6s vs. 4s?

[georgec]

Recently there have been some guys from Kentucky and Georgia coming to race with us at our local track (great bunch of guys) and all of them have ran 6s with 1400kv motors. A couple of them let me drive their buggies (MBX6) and they did seem to be noticeably smother than my 4s/2000kv setup and their motors all ran 5 to 8 degrees cooler. They didn't seem to be any faster than my setup just smother. All this has made me second guess my setup. Could it be that running higher voltage with a lower kv motors is that much more efficient than lower voltage with higher kv motors??? The overall cost is about the same because the batteries they were running were only 3300mAh as opposed to my 5000mAh and getting the same run time. As for motors they all ran the Tekin 1400kv, witch I don't know much about other than the price isn't bad. The funny thing is all but one ran the MMM esc and only one ran the RX8 esc.
Any input on this

[nitrostarter]

Well the higher voltage and lower kv is a preferred setup. You can run lower mah packs like the 3300mah to get the weight lower. Power and acceleration should all be roughly the same for track usage.

I do know the Tekin motors aren't as notchy either.

You don't have to run the RX8 unless you want to take advantage of the sensored running. Sensored is pretty nice on slow take offs and corner speeds. I'm not totally convinced it will improve anything since the RX8 shifts to sensorless while the rpms increase.

[georgec]

Thanks, I'm trying to come up with ammo to present to the track owners witch have adopted the ROAR 4s rule, but I believe can be swayed if I can prove to them that the only advantage to 6s is efficiency! I'm also on the hunt for a lower kv motor, and so far I have looked at the Tekin 1400kv that is priced at around $150.00 and the CC 1600kv priced at well over $200.00 Last night I came across another motor that Castle is carrying it's their NEU/MR 036/060/1300V5 priced at $119.00 makes it the most affordable. But if I'm reading the #s correctly this motor is only 36mm x 60mm and that seems small for racing. Has anyone here had any experience with these?

I came across another motor that Castle is carrying it's their NEU/MR 036/060/1300V5

Did you find this on CC websight, or Neu? I saw them yesterday on Neu, and looked at CC and did not see them.
IMO the 60 should do fine for a buggy, but that's based on my bashing the 60-2000 in my E-revo with no problems. But if Neu is going to restock all the sizes, they should have a 70 and 80 series coming. You might even be able to find a Medusa 70 around somewhere.

[bdebde]

Luckily my track has no battery rules... I run 6s 2600 with MMM and Neu 1509 2.5y (1450kv) in my Ve8. It is cooler and more efficient than my old 4s buggy. Max on motor has been 140 after two back to back runs. Batteries just get barely warm, and the MMM fan never comes on (except at power up). My old 4s buggy would get 160 on motor after one run.

[jzemaxx]

Any of you guys able to make the 20-25mins races in pro level with no batt swaps??? 4S 5000 is done at 12-13mins max....so what has been your solutions??

[florianz]

when running a 6s setup, you have lower amps and higher voltage. as your motor is pulling lower amps, you can have a similar runtime with smaller batteries.

basically, the power is supposed to be the same, but the performance is different. 5 or 6s is kinda smoother. I just love the torque of my 1700/1600kv four-pole motos.

as you're having a high voltage setup, the equipment is running cooler. further, it's easier for the batteries. for 4s setup you need higher quality batteries/higher c rating. like that, 5 or 6s is a bit cheaper, in general you don't need a 30c pack for that.

I've been running a xcelorin 1700kv on 5s for a long time, and now running a medusa 3680-1600kv on 5s. My 20c Turinigy 5s-Lipos never get too warm, power is more then sufficient, and I would never go for 4 s.

[georgec]

It was at the Neu web site long day. The track owner posted a message today stating that if no one in the 1/8th E class objected that it was fine with him to run 6s. I posted a poll and none of the other guys objected, so there goes another 300 bucks

[cornolio]

I've been running 4s setups for about 2 years.I've never had any power,heat problems.all my esc,motors batts still doing fine.should I switch to a 6s setup?

[Semi Pro]

im running 6cell 2600mah with a 1400kv teken setup on my 8ight and i love it

[georgec]

Yea I'm going the Tekin 1400kv route, everyone I spoke with said that Tekin has worked all the demons out of their motors and if their is a problem they will take care of it.

