Feigao 7L, Warrior 9920 + 12 GP 3300 cells = hot?
 

Hi,
I've got this setup (Feigao 7L, Warrior 9920 on 12 GP 3300 cells) in a 1:8 buggy.
I get controller temps above 80C° (176F) and motor temperatures of about 80C°.

I wouldn't worry too much about this if nothing strange happened but I regularly lost control over the car.
Throttle didn't work at all and steering seemed to work sometimes, but without real power. Wheels turned some degrees on ground, lifted up they turned pretty slow.
Servo: HiTec 5945MG.

Do you think the reason might be thermaling or might the Graupner XS-6 have some problems?

I think it's the controller though since the problem seems to occur after driving for a minute or two and then regularly. After a short amount of time (ranging from seconds to a minute) the car is drivable again.

Bye,
felix

With normal 1/8 buggy gearing, the 7L motor is on the hot side if you ask me. The 10L is the better choice for that application. 176F is pretty warm on the controller(near the thermal mark), which is likely due to the hot motor. Perhaps you are thermalling and the temp drop below the thermal mark by the time you get a temp on it. If the throttle stops working, it is most likely a thermal shutdown on the controller. Add a fan and drop a couple teeth on the pinion (or get a slower motor for this application). The steering servo sounds like it is bad, based on your statements. Doe sthe steering servo work well at first, or is it slow from the start of the run?

Mike, your loosing it.. ;)

Give the guy a warm welcome..

Hi Felix! Welcome to this Forum!

Do you use the controllers BEC? what is your gearing end ratio? I guess the only gears that are on the car are ; pinion/spur and diffpinion/ringgear? and how much does your car weight? a good 8.5-9lbs?

I would use a motor in another kv range.

Hi,

the HiTec is fine as far as I can tell. It's working at normal speed and turns the wheels without problems while standing still. Just happens in combination with the throttle problem.

I knew that the motor is really hot, I didn't know that it's too hot. ;)

The buggy is a GS Storm, the new parts are made of carbon fibre.
Some pictures can be found here
http://www.cx4.de/rc/storm01.jpg to http://www.cx4.de/rc/storm08.jpg

Most of them aren't too good, but you get a better idea.

I'm using BEC and the pinion (module 1) has only 13 teeth. So that's pretty low already. The car should be pretty light, about 2.8kg without batts I think..

I'll try to get some more info about the gearing.

I did send a welcome private message, but your are right. welcome aboard, felix. Please pardon my manners. :)

13/46 is still too tall with that motor. It equates to a near 60 mph speed, which is a lot to ask of a 12 cell brushless setup. If your buggy weighs just over 6 pounds with the batteries, I will be impressed. I would guess closer to 9 pounds with batteries.

Mike has got a 12 tooth. (or even a 10, if you don't use a metal spur)

That spur looks rather small, but i might be wrong though..

No problem Mike, I got the private message. ;)

If the spur is the gear next to the pinion it's 48 teeth delrin I think.

I'm not really sure what would be the best way to solve the problem. Higher voltage would need a bec unit (more cables) or a receiver batt, a slower motor would be slower ;).

Would the MGM 120 help?

Changing the pinion might help, but if the 13t pinion gets the controller to 80C° in less than 2 laps it might not be enough to change the teeth count by 1 or 2...

bye,
felix

How fast do you need it to be! It should easily beat the nitro buggies with a 10 tooth pinion, and will run a bit cooler as well. 3 teth on the pinion will make a significant difference.

Dropping down to 10t would do something.

Problem is, I'm in Germany and if stuff gets stuck in customs it's a big hassle to get it.

Do you think adding a receiver pack would help?
Apparently the BEC in the controller produces some heat which could be the reason for my problem.
I don't like adding another battery too much, but it'll be interesting to check if it helps.

Get a UBEC! lightweight alternative!

Well, UBEC wants me to solder connectors to the batt cables and so on, we'll see.

Just found this:
http://cx4.de/rc/warrior1.jpg
http://cx4.de/rc/warrior2.jpg
http://cx4.de/rc/warrior3.jpg
http://cx4.de/rc/warrior4.jpg

Was looking for the jumper to deactivate the BEC...

I 2nd that! Get an UBEC. Might solve some problems.

Mike is very good at filling out the custom forms, by the way. Never had any problems with his stuff, and the swiss custom guys can be a real pain.

You got there first!;)

The UBEC is very easy to install, though.

Those pictures doesen't look to nice, man. Guess you found your problem.

Looks like an overload.. might be the regulator for the BEC that does this.. though your motor is way to hot for this setup..

Heatsink melts away pretty easy, but it might be damaged. (the controller)

Just checked the manual, it says the Warrior thermals at 110C°. ;)

Found a 10t Modul 1 pinion in a shop here, I'll try that one.

Can you give me some advice where to find the BEC jumper?
I think I found it a bit under the red jumper and caps. Pretty hard to find with the heat shrink on.

Ok, seems like I've got the right jumper.

Yeah, you need to strip a rather large piece of the heatshrink..

Hi,
finally got to testing the car with a receiver pack (and the correct screws in the diff ;). I actually mixed some of them up and put longer ones in there which made it quite a bit harder to push the car. Seems like the motor didn't really notice though.

The controller overheated pretty much as fast as before, now I measured about 95C° on the heatsink.
As expected steering worked normal during the cool off time now. I think the warrior just puts out less BEC current while thermaled. The heatshrink didn't melt this time.

I'm going to try a 12t (smaller won't fit in the chassis easily) pinion and active cooling next.

