My CRT.5EXT...;)

Hi guys, I finally got some time to get some pics of my BL CRT.5EXT or is it CRT 1.0? Sorry theres alot of pics!

Specs:
RC-M motor mount Geared 14/46
Custom battery mount
Gorillamaxx battery strap
Proline 2.2 Bow-ties
Traxxas stampede front wheels
Original Jammin full size CRT wing that was modded a little...

Electronics:
Feigao 10L motor with RC-M heatsink/clamp
TrueRc 4200mAh 4s (15c cont.)
Temporary Futaba 3004 servo.
Futaba FASST
UBEC from TrueRc (unsure on the brand)

So far thing runs awesome!

PICS:

Some more...




Getting ready to take the monster triple at the RC-M Bash...


Bye

[2FastSS4U]

Cool Beans! Love the table too, looks exotic :-D

[phildogg]

truck looks great bro..
phil

Thanks for the compliments guys.

Question, before I was running 3s and geared for 38mph and pulled 90amps. Now running 4s re-geared for 38mph I get a little over 90amps. Shouldn't I pull less amps? I am pulling more watts though; from 700 up to 1200+...

Heres a graph; Batt holds 3.375v/cell@ 90amps! Its 15c cont. which is 63amps, 20c burst which is 84amps, so I thinks thats pretty good!... @65amps I get 3.575v/cell


So why didn't I get a reduction in amps?

Bye

[lincpimp]

I think your findings illustrate what Brian is always telling me. With higher voltage input more amps will be drawn, up to a point. Not sure when this stops, or what it all means. I have a feeling thyat you had your 10l geared high on 3s and it was pulling 90amps due to heavier load. Now it is geared down it still pulls the same or more amps, but is most likely more effecient and may heat up less? The lower gearing will help the heat issue, it did for me when I went to 4s on my 10l.

Originally Posted by lincpimp

I think your findings illustrate what Brian is always telling me. With higher voltage input more amps will be drawn, up to a point. Not sure when this stops, or what it all means. I have a feeling thyat you had your 10l geared high on 3s and it was pulling 90amps due to heavier load. Now it is geared down it still pulls the same or more amps, but is most likely more effecient and may heat up less? The lower gearing will help the heat issue, it did for me when I went to 4s on my 10l.

Seems logical, With 3s I was geared with a 20t pinion, same as your crt.5 you had right? I get the same temps on the motor (145f) but the esc and batt are much lower(like 30f lower). So????????????????????????....Maybe Brian could chime in?...

Bye

[lincpimp]

Yeah, the motor temps on feigaos suck, you have to gear down to get them to stay low on a long run. The batt and esc are not working as hard now as they were on 3s with the 20t pinion. Plus the motor has greater mech. advantage with the smaller pinion gear. Som educated spouting by Brian would be nice!

[MTBikerTim]

I wish people would stop posting about these CRT .5 because I CAN'T AFFORD ONE.

I think if you you want to get lower amp draw you must put in a higher turn motor along with the extra cell. You should then get similar performance with a little better efficiency.

[2FastSS4U]

What's the largest size Neu motor that will fit in these things and will run well off of 3S with a Quark Monster Pro?

Originally Posted by 2FastSS4U

What's the largest size Neu motor that will fit in these things and will run well off of 3S with a Quark Monster Pro?

Well, a 1512 would be nice (around 2600-3200kv).

I'm thinking of putting my Neu 1515 1y in the crt.5ext. Question, would I effectively lower my amp draw because of the lower kv or just pull more amps because of it being a bigger motor?... I pull about 125amps and 1800+ watts(on 4s) out of my revo with this motor so???????...

Bye

[2FastSS4U]

Wow, that would be insane. I wonder if this would be a good platform to use in the next RCCA world speed contest. If so this may be next on my list.

[jnev]

Very nice truck. Man... I wish I could have been there to see the CRT.5 fly over that triple. Now that would be a sight to see.

Hey guys! I have a couple of questions on how to lower my amp draw in my crt.5ext.

Specs:

initial setup:
Maxamps 3s 4000mAh w/Feigao 10L geared for 39mph = 90amps (max) and 800 watts

Next:
Truerc 4s 4200mAh w/Feigao10L geared for 39mph = 90amps (max) and 1200 watts. Now, shouldn't I have lowered my amp draw?

After:
Truerc 4s 4200mAh w Feigao 9xl geared for 40mph = 100amps (max) and 1300 watts.

Now, I would like to lower my amp draw to about 60amps (max) if that is possible? What motor would do that? Pretty much my reason for going to 4s (besides the raw power) was to lower my amp draw to put less strain on my lipos. (at 100amps the voltage drops to around 3.3v/cell, my lipos are rated for 63A cont. and 84A burst) So, ?????????????? help would be appreciated!

Bye

[MetalMan]

If you could find a motor like a Feigao 12L or something like that, then you could lower your amp draw on 4s.

The problem with changing gearing to maintain the same top speed when increasing voltage with the same motor is that the motor's resistance is still the same. V = IR, and so since the resistance (R) is the same, when volts (V) increases, so does current (I).
Changing the gearing just means the motor won't pull as much current as if you kept the same gearing when increasing the voltage, but since it's still the same motor, the motor is capable of pulling more current.