Crt.5 brushless overheating
 

IM BACK FROM PLAYING FOR AROUND 10 TO 15MIN WITH MY CRT.5 AND THE TEMPS WAS :

177F ESC

157F MOTOR

100F BATTERY


IN A OUTSIDE TEMPERATURE OF 18 ºC = 64.4 ºF

I DRILLED HOLE IN THE WINDSHIELD..

I PUT THERMAL GREASE BETWEEN THE MOTOR MOUNT AND THE MOTOR ...

THE CENTER DIFF WAS FILLED WITH 120K FLUID..

NOTHING HELP !



SPECS WAS :

MAMBA MAX 1/10 ESC ( BEC ACTIVATED )

NEU 1509 2.5D 2700KV

13T PINION

46T SPUR

3S LIPO TRUERC 15C 6400MAH ( I TRIED A ZIPPY 3S 5000MAH 25C TOO )

SURE IM USING BIG TIRES AND BIG BATTERY ON MY CRT IT WEIGHT AROUND 6LBS..

Differential Ratio: 3.25
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 46
Pinion Tooth Count: 13
Total Voltage: 11.1
Motor KV: 2700
Tire Diameter (inches): 4.72
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0.0082
Spur/Pinion Ratio: 3.54 : 1
Total Ratio: 11.5 : 1
Tire Circumference (inches): 14.83 inches (376.64 mm)
Total Motor Speed: 29970 RPM
Vehicle Speed: 36.59 mph (58.78 km/h)
Effective KV Value: 2700
KT constant: 0.5 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...

Any binding or loose solder joints? It looks like you're geared about right... What kind of driving was it? Hard offroad?

3S Lipo MM = BEC and extra cap... temps will drop v quickly

battery temp looks good, motor temp is a bit higher than expected but still safe, esc temps I'm sure are mostly due to running 3s without an external BEC, as already mentioned

Your truck is really heavy too. What do you have on there that makes it so heavy? Just the tires?

Try an external BEC, I think it'll help you out a lot.
I just tried the speed calc with my current CRT.5 setup with some 4s Lipos. 45mph! I might need a gear down some if the MM starts to cook.

I will try to power my receiver with a 6v aa pack then but why I run my traxxas slash on 3s with the integrated bec without any heating issue ? and got issue with this one..

Depends on the current draw from the servo. The Slash may have less weight in front, so it takes less power to turn the wheels.

And depending on your slash, you might not have as much amp draw on the motor either.

do ya think this extra cap would help alot ? :

http://www.rc-monster.com/proddetail.php?prod=35vcap

and do I need to solder it on the esc board or solder it on the esc battery wire can do the same thing ? and more easy to solder ..

:neutral:

An extra cap will do little to help overheating on the BEC.

only one extra cap not 2 ?

and if the motor heating up does the esc heating up too ? and vice versa if the esc heating up the motor heating up also ?

I looked back at your original post and noticed you have 4.72" for the tire diameter. Are you sure that is right, it looks awfully large for a CRT.5. 1/8 scale buggies are around 4.25" IIRC.

http://img139.imageshack.us/img139/121/photo00667.jpg

why not ? :wink:

Wow, I see.

Well, I'm not sure about what cap you are wanting to add.

Do you mean a "glitchbuster" cap to help the BEC cope? If so, that won't work; all it will do is help even the load (smooth out the current spikes). And with tires that big, there is quite a load on the steering servo and BEC. Plain and simple: you need a switching one.

Or, do you mean extra caps on the power lead to augment the existing 3 caps on the ESC? If so, that may help (certainly won't hurt), but I wouldn't expect miracles.

I think your best bet would be to get a UBEC and possibly gear down a tooth or two. A 2700kv motor on 3s is only ~29k rpm, which a bit on the slow side. The ESC may simply be pulling a decent amount of current to retain 35mph speeds. With that motor and tire size, I'd go 4s and gear to 11T or 12T on the pinion. But at 4s, a UBEC is required.

Yes I talk about a extra cap 1200UF/35V

what happened if I used heavier diff fluid on the rear diff then the front diff ?

http://richtechparts.com/i-2564-1200UF_35V.html

do you think these one are low ESR ?

Probably. The 105*C temperature rating is usually low-ESR. The regular style caps are usually rated for 85*C.

ok good!

it is possible my 4.72inch tires with the balloning factor goes up to 6inch ? and the speed at 4.72inch are 33.67 mph (54.08 km/h) and with the ballooning the speed goes up to 51.93 mph (83.41 km/h) ...

Could very well be.

im back from playing with the crt.5 and I have strapped the GPS the top speed was 39.37 mph (63.25 km/h) the runtime with a 3s 6400mah was 32 minutes I runned 13.2km ( kilometers ) in total.. the outside temp was 13°c ( 55f ) and at the end of the run the motor was 95f and the speed 95f too no body in it and bec disabled ...

anyone can diagnostic my amps draw from this info ?

and for my rx pack I used 425mah for 32minutes of runtime

so with a bec or not it wont really affect the runtime on the main battery I think ... maybe only around 2 minutes ? :smile:

rx 425/32*60=800mah = 0.8amps

Bat = 6400/32 *60= 12 amps