Jeff burns

iTrader: (5)

I've always had nitros and this is my first electric car in many years. I just picked up a 3305 servo and Tekin TT2301 RX8 gen2 Tekin TT2500 PRO4 4600 KV Combo Package. I still need some batteries, charger and a radio. I got to tell you with the brushless and lipo equipment it seems like trying to solve a rubics cube to me. I was hoping to get some smc batteries but seems like there out. Can I get any suggestions or alternatives. will the smc rec. Packs fit, also I plan on getting a 2nd truck so my kid can run at the same time so possibly a little help with a charger that could charge these packs fairly quickly. I'm kinda hoping someone could confirm the esc motor combo is the right fit for this now that i aready decked out the money on it and do I need the hot wire box.

tfrankito

iTrader: (26)

your rx8 and pro4 will be plenty. Batteries. SMC 7200, I like the turnigy ultimates 7600 my self...only down fall is the 5mm bullet plugs. Me personally I need at least 7200 anything less and I run the batteries down to much for my liking. There are other batteries but how much do you want to spend? Charger..a dual charger at least 5amps per side will be faster 10 amp is ideal for a quicker charge. Orion dual, icharger is a great one. I use a thunderpower dual but I also charge 4s batteries. Depends on your budget really. but your electronics are going to be fine. for your son you could get away with the tekin 4300 or get the hobbywing set up sct pro and the 4000 and he will never outgrow it.

Josh L

iTrader: (1)

I run the box stock pistons and 6 hole 1.5's depending on the grip, and yes you will get better performance from going lighter on oil in loose situations. Generally this will always be the case, unless you run an over drive setup with the smaller rear diff ring gear which will allow for a heavier center oil, since the rear end acts sorta like a drag brake for the back half on and off throttle.

This is exactly the opposite in my experience.
The losi tends to be more at home in high bite scenarios, while the tekno tends to groove into a track that is loose much better.
If you are having issues with these things there are a few things to consider outside of just roll centers, shocks and tires. But definitely start with those things!
Outside of those, sending some of the chassis weight rearward can help with rear side bite loss by doing the battery tray mod, where you set the battery back further against the rear diff block. There is more info in this thread on it, just search it if you need further explanation, or maybe someone will post you a link if they know where it's at in the forums.
Also keep in mind that "slip angles" (rear toe relevance to front tire moment) and "akerman" (the difference of inside to outside turn in angle) plays a huge role in how your vehicle will rotate around a turn.
If you are a driver that likes to power through a turn, you should induce more ackerman by changing your drag link position. Inducing ackerman also tends to helps prevent rear side bite from breaking traction as easy, however you will lose initial turn in snap and potentially generate an off power push if over done.
Reduced ackerman (wheels turn in closer to the same degree side to side) will give more response, but can also generate push on power if your heavy on a trigger through a turn.
You can also put more weight on the rear tires by spacing the rear hubs more forward, effectively reducing the wheel base a few mm.
By reducing toe in on the rear, you will also open up the slip angle some more, making it easier for the truck to roll around a turn, reducing push.
Just remember there is always a trade off in on-power stability down a straight when you reduce rear toe. It will gain more forward traction, but its no good if it becomes unmanageable per your driving preference.
You also need to remember to find a new front toe degree each time you make such a change. Front toe always needs to be re optimized when you change such things, or the effect desired will go unnoticed by the new problem presented by neglecting that fact.
I wish I could be more definitive on my suggestions, but it's nearly impossible without being in person when your testing. Something as simple as a tire change could be the answer, or it could be much more complex changes! The only way to find out is lots of trial and error, and preferably with a person that understands all the factors involved and can identify things on the fly.
Just some food for thought.

Yes you could think of it like that. Heavier center diff will throw more power to the rear end, which will help kick it out if you like that effect and know how to manage in the loose and rough.
Alternately, increasing rear diff oil will act more like a locker the heavier you go, which will allow the outside wheel around a turn to get more power, which will also kick it out more on-power.
When playing with rear diff weight, you need to consider how tight your track is and how much forward traction you'll have around the turns. If you have a track that requires more mid to off-power turning, loose or dusted, you are going to want to keep it light so as not to generate to much outside-tire drag in a coast, preventing to much push as well as to much on-power kick out.
I generally pay more attention to the off-power side effects if going heavier till I find a happy medium I can live with and still provide proficient on power drive.
Ideally, you want to start light and go up till you don't like how it feels off power. It's easier than starting heavy and going down in that way for me.

