense. The on-board BEC also provides power to the control circuits. And BECs need at least 1v higher than their value (need 6v input if they are rated for 5v out). If the battery voltage drops low enough, the BEC is dropping low as well and is most likely rebooting the control circuits. This dip is happening long enough for the controller circuits to reboot, but not long enough where you'd notice any effect servo operation. Since it takes time for the ESC to re-arm, that is noticeable.

Possible solutions:

Running 7 cells should cure this.

Or just run 3s all the time.

Or, if you don't mind a loss in top speed, gear down a bit. This will pull less battery current and will not cause the battery voltage to drop as much.

Or, dialing in a little punch control should work too, but probably won't have as much effect as gearing down. But at least you wouldn't lose top speed this way.

Originally Posted by BrianG

That makes sense. The on-board BEC also provides power to the control circuits. And BECs need at least 1v higher than their value (need 6v input if they are rated for 5v out). If the battery voltage drops low enough, the BEC is dropping low as well and is most likely rebooting the control circuits. This dip is happening long enough for the controller circuits to reboot, but not long enough where you'd notice any effect servo operation. Since it takes time for the ESC to re-arm, that is noticeable.

Possible solutions:

Running 7 cells should cure this.

Or just run 3s all the time.

Or, if you don't mind a loss in top speed, gear down a bit. This will pull less battery current and will not cause the battery voltage to drop as much.

Or, dialing in a little punch control should work too, but probably won't have as much effect as gearing down. But at least you wouldn't lose top speed this way.

Ok, thank you for your explanation! That sounds logical...
I'll run 3S, and buy some pinions + spurs for my Rustler VXL...

Btw, I read the manual a few minutes ago, and I saw this: If I set-up the ESC. I've have to choose "battery selection", there are 5 options, 3 of them are LiPo blablabla and 2 of them are these:
- Ni-MH Normal "Select when the battery capacity and discharge rate are lower than voltage in use. Slower throttle response and lower torque than when Ni-MH High is selected"
- Ni-MH High "Select when the battery is compatible with the voltage in use. Faster throttle response time and increased torque compared to when Ni-MH Normal is selected"

Which one should I choose? My English isn't very good, so I don't get it what they're meaning, and more important, which of them should I choose?

[BrianG]

The "high" modes simply allow the ESC to pull whatever it needs to get it to run. But, you may need the best cells. The "normal" mode is a little more gentle on batteries. I like to run on NiMH "normal" or Lipo "manual" (and then set the LVC point to 3.0v/cell). There is a torque limit or punch control function (can't remember what it is called at the moment) that may help too.

Originally Posted by BrianG

The "high" modes simply allow the ESC to pull whatever it needs to get it to run. But, you may need the best cells. The "normal" mode is a little more gentle on batteries. I like to run on NiMH "normal" or Lipo "manual" (and then set the LVC point to 3.0v/cell). There is a torque limit or punch control function (can't remember what it is called at the moment) that may help too.

I'll try the NiMH normal tomorrow. I also run LiPo Manual and also at 3.0V/cell.

And because you also got a Quark ESC, you could probably answer this question to: In the manual it says "OPTO modification must be applied when using a battery pack above 10 cell NiMH or 4 LiPoly cell." Does this mean I can just drive with 4S LiPo and if I use 5S or 6S I should use a UBEC?

Just asking for safety, don't want to do something wrong to my lovely Quark (Yes I REALLY love that ESC)

EDIT: Btw, you've got 2 Quark 125B's, right? On how many volt do you run them, and in what cars?

[lincpimp]

Best to remove the red wire from the signal plug and run an external bec/ rx pack when using any more than 2s lipo. The linear bec in the quark will get quite warm with anything over 2s lipo, as it has to bleed off the addl voltage over 6v as heat...

Quark makes a great esc as far as software goes. I have 2 125b and 2 65 roadsters. I have had great use out of them, although they are a bit iffy on 6s. Work fine on 5s!

[BrianG]

I agree with linc; anything higher than 2s lipo or 7 cells, use an external switching BEC.

Yes, I have two 125's. One is in my Ofna Ultra GTP (road car) on 5s and Neu 1512 2.5d. The other is in my Hyper8 buggy on 4s and Neu 1512/2d. In both cases, I made a mounting plate that doubles as a heatsink. Works great, especially if you use a little thermal compound. These ESCs do tend to run warm otherwise.

Ok, I'll buy one directly. The ESC was also pritty hot with 3S today...

What about the CC BEC? This one: http://www.amainhobbies.com/product_...ducts_id/18210

Oh, and my Quark ESC already got that external BEC thingy, look at pic:

Which name do those things have/where can I get the other piece that should be on the external BEC?


Thanks,

Patrick