[georgec]

Originally Posted by cornolio

I've been running 4s setups for about 2 years.I've never had any power,heat problems.all my esc,motors batts still doing fine.should I switch to a 6s setup?

It's really just a personal preference, I find that the 6s 1400kv setup is much smother than my 4s 2000/2200kv setups and the higher voltage/lower kv setups constantly run cooler. And it would stand to reason that a motor and battery that is ran cooler will last longer, IMHO

[lincpimp]

If you go from 4s to 5s, maintain the same overall gearing and run the motors at the same speed the difference is quite noticeable. 6s makes a world of difference.

I have run some heavy vehicles on 4s, and then gone to 8s setups, with half the motor kv, half the amp rated escs and crap batteries wired in series. Even then the difference was noticeable, and my 8s setup cost about half what the 4s setup did (or less). If only we had an available 60 amp 8-10s car esc from castle, I would never run anything lower than 8s..

[kingdomracer]

Right now I have Thunder Power 22c 8000mah 2x2s=4s w/1800kv MMM combo. I get close to 25-30 min. no prob but would like to run more efficient and save some weight w/5s, how do I get the same runtime from lower mah batts. Is there a formula that will calculate the needed size batts? Plus can someone help me understand how is it that with a lower mah which leads to a lower constant for most batts out there (usually right around a 100 amps constant) is a good thing? I've been lead to believe that if my MMM is rated at 120 then I should make sure my batts are at the lowest 150, I don't see that same rule applying in a 3300mah batt with a much lower constant amp rating. I thought when you buy a lipo it should be based on 80% of the motor rated amp draw. I hope I made sense and I will not take any offense If I'm confused in my thinking. Plus it would help for the guys who are running the 5s and 6s 1600kv-1800kv setups to post their runtimes. Thankz!

[jsr]

Instead of thinking of how much mA your setup consumes per time period, think about Watts. So instead of looking at mAh, think Wh and do your calculation that way. Here's an example:

5000mAh 4s pack gets you 15min runtime
5A * 14.8V = 74Wh
This means you're consuming about 74Wh (not really as the LVC cuts it off before that) in approx. 15min.

Now, to get the equivalent runtime with a 6s setup, you want the same Wh capacity:
74Wh / 22.2V = 3.3Ah = 3300mAh

So choosing a 3300mAh 6s pack will get you equivalent runtime as a 5000mAh 4s pack.

Theoretically, the lower kV setup provides more available torque, but because the lower kV motors have more internal resistance and build up rpms slower, the torque is applied a bit slower thus you don't feel that additional torque as quickly as the torque provided from the higher kV motor (which gives the smoother feel). Also, the higher kV motor should theoretically have more top end speed, but because all these motors are way overpowered for the vehicles they're run in, we're not using all the available torque and power from the motors and the difference on the top-end is dampened so they how quickly they reach that top speed is not as noticeable.

Higher voltage is better for heat, however there are other items that wear a bit faster (such as the ESC caps as their life is shortened with higher voltage, but operating life should still far exceed your usefulness of the ESC). For me, I get 2000-2300kV motors for considerable lower price than the lower kV motors from Neu, Neu-Castle (their 1800kV motor is nice), and Tekin, so I'm sticking with 4s until the lower cost 4s motors are no longer available or lower cost 5s and 6s motors are available. Plus, my other RCs are set up to run on 4s also, so the compatibility is useful for me. Otherwise, I would run 5s or 6s.
For those concerned with the price of the Neu-Castle 1600kV, it's a monster sized motor that IMO is too big for buggies and truggies (you'd be using a small percentage of it's potential, which is why it runs so cool). The Neu-Castle 1800kV 1512 motor is a nice option that's similarly priced to Tekins and would run well on 5s (6s is a bit too fast and you'll lose most of that runtime advantage).

Oh, forgot about your battery question...
Don't go by the ESC amp ratings...they're all BS. They usually go by the rated FET capability at 25C instead of derating for operating temps or design limitations.
The higher voltage you go, the lower current capability you "need". I say "need" because most people get more than they "need" because the higher discharge packs have lower resistances (which is why they can discharge more current), so they feel punchier. There's a difference between "need" and "want". You don't "need" a 150A discharge capability pack, but you may "want" one. Also, higher discharge packs will run a bit cooler (again, due to the lower internal resistance). It's up to you.