# Havoc 3S Cutting Out - Help??



## BSRBOY (Nov 11, 2009)

Here's the setup:

Losi SCT
Havoc 3S
13.5 Ballistic Motor
8.5 Final Drive Ratio

I'm running Duratrax NiMH batteries. With a 2500 mAH NiMH 6-cell I would lose throttle control periodically while racing. (Motor and ESC temp are WELL within normal limits). For instance, full throttle down a short back straight, hard brakes to slide through the turn, then as I get back on the throttle the ESC cuts out. 

On my 2nd run I switched to a 7-cell, 3000 mAH NiMH Duratrax pack and the problem disappeared.

Could it be that the cheaper (lower voltage) packs aren't capable of keeping up with the motor/ESC power draw? Or could this be an intermittent electrical problem?

I checked the power / sensor leads and everything looks ok...


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## kevinm (Jan 16, 2002)

You've probably got the LiPo low voltage cutoff turned on. 6-cell Nimh batteries can easily drop below the 6.6V (probably) threshold.


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## BSRBOY (Nov 11, 2009)

No, the cut-off is turned off.

I called Novak and their "best guess" (since they didn't have anything definitive to say) was that the battery voltage could be dropping so low (the 6-cell that is) that the ESC is almost shutting off.

Either way, the 7 cell pack solves the problem for now, so I'm all set.

This IS a common problem based on my google-engineering...


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## tmaxx4life (Oct 23, 2008)

im gonna say that i had a 3700 nimh batt and it would cut off intermittenly and it turned out the battery was going bad interally in one of the cells. go lipo save the hassles of old technology its getting cheaper to get them now www.hobbypartz.com


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## BSRBOY (Nov 11, 2009)

So things got complicated today.

I bought 2 new Traxxas 8.4V 3000 mah packs - they tested fine on my Turbo30. Go out for one run and the ESC does its little cut-out thing only once.

Go out for a second run and the ESC fan isn't running at full speed, making some ugly noises. So I unplug it and figure "how hot can this thing get anyway"?

After a few laps the truck starts stuttering - BAD. So I pull it off and the heat sink is pretty warm, about 90 F if I had to guess. I fussed with the fan but couldn't get it to run correctly. At this point I tried another lap or two and the cut-out problem was too bad to drive so I called it quits.

There's no way that the batteries are the problem. The Traxxas VXL systems is faster than my 13.5 system and runs the same, exact, batteries.

I think I might just pull it out of the truck and send it to Novak for a checkup. I got it on ebay so who knows what the last idiot did with it.


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## ta_man (Apr 10, 2005)

I've got one possibilty for you: The servo may be overloading the BEC.

I had this happen to me on 3S and while I realize you are not running 3S LiPo, it is still possible that the servo is overloading the BEC.

I eventually confirmed my problem by turning the wheels left and right with the front end in the air - in about a minute the ESC overheated and shut down. The Havoc 3S BEC is not as strong as the ones in Novak's 2S controllers.

I looked at your posts and couldn't find anything on what servo you are using. Try the test where you steer left and right fast with the front wheels in the air. If it starts cutting out, your problem is that the servo is overloading the BEC. It could be a bad servo, one with intrinisically high amp draw, or a problem with the BEC. If it starts cutting out, try a different servo, maybe an analog one not known for high current requirements (like a standard Futaba servo if you have one).


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## BSRBOY (Nov 11, 2009)

Hey Ta-Man. Thanks for the post.

Unfortunately, I'm only running a Futaba 3003 servo. I've had it in the truck since day one and haven't had issues until now.

I also had the steering apart at the same time I put the ESC in and made sure everything was free and wasn't binding...

Time to call Novak. I'll let you all know what they say.


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## BSRBOY (Nov 11, 2009)

Well, I talked to the tech at Novak today - he was just as stumped by my problem as I am. Even though the 3S is more suited for light duty (buggy, touring car, etc) he said it should have NO problem with my XXXT-SCT. In the end, he recommended sending it to them to take a look at.

Whatever happens I'm going to install a new sensor wire with the new ESC. Hopefully the problem will be gone by then. If not the only other thing is the motor! Which I think is unlikely because the Ballistic motors are stout.


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## hockey1994 (Jul 7, 2011)

BSRBOY said:


> Well, I talked to the tech at Novak today - he was just as stumped by my problem as I am. Even though the 3S is more suited for light duty (buggy, touring car, etc) he said it should have NO problem with my XXXT-SCT. In the end, he recommended sending it to them to take a look at.
> 
> Whatever happens I'm going to install a new sensor wire with the new ESC. Hopefully the problem will be gone by then. If not the only other thing is the motor! Which I think is unlikely because the Ballistic motors are stout.