Get a cap pack on there ASAP! 2S high KV combos tend to cause massive ripple/noise which can generate a lot of heat in your batteries and ESC, eventually killing your system.
Cap pack

You should consider checking out some of the 8000mah packs from RCJuice. They are cheap and are really nice packs for the cost.
My suggestion to you is to avoid the bullet connector types, in favor of pre wired packs. Bullet style packs generate to much heat on heavy hitting 2S SCT setups at the terminals and make reversing polarity to easy to accidentally happen.
Their shipping and customer service is one of the best in the business to!
hobbystar 2S 8000mah 100c

As far as a good charger goes, you might want to have a look into the cellpro powerlab 6 chargers. They are not overly expensive and their capabilities are second to none in my experience. These things will tell you everything about your batteries and can charge upto 6 6S pack at one time, provided you have a large enough PSU to feed it!
But realistically you will never need more than 12v @ 500 watts for 99% of the applications with RC cars.
Powerlab 6


You can get an inexpensive but reliable power supply from Ebay that is a converted redundant PSU core.
I made my own from one I bought from Amazon for $14. But if you would rather skip the head ache of researching how-to's just grab one here>
12V 75Amp 900Watt PSU

Jeff burns

iTrader: (5)

I just wanted to make sure i got the right motor. It's my understanding I can adjust the esc to tame the motor some to make the truck a little more manageable on smaller tracks. I've been trying to read up as much as I can to try and figure out the new terminologies and systems. My worries I guess are if I'm going to have 2 trucks going at once I just don't want to be be staring at the charger the whole time I'm out. In general what are the charge times for a 2s 7000mah bat. On say a Hitec x2 or comparable. Is going big on something like tp820 overkill for keeping a handful of larger 2s bats going. You have to excuse me for the basic questions just trying to avoid some pitfalls.

Jeff burns

iTrader: (5)

OK from what I can tell the powerlabs are top notch so going with a charger that big or comparable is the right move. I figure on using the dean's connectors. Oh my now I have to research cap capacitors.

Jeff burns

iTrader: (5)

I been figuring on going that route but that one looks to be a little better deal then I've been seeing

szymanski2oo1

"Get a cap pack on there ASAP! 2S high KV combos tend to cause massive ripple/noise which can generate a lot of heat in your batteries and ESC, eventually killing your system."

can i ask whats a cap pack? where does it go? do you mean a glitch buster that plugs into the receiver?
cheers

Josh L

iTrader: (1)

Haha, its ok man. Anyone that was out of the loop during the shift from brushed to brushless motors, to lipo batteries always has to take a minute to get their bearings back!
I was one of those people so I know how you feel!

Getting a good charger is always a good idea for multiple reasons, but the best reason is because you can count on accurate information and feed back on your packs. Cheaper or less tech savy systems keep you in the dark when it comes to such.
Cellpro or Junsi are on the top of the food chain and you will likely not need a new system for many years to come.
As far as motors go, KV is nothing more than rpm time voltage. So 1 volt equals 4600 RPM from a 4600KV motor. You need to have a dead minumum of 4000KV to have enough RPM on a 2S battery. If you where running 3S packs, like buggies use, you would want a much lower KV motor, since you are throwing another 3.7v into the mix to make up for the RPM loss.
Lower KV offers more torque, but at the cost of top end. You can gear a low KV motor up to get the top end, but you'll never beat a properly geared high KV system in the long haul down a straight. 4000 - 4700 is where you want to be with SCTs.

For batteries, you will generally want no less than 7200mah packs. Not really needing higher than 8000.
What is more important for the systems sake is the C rating. The amount of current that is can flow. The more the better. The more current a pack can throw, the less (IR) internal resistance will effect it. This means less heat and strain on your ESC and battery it's self. When you see a puffed pack, 9 times outa 10, it is because someone tried to get more current from a pack than it could produce, by running it with to high a KV motor that was asking to much from it.
I don't run anything less that 100C packs on my stuff, because I run a 4700KV hobbywing XERUN motor, and it likes the juice! You shouldn't either with that 4600!
You could get away with a 75C pack on a moderately geared 4000KV, because it doesn't need as much demand from the pack to get up and moving due to a more efficient low end torque band. Initial acceleration is generally where a battery is strained. This is where a higher burst rating on a pack comes in to play. For example, if a pack says 100C, that is only it's nominal flow rating. It might have a 150C burst capability, but it cannot feed that much in a constant scenario.
Timing is just like advancing a cars ignition. It will run quicker the higher the timing, but will suffer in the low RPM range, putting unnecessary strain on your system when launching. Generally you don't want to do to much with timing unless your running a low KV motor. I leave mine at 0 with my 4700. It doesn't need any more top end with a 16t pinion.

As for Cap packs, they are not needed on a more efficient system.
IE - The same equipment we are running on our SCT's on a smaller 1/10 scale vehicle for which this stuff was designed.

