silversurfr77

Hi everybody, this is my first time here. Just purchased a Tamiya kit for a crawler, and I'm a little stuck. Rather than going into individual categories, the club house seemed like a sort of general discussion forum. I was hoping I could get some help on electronics here.

the kit came with a 540 brushless motor. I'm trying to figure out what kind of ESC I need. Many of them refer to how many turns? but I am a complete noob and have know clue where to find this information. If anyone wants to help I have The CR-01 Rock Socker kit. I just found 2 futaba s3305 servos on ebay and they are on the way.

Another thing that I was unsure about, my local hobby centre has strongly recommended that LiPo batteries are the way to Go. The servos I purchased say nickel-cadmium only, but Tower Hobbies info section on my servos says that I can run LiPo's, but to check the output. Don't even know where to begin there......

Trying to put this puzzle together, but the language is Greek to me. If anyone wants to help, I would be much obliged.

AMA 74894

My Feedback: (1)

I'd post the question in the rock crawler forum, with a few IMPORTANT notes.. I googled your car kit, every one I've seen shows that it is a 540 size BRUSHED (NOT BrushLESS) ESC.

EASY way to check: a brushed motor has TWO wires, a brushLESS motor has 3 wires. (ESC's and motors are NOT interchangable... a brushed motor must use a brushed ESC, brushless motor must use a brushless ESC.)

Tower carries that kit as well as the ESC, etc. I would call tower and let them know what you've got and what you'd like to use. (they show a nicad battery pack, I would ask about using the recommended ESC with a LIPO battery)
(below is the link to the required accessories for your crawler.)
http://www3.towerhobbies.com/cgi-bin...I=TAMC8592&E=N

good luck!!!

silversurfr77

Hey thanks for the reply. As a mod I'm sure you can move this thread to the crawler forum. I am still very new to the site so I apologize for posting in the wrong place.

I did go to my local shop and ended up getting the right ESC....and yeah, I did realize the motor was brushed in the nick of time

I did notice the 2 wires, but strangely enough......the plugs on my tamiya motor are green and yellow......not red and black as is on my ESC. Which is positive and negative?

AMA 74894

My Feedback: (1)

the wire colors aren't important, you can plug the motor wires into the ESC either way. if the vehicle goes backwards when you command forward, swap the wires
(GOOD catch on the esc!)
I'll move this post to the car /rock crawler forum. Good Luck and WELCOME!

nitrosportsandrunner

onto batteries....
Lipos are better, hands down. Lighter, more powerful, usually longer lasting.
However, their biggest advantage may be their amp output. They can supply energy faster. This is important with fast models, race vehicles ect.
But, a rock crawler is generally slow. So, I high output battery isn't a big deal.
Example:
I have a 5000mah battery for my sc10 race truck (mah refers to capacity) and it will run for 25-30 minutes on a charge.
I have a 4000mah battery for my 1/6 scale custom hummer rock crawler. It is a MOA rock crawler, so it actually has 2 motors. It can run for 1.5-2 hours on a charge! Both batteries are the same voltage, but the rock crawler motors draw much less amps so the battery lasts much longer.

Reasons not to get a lipo:
if the ESC you got isn't lipo ready. Lipos cannot be fully drained like nimh packs. The ESC that is lipo ready detects the voltage of the pack and cuts power to the motor when it is time to recharge the lipo.
Cost. while some lipo packs actually don't cost more than nimh, you have to have a lipo specific charger. The least expensive are around $50. They can charge lipo, nimh and other types of batteries.

reasons to get lipo:
generally longer runtimes.
lighter than nimh
they usually last a long time, even if you go a couple months without using them.
more voltage....a 6cell nimh is 7.2v where a 2 cell lipo is 7.4v (8.4v when fully charged) and a lipo keeps its voltage up until it is time to recharge, instead of slowly draining and lowering its output like a nimh pack.

I personally have never had or seen a servo that couldn't run on a 2s lipo battery. the voltage is soo close to a standard 6cell nimh....plus, the receiver is what supplies power to the servo and this is usually limited to no more than 6v.

long and short of is...since you are new, go with a nimh pack. once you have had fun with your truck, learned how to work on it and how your other electronics work then you can upgrade to a lipo. The CR01 will certainly do just fine on a 6cell nimh battery.

silversurfr77

Great info on the batteries. Thank you. It took me a while to figure out the voltage situation. These types of comments are great! As I stated this is all new to me, and the language as well.

I was very confused when trying to understand servo/battery voltage compatibility.

So far I have all the components (I think) I need to complete. The radio is on its way. When assembling I had the option of locking the differentials. Can anyone explain the significance in doing so on a crawler?

And lastly......honestly......what's better? Going fast or playing with a crawler?

nitrosportsandrunner

locking diffs....
with the diffs open, power will always go to the wheel with least resistance. So, if your front right tire is off the ground and the left is on the ground, power will go mostly to the right tire.....so your front axle wont be able to pull the truck. If 1 rear tire and 1 front tire are in the air, then the truck will hardly move as all the power will go to the wheels not touching the ground.
Open diffs make turning easier, since the inside and outside wheel can turn at different speeds.

Locked diffs means power ALWAYS goes to both wheels on a axle and they always turn at the same speed. The greatly improves crawling ability as you can have 1 tire in the air and the other tire and that axle will still be working to move the truck.
locked diffs reduce turning ability some, as the front tires will always turn the same speed. the truck will still turn, just not as tightly.

A compromise is to lock the rear, and leave the front open.

there are videos from chevy showing there g80 locking diff in action.... a truck on a hill where one tire is basically off the ground....at first the truck wont move...then when the difference in speed between the 2 tires is high enough, the locking diff locks and power now goes to the tire that is on the ground and the truck gets moving again.

basically, with open diffs a 4wd truck can still get stuck as it can become 2wd (1 tire on front and 1 tire on rear in the air, or with no traction spinning and the other 2 tires not getting power)
A 4wd with locked axles sends power to all 4 tires all of the time and they all rotate at the same speed.

locked for lots of rock crawling. locked rear, open front for trail driving or more challenging mild rock crawling. Open diffs if you want to drive it around like a monster truck that can still go threw some mud or sand or other loose surfaces.

I enjoy rock crawling and driving fast the same. rock crawling is more technical....where you place the tires, picking the right line and such. Throttle control is important as well, to much or too little can result in either the truck not moving, or the truck possible breaking something.
Driving fast can be a handful that can require fast reflexes. And jumping an rc is always fun.

some people give rock crawling a try and don't like it. Often, picking the right place to crawl is important. the right mix of rocks, loose surface, maybe some water or mud will make driving your crawler more fun. Drive where the rocks are too small or way to large and it can be to hard or to easy to drive. Some also try to drive crawlers as fast as they can....this will lead to lots of broken driveline parts. A tire can become jammed between rocks sometimes, punch the throttle hard and stuff can snap. It is more about control and watching all 4 tires and overcoming that obstacle that was a challenge.
Another aspect of crawling that is a huge draw is building your truck to look like a real truck. most fast RC's only somewhat resemble a real vehicle. But some rock crawlers are built with amazing bodies and amazing scale details.