Does it cut out or cog coming out of the turn?

I had cogging problems with lipo batteries with two separate brushless systems, but not with nimhs, novak suggested I replace the rotor magnet. It stopped cogging for a while, but eventually started again. So I just run nimh's. Because you bought the setup used the previous owner may have overheated the motor causing the rotor to lose some magnetic strength. The rotor replacement cost is about $30.


Also I had a more recent problem with cogging which simulated the motor was over geared, but it ended up the antenna wire was hitting the graphite chassis.

Basically i'm saying it could be one thing or multiple things, but I would start with a rotor.


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## BSRBOY (Nov 11, 2009)

Definitely not cogging. I know what cogging is - this is a total shutdown of any throttle response. Only steering remains.

We'll see what happens when I get the new ESC.


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## hockey1994 (Jul 7, 2011)

BSRBOY said:


> Definitely not cogging. I know what cogging is - this is a total shutdown of any throttle response. Only steering remains.
> 
> We'll see what happens when I get the new ESC.



When the truck shuts down try moving the sensor wire around, sounds like you have an intermittent connection. I have also had similar problems where the sensor wire broke off of the JST ZH connector on the ESC side. Resoldered the wire to fix that problem. Also had problems where the JST ZH connector became distorted also on the ESC side and the ground wire became intermittent. Had to replace the whole harness to fix that problem. These things are very small, you might want to use a magnifying glass. 

The other thing it could be is your battery pack might have a bad solder joint. Try flexing the pack while a volt meter is connected to see if the voltage drops out.

Good luck


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## BSRBOY (Nov 11, 2009)

I'll admit I haven't tried a new sensor harness - though I do plan on installing a new one with the new ESC.

It's definitely not the battery because it's done it now with several different packs.

Bottom line: I got the ESC off ebay and the guy selling it probably knew damn well that it had issues. I sent him an email and guess what? No response.

Live and learn. From now on I'll buy my Novak stuff brand new.


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## ThrottleKing (Feb 13, 2008)

Are you using a 2.4 system. I have seen some cut out the throttle only but still have steering and the the cause is a multitude of things, BEC is poor, high vibration, failing servo, poor wiring/ routing, Loose connectors. Bad sensor board in motor could also do this. Check with different servo, double up on tape for the receiver. Check the ESC switch if its the one that you program with( seen that issue too) Do the one touch just to be certain. and if all else fails send the esc and motor in for a checking if your motor is an SS it's probably ok as I have only seen one fail from too high of heat and a blown up rotor. Good luck to you.

Jeremiah Ward


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## BSRBOY (Nov 11, 2009)

Wow that was a lot of comments in one post. lol

I ohm'd out the sensor wire today - doesn't seem to have any poor connections.

The Havoc showed up @ Novak on the 30th. I should have the new one by the end of this week I would think.


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## BSRBOY (Nov 11, 2009)

A number of you guys were following this so I figured I'd close it out...

Novak ended up sending a new esc to me to replace the Havok. I was actually shocked because I had changed the plugs on it and they could have said "you're on your own" if they wanted to. So now I've got a new Navok Pro SC to toss into my truck.

I wanted to take this opportunity to praise Novak and thank them for their support. They communicated through the whole process and stood by their product. I've looked at other ESC manufacturers before - even Hobbywing (GASP) - but after dealing with Novak and their excellent customer service, I'm going to stick with them. The best RC products are designed and made in the U.S. and I plan on supporting those companies.

Thank you Novak!


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## 4ThePinkRacing (Apr 30, 2010)

so was that the issue ?? the ESC ? ..


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## BSRBOY (Nov 11, 2009)

Apparently, yes. The only other possible solution I came across was the steering servo lugging the ESC from a steady draw (it was happening on a big sweeping back straight). The quick fix for that problem is adding a power capacitor evidently - but we'll never know...


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## 4ThePinkRacing (Apr 30, 2010)

i might be wrong on this but .. the capacitor on the plus n minus wires .. from the battery .. does nothing but smooth out the voltage .. and filter noise .. 

on the radios i use we put them in cars to get rid of the noise in the stereos when you use say a CB or a Ham radio .. samething as the ESC idea .. 

but i could be wrong .. but i see nothing else it can do ..

but all is good .. novak i have to give them credit .. i havent had any issues with them .. i call up talk to them on an issue with a product of theres .. and they r more then happy to help .. and fix the issue even if its sending out replacement or free stuff .. 

i got to say hats off to novak .. customer service is awsome .. now if they just lower the price on the kanatic lol


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