It is a really really ignorant rule by ROAR that prevents us SCT guys from running 3S systems in competition that we really should be running, because they consider SCT 1/10 scale. Never mind the fact it's the same size and close to the same weights as a 1/8 scale buggy... Idiots.
That being said, this is where the Cap packs come in.
When you are straining batteries by throwing large KV motors on heavy vehicle, only powered by a 2S 7.4v system, you are going to encounter lots of feed back/electronic noise.
This causes heat and internal resistance to spike in the battery/ESC. Even the motor.
By installing a low impedance capacitor pack inline with the battery input wires to the ESC, you are effectively providing a buffer that soaks up the ripple/noise and smooths out the power delivery.
Tekno Pro Jeremy McGuigan reported a 20 degree temp drop variance in his battery as well as significant reductions from his ESC and motor though out an 8 minute main with a cap pack installed on his RX8. Thats huge!
What you will want is the lowest impedance caps you can get. Those hobbywing caps I posted are the electrolytic type, (really low impedance) and are also protected by a little schottky diode, which can be looked at like a one way valve in regard to polarity induction. This means if you ever accidentally plugged a pack in backwards, it won't blow them up as it would without that diode. A lot of cap packs don't have those installed, so it's worth mentioning to you.

Josh L

iTrader: (1)

If you read in the last comment I replied to, you will have everything explained in more detail

But in short, not it's not the same as a glitch buster as far as where it goes.
However I run those as well, just to help the BEC out with my high voltage servos. Fundamentally it does the same thing in that respect.
You can't really go wrong having caps installed in both places.

This is the cap pack I recommend you get, until I get my caps in to start making my own systems.
HW cap pack

Here is a link from Castle Creations site that will explain where they go >
Cap pack Install instructions

szymanski2oo1

ah i see ... sorry didnt realise it was a link!
im running tekin rx8 and prohd motor in 5min heats and the batts do get warm... is it worth running a glitch buster on the receiver in addition?


It is a really really ignorant rule by ROAR that prevents us SCT guys from running 3S systems in competition that we really should be running, because they consider SCT 1/10 scale. Never mind the fact it's the same size and close to the same weights as a 1/8 scale buggy... Idiots.
That being said, this is where the Cap packs come in.
When you are straining batteries by throwing large KV motors on heavy vehicle, only powered by a 2S 7.4v system, you are going to encounter lots of feed back/electronic noise.
This causes heat and internal resistance to spike in the battery/ESC. Even the motor.
By installing a low impedance capacitor pack inline with the battery input wires to the ESC, you are effectively providing a buffer that soaks up the ripple/noise and smooths out the power delivery.
Tekno Pro Jeremy McGuigan reported a 20 degree temp drop variance in his battery as well as significant reductions from his ESC and motor though out an 8 minute main with a cap pack installed on his RX8. Thats huge!
What you will want is the lowest impedance caps you can get. Those hobbywing caps I posted are the electrolytic type, (really low impedance) and are also protected by a little schottky diode, which can be looked at like a one way valve in regard to polarity induction. This means if you ever accidentally plugged a pack in backwards, it won't blow them up as it would without that diode. A lot of cap packs don't have those installed, so it's worth mentioning to you.[/QUOTE]

szymanski2oo1

super thanks for the info!



[QUOTE=Josh L;14415528]If you read in the last comment I replied to, you will have everything explained in more detail

But in short, not it's not the same as a glitch buster as far as where it goes.
However I run those as well, just to help the BEC out with my high voltage servos. Fundamentally it does the same thing in that respect.
You can't really go wrong having caps installed in both places.

Josh L

iTrader: (1)

No problem!
These are things that aren't as widely realized by the majority.
As I stated, they wouldn't even be needed if the manufacturers would get their heads out of the sand. It would cost on penny more for ESC manufacturers to increase their on board capacitance, as would it make a lot more sense to have higher voltage capable BEC's that also have caps installed.
It's as if ESC companies are hoping some poor SCT guy runs it so they are forced to buy a cap pack from them with a ridiculous mark up on cheap Chinese parts, or better yet have to buy a new system because they fried the first one not knowing about these things...
But more to blame than the ESC makers are the rule writers of ROAR that cause unnecessary complications that cost us money.
Those people either don't care or must have fell out of the stupid tree and missed every common sense branch on the way down. That's how I feel about that.

szymanski2oo1

i dont suppose you have an idiots guide to setting the rear pills for antisquat and toe in etc..... i have a pile of pills here with me from the kit, the instructions for stock setup were clear, but im looking to change it a bit, im running on a very bumpy and unforgiving astro track and trying to get the truck to be a little more stable over the bumps..... now ive seen a few diagrams but they make no sense to me.... looking for a laymans instruction on what pils in which block do what!
any help appreciated!

rregl0612

iTrader: (33)

Just put a 410.3 on layaway, and just wanted to thank the above for info shared. That was the best read I've had in a few days

King DORK

iTrader: (53)

Dude knows his stuff for sure