4 or 5lipos ?
 

Hi !

I have an ass rc8e ands a cc-mmm 2200kv combo that i'm going to race with :O) but i don't know if i chould use 4 or 5s lipo's ? What do you guy's think ?

Either will work, but for a given speed, 5s will be gentler on the batteries and runtime will be longer. So, whatever speed you gear for on 4s, gear down for 5s to get the same speed.

i use both, if i have to make a little longer race i throw a 5s pack in there, since there is more total energy in the pack

I prefer to race with 5s liking the speed and power that I get from 5s.

use the calculator on BrianG's signature to see what speeds you will get with either battery and what gearing you'll need to run for that speed. Sometimes the higher voltage won't let you gear down enough for usable speeds on the race track.

No, no, no, don't go 5s. There are a few good reasons why 4s is better in your situation. For one, the amount of power available is way, way to much for any type of track. You don't want something that is comfortable for 50-60 mph when you are spending most of the time going less than 30 mph. With the low throttle that you will be using most of the time, you will be heating up the esc a lot. Even if you geared way down, the motor will be spinning for nothing, and eat up your packs in a hurry. Reason 3 is the fact that 5s is taller than 4s. You want the lowest center of gravity for the best handling.

4s would be better for racing. Just get some good batts, like 30C and 5500mah or more of capacity and you should be good.

i just got done running at a huge track today running 4-5s, 4s on the tekin 2250 truggy motor is about 40 mph with the epa all the way up, speedo 140 motor 140 after 5 min quallifiers, put in a 5s and turned the epa down to 90 from 125 for 5s, after 15 mins, speedo 150, motor 150, i do not believe that turning the epa down affects the temp that much:whistle: is this agreed by my temps?

i dont race.... i bash, but my friends that race all prefer 4s

I forgot to say that i race on a grasstrack !!! Does that change anything ?
Grass pull more amp's right ? and what about 15/46 gearing ?

i want to chime in here. I have an 8ight-t 1.0 converted to Electric using CC Monster Mamba 2200kv combo and i have both 4s and 5s. 4s is way better on the track. Its the only time i run the car is on the track. Im getting 25mins outta my 4s 5000mAh 20c/25c packs. I get about the same on the 5s. 4s +++++ 5s is way hot, but runnable. 48t/15t gearing with the 4s packs no prbs

4s is more than necessary.

5s, maybe for a big track with higher speeds and longer straights.

Turning down the EPA is non-sense. Set the car up right. Turning down the EPA is limit the ESC and thus making it always have to work hard to know the motor timing and when to send power. Where as, when you have the ability, the ESc is now capable of working less, or "thinking" less and should therefore run cooler.

I still think that 5s geared down a little would be a better choice for bashing, especially on a grass track. And if he wants to gear up a little for some speed runs, it will be more than ready.

Couldn't agree more for bashing.

For racing, 4s is plenty and even sheds a little weight from the lighter 4s pack. Lighter= less strain.

But I also have to fall back on Steve Neu's recommendations of his motors being design to be most efficient in the 30-35K rpm range.

Yes, for racing, I agree; 4s. But he did say he's racing on a grass track. :wink:

And 2s for training which is what I do for my son (6) - just change from series to parallel adapter

Aw hell, you got me BG. I concede. I skipped over that post.

:lol:

Did that make your day? :lol:

about ESC and EPA. so should the EPA be set to 120%? or 100%?

Of course! Brevity on a Monday is always welcome. :smile:

It should be set to whatever you have it at during ESC calibration.

I always set mine to the max and then calibrate the esc and radio.

I usually set my EPA to 100% during calibration, and then increase it to 105% for operation. This makes sure I get to WOT even if I get a little component value drift on the throttle pot.

ah ok, well i had mine set to 100% so ill try 105% see if i notice a diff, doesnt matter tho, more power then i can use, even with punch set to 40%

turning the epa down is nonsense huh? have you not read my post? all it is doing is limiting your motor speed when running higher voltages, my speedo ran no hotter when i turned it down from 125 to 90, shoot im gonna buy a 6s and leave my gearing the same with the epa at about 70, just to do it:yes:

I don't believe it's nonsense as partial throttle is hard on the ESC. There are reasons why they make different types of ESC's for cars, boats, planes/heli's.
You would be better off gearing down but the EPA is an option, just not the best option.

Higher voltage is always more efficient but you need to have the appropriate wind motor and gearing.
A 5S 4000mAh pack is equivalent to a 4S 5000mAh but the 5S system will run cooler with the appropriate setup
A 6S 3200mAh pack is equivalent to a 4S 5000mAh but the 6S system will run even cooler with the appropriate setup

I do not believe this is true.

The total energy in each of those packs are about the same there for yeah, its roughly true.

Thats OK, you don't have to believe me, just do the math

Granted 6S would actually = 3333.33mAh, but with the extra efficiency, 3200mAh will suffice.

Are you joking?

thats more like it. i was merely saying that the value he was giving isnt correct.

Ah, okay gotcha... he is right as well, you need less "total" energy when you increase pack voltage. Higher C batteries will also give more energy than a lower C batt, simply because the voltage is higher under load, less throttle pull = less mah pull from battery.