c rating for a 4s setup in flux ? - RC-Monster Forums

speedy · **c rating for a 4s setup in flux ? -** 11.10.2009, 01:41 PM

Would 2x turnegy 20c 5000mah lipos be good enough in a 4s setup for the savage flux ?

Unsullied_Spy · 11.10.2009, 02:40 PM

They would work, but ideally 25-30C would be better. My experience with the 20C Turnigys is that they overall very good packs for the money and I'm sure the 20C 5AH lipos will be fine in your flux but there is no headroom for amperage.

Finnster · 11.10.2009, 02:49 PM

Depends on the motor. I run 2200s on mine and its fine. I have a 2200kv motor tho...

speedy · 11.10.2009, 02:53 PM

ok !

I'm going to run my flux with the stock motor and gear it for 35-40mph,useing the stock tires !

BrianG · 11.10.2009, 04:09 PM

That gearing may be a little agressive for 4s 5Ah 20C cells. Just watch the battery temps and adjust gearing accordingly.

04:13 PM

Quote:

Originally Posted by BrianG

That gearing may be a little agressive for 4s 5Ah 20C cells. Just watch the battery temps and adjust gearing accordingly.

? If its the stock 20/44 gearing on 4S, it will do 35mph+ easily outa the box like mine does and i've had no heat issues. And yes, I would opt for 25C rating to be on the safe side, no such a thing as too high of a C rating, it won't hurt. Now too low of a C rating on the other hand.....

speedy · 11.10.2009, 04:17 PM

with stock gearing and 4s the cc-2200kv motor won't pull more than like 90Amps right ? if it pulls 120-130amps on 6s with that gearing ?

Gdot · 11.10.2009, 05:20 PM

I damaged 99 amp batteries setup with the flux all stock 2200kv on 4s. I don't think 100 amps is enough.. I have 150 amp and up batteries for them now, and it's perfect. No warm batteries or anything of the sort.

BrianG · 11.10.2009, 05:53 PM

I think it also matters greatly how the vehicle is driven. If you are constantly doing heavy standing starts, it is going to push the batteries more (very frequent very high current bursts) than if you keep a relatively constant throttle level. Taming the ESC by dialing in some punch control helps to limit the current on heavy accelerations, but some people feel that this makes the truck feel more unresponsive.

fastbaja5b · 11.10.2009, 11:38 PM

Stock gearing, stock tyres, 4s lipo a standard launch is 120ish amps

I tested a pair of freshly charged Reedy 5000mah 20C packs and they dropped below 3v/cell on take off, that told me the battery wasn't up to the task.

Conclusion?

5000mah 20C is insufficient for the Savage Flux.

Gdot · 11.11.2009, 12:00 AM

didn't you get a data logger sheet for that? or who was the guy with the data sheets on the flux? That was a bit freaky on that sheet...

fastbaja5b · 11.11.2009, 01:51 AM

I've posted a few Eagletree graphs from my Savage on here.

lincpimp · 11.11.2009, 02:36 AM

Quote:

Originally Posted by fastbaja5b

Stock gearing, stock tyres, 4s lipo a standard launch is 120ish amps

I tested a pair of freshly charged Reedy 5000mah 20C packs and they dropped below 3v/cell on take off, that told me the battery wasn't up to the task.

Conclusion?

5000mah 20C is insufficient for the Savage Flux.

Well, the conclusion is that reddy 5000 20c packs are not up to task... I ran some old 4900 20c trakpower packs on a 4s savage 25 that I converted and they were OK, but they did get hot. 4s in a MT is a poor idea anyways, but you need good packs if you plan to do it.

Quote:

Originally Posted by Gdot

I damaged 99 amp batteries setup with the flux all stock 2200kv on 4s. I don't think 100 amps is enough.. I have 150 amp and up batteries for them now, and it's perfect. No warm batteries or anything of the sort.

150 amps for any 4s heavier setup (1/8 buggy and up) is a wise move. That will allow you to gear however you want and have headroom. If you want to use those 20c packs go with 6s 5k 20c and just gear it back down to 40mph or so (move volts and same overall speed equals less amps).

Quote:

Originally Posted by speedy

with stock gearing and 4s the cc-2200kv motor won't pull more than like 90Amps right ? if it pulls 120-130amps on 6s with that gearing ?

You cannot lower the voltage and expect the amps to go downs as well... Yes, a 6s setup will go faster than the 4s setup will with the same overall gearing, and yes it will draw a bit more due to the addl wind resistance and drag associated with higher speeds. But you can pretty much consider the amp draw will be about the same with the 4s and 6s setups.

Consider 120amps at 4s lipo is about 1800 watts. And say that 1800 watts gets you 40mph. Now add half as much voltage again (up to 6s) and you get 2700 watts. If you maintain the gearing you should get half as much speed again as well, 60mph. Now in the real world you will find the 6s setup can maintain voltage better under load, and that is about negated by the addl wind drag and other resistance from going 20mph faster. So it is a wash, the addl power gained by going to higher voltage is cancelled out by the need for more power to achive higher speed.

You need good lipos to run 4s in a heavy vehicle and really be able to push it. That is why all of these "crap" batteries are failing in 4s setups. Seeing all of these early life cycle failures from smc and the other "name brands" are not surprising to me. Overrate a pack, and a 4s MT with an aggressive driver will show you the real limits of the pack.

For this reason I went up to 6s in my trucks, and gear for mid 40s. I se no reason to not do this with the flux, as you can get inexpensive 3s packs that will fit the batt boxes, and tossing on a smaller pinion costs about 15 bucks.

Just my 2 cents, but they cost me thousands in lipos to come up with...

speedy · 11.11.2009, 04:42 AM

ok !

6s setups seems to be the best alternative then

But whats the dimetions of the batteryboxes ? Way can't you guy's please tell me this ?