12V CPU cooler & BEC unit are installed now:
http://cx4.de/rc/storm11.jpg
http://cx4.de/rc/storm12.jpg
http://cx4.de/rc/storm14.jpg

I'm not really happy with the additional cables. ;/

The UBEC is a "nice to have" more than a "need to have" on 12 cells. The real problem is that the motor is too hot for the application/gearing, as mentioned before. In order for the car to get to the speed it is geared for, it draws LOTS of amps! This heats things up a lot and will significantly reduce the amount of cycles you get on your batteries. If you want your car to go 60 mph, use more cells and a slower motor and you won't have nearly the trouble you are having now. You will also get a better runtime. You could even use smaller gp2200 cells (18 of these would only be a little heavier than 12 of the larger cells) and you would get cooler running, a longer runtime and more power(with a slower motor of course). Adding fans to your current setup is kind of a band aid. It will work, and may even prevent the thermalling, but it only covers the true problem (too hot of a motor/too tall gearing).

I know that but it's not that easy to switch if you already have the stuff.. ;)

More sub-c cells won't fit and I'm not sure about 4/5 cells.
My old 4/5 pack (8 cells) seems to be longer than a sub-c stick-pack, as one would expect.
The battery holder is really optimized for 6 sub-c cells side by side.

At the moment I want to get the setup to work and maybe later switch to LiPo. This would make quite a difference in weight and/or runtime. 6s and a slower motor would help with the heat.
Not cheap and as durable though.

just a motor isn't terribly expensive to work with the stuff you already have. I think you could might be able to squeeze 8 gp2200 cells into the 6 cell battery space. It would be tight, but I think it may just fit.

Yeah, I think you should take Mikes advice and try a cooler motor. It will be worth it.

Just played around a bit and I think it will be really tight with a stickpack.
Maybe if I took off the end caps and resolderd the cables...

On the other hand a new motor + packs would easily get to 300€. I would rather use the 12 cell setup until the cells die and then buy lithium and a new motor.

Another option would be to go with less speed and put a 9L or something like that in there.
Do you have an Idea how much speed I would lose with a motor that's appropriate for 12 cells?

On paper, you would lose a bit of speed, but in real life,. you won't lose nearly as much, as the cells would hold higher voltage. The 9L or 10L would still get you over 40 mph (still handily beat a nitro buggy on a race track, and would be close in top speed). The 10L would get you near 40 mph, while the 9L would get you into the mid to upper 40s.

You may actually end up with the same or better speed, in reality, as I am sure your batteries are dropping serious voltage with the load you are putting on them. You may get better runtime and speed in the end simply by swapping motors.

Heh, well that would of course be perfect, better performance and more run time. ;)

Do you know which of the Wanderer 20s is best, 9L, 10L or even more winds?

10L would be my choice. The 9L would also work. I can get the wanderer motor direct shipped to you from BK, if you are interested (this way, you become one of my customers, but get your products shipped direct from BK and avoid the customs as if you bought direct from them - a rather nice arrangement I have with BK). I can quote you a price through e-mail or PM on any motor offered on the BK site.

What would be your prices for the 9L and 10L?
PM or email would both be fine.

80 dollars round..

Look here

I got a 9L today and it works fine so far. Had to put new plugs on the controller, which isn't fun if you have 2 cables from the controller to put into 1 4mm gold plug.

The strange thing was that everything went crazy when I tried to accellerate, steering started to act up and it accelerated and braked by itself. After quite some playing around I found out that it does this if the receiver is mounted on top of the Hitec servo (which worked for weeks) or if I touch a screw with the receiver.
For now I put a folded handkerchief between servo and receiver which seems to help. Only on fully throttle there's some wiggling of the front wheels (maybe normal?).

Glad you have it up and running, but the glitching you described sucks. I never had any glitching, just make sure everything is well insulated. Antenna and receiver. I'm sure you can work this out. Otherwise Mike, me and the boys here will help you to find the cause.

What are you running for BEC. A batt pack or a UBEC, or do you use the internal BEC of the controller?

How do you like the motor so far? Speed and acceleration?

I had the problem with a bec unit, receiver pack and the controller's bec. I went back to internal bec now since it's the simplest way.

Maybe I'll try to put in another servo to see what happens.

I haven't had time to test the car with the 9L yet, maybe I'll be able to test it in the track tomorrow.

Hmm, sounds strange. I never heard of a servo producing a glitch.
I hope you can get this worked out. The motor ran well in my Twinforce.

For 12 cells, the internal BEC should be perfectly fine I have used mine up to 22.2 volt Lipos with no trouble!). Also, it is fairly common for a servo to cause a glitch, believe it or not.

As in Servo glitches, or as in Servo makes ESC glitch, or both??

Both.

OMG. Do you americans know the saying: Knock on wood. ?

Are there some common ways to deal with it besides getting a new servo or relocation the ESC?

The internal BEC seems to generate at least some heat. When I used the 7L with internal BEC the heatshrink melted where apparently the BEC is located but then the controller was overheating regularly anyway.
I hope that it runs cool enough with the 9L so I don't need a fan or external BEC...

Put a barrier between the servo and the controller, such as a couple layers of mounting tape, and keep the antenna shielded as well (fuel tubing between receiver and the antenna holder for example).

I don't know if anyone has noticed this, but I have found the Warrior to be a "noisy" controller. As in it produces quite a bit of interference. With my 9918, I can only get about 150ft of range with a 75mhz FM radio. When I had my MGM (it's being serviced), I could easily get 300ft, which at that point I couldn't see the car very well anymore. And this is when using an external BEC with the 9918 and the MGM's internal BEC.