6s vs. 4s?
 

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 :neutral:

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.

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:gasp: 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?

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.

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.

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??

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.

It was at the Neu web site :oops: 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:whistle:

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?

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

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.

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

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..

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!

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.

It's always so nice when someone comes along and clears up the fog in front of me, thanks. Now if you will explain to me the formula that you used to know that a 5000 mah 4s runtime is 15min. I already own a bunch of Enerlands that make up 2 sets of 4s and 1 set of 6s and they're 6000mah and using you formula they will be just 400mah under so they'll do just fine and should give me the same run time as my TP 8000mah 4s. I tend to stay away from 6s due to my share of fried MM ESC's but I cured that problem with xtra caps so I'll probably run a couple of laps with 6s just to see what it does but plan to run 1800kv 5s 47/12 setup on my 8 2.0

Thanks jsr, excellent information. Helps to put it in perspective.

The 15min runtime was just a number to make the math simple. Whatever runtime you get on your specific setup (which includes your motor, battery (capacity and discharge), vehicle weight, track size and design, and driving style) on 4s, if you want to keep that same runtime, then use the calculation I did in the previous post to find out what capacity you need in a 5s or 6s battery to make the same runtime.
Good luck and have fun!

Just curious because I'm looking at getting batts for a 5s/1800kv setup, what runtime are you getting with the 4s/2000kv setup?

Ok....I'm puzzled guys. I got my MBX6 buggy done. Running 6S 4400mah batt, motor is a 1512 1380KV motor. Running 15T pinion on it and after a 5min heat I'm using 1100-1200mah. WTF??? That puts me almost the same usage and runtime as a 4S 5000mah batt. I figured the 4S being only 74 w/h and the 6S being 97 w/h I would see pkenty of runtime. That calculates out to be only 16mins with a 6S 4400?? Doesn't add up. The buggy weighs 30 grams lighter now then it did with the 4S MMM 2200KV setup.

Is that geared for the same speed or more/less?

I think part of the issue here will be that you can get the same runtime with a lower kv motor + higher voltage and lower mah lipo, but to see an increase in runtime you need to keep the same mah capacity & lower the current draw ( HV and lower kv again ). Having a lower mah will reduce weight but lessen the advantage you get from lower current draw = same overall runtime.

I figured the total capacity of the batts would be the determining factor. The 4S 5000mah only has 74amp/hours. The 6S 4400mah is 97 amp hours. I figured that is a larger "gas tank" per say. So it should give me more runtime. The speed is the same.

Hmm, good point. Buggered if I know then :lol:

I think you'd need an Eagletree hooked up top get some more meaningful numbers to crunch.

Trust me, its got me scratching my head. :lol:

So, let's recap:

- Old system: MM2200 (1515) 2200kv on 4s 5Ah. Total rpm=32560. Weight=X.

- New system: Neu 1512 1380kv on 6s 4.4Ah. Total rpm=30636. Weight=X-30g.

Can we assume both systems are geared for the same approximate speed?

Otherwise, the only thing that stands out to me is the new system has a smaller motor pulling a taller gearing for not much difference in weight.

That is correct. Wondering now if I should have gone with a 1515 instead of the 1512. The gearing though did not change. I left the same pinion on, so speed might have dropped 1mph....but not much.

I too am looking for a viable 4s/20minute runtime setup. Seems like the best bet would be a Tekin 1700kv truggy motor to keep the amps down? On our medium sized track the CC 2200 gets just about 17-20 minutes but we need a reliable 20 minute main setup. Any input as far as the tekin motors go?

Are all the settings in the ESC and radio the same? Changing throttle curves, punch, etc will change runtimes.

Also are you driving the same? The buggy might be more controllable now in 6s so you're on throttle sooner/harder than with 4s thus consuming more average current.

there are other factors to runtime to consider. But if truly nothing chnaged then that's odd. But look at all variables first.

Gear the buggy up 2 teeth and see what happens to temps and runtime.

If you maintain the gearing you will need to have additional mah on the 5s setup as it will burn mAH just as fast as the 4s setup.. the point of higher voltage is not to increase speed, in fact you must gear down to see any benifits at all - temps, runtime etc. only show if you keep the speed the same as the other setup.

Also keep in mind going to a 6s setup you pretty much rule yourself out of any 'large event' only local club level play will allow this. With that said the only way you will feel any difference as far as performance goes "smoothness or torque power" is if you have batteries or an ESC that cant handle the amp load your throwing at it on the lower voltage setup. You may shave a couple degree's off as well w/ higher voltage but with a MMM combo or tekin combo you'll never have heat issues anyway.. I even ran a Medusa 60mm 2000kv on 4s as my primary motor for a full season of racing with ZERO issues. I currently run a 1y combo geared at 13t or less (depending on track size) and use Hyperion lipo's; 5k and 5.5k packs. I also use to run a 5s 1700kv (2.5d) setup in my 8ight truggy and have since swapped back down to a 1y combo, and I run 6500mAH hyperions in this setup and I have a 9000mAH pack for 30+ minute amains. Again no issues running at all.. with both systems running the 1y it makes it easy for me to swap out motors ecs's w/o any hassle if I do run into issues (havn't yet, knock on wood).

All the settings have remained the same. I did swap though from a MMM to a RX8, but I set the RX8 the same with zero timing, low punch and current limiter on full to limit any amp spikes. The driving hasn't changed as my lap times are still the same.

Ok guys, ran again this weekend on a tight track with lots of accel and decel. Used 1680mah per 5 min heat. That was the same setup once again, RX8, 1380 KV NEU 1512 motor. Same gearing...

Did end up with the same results though....TQ and win. Only thing good about it...lol

Swapped to a 1515 2Y and RX8 and going to see how that works out. Its lower rpm so I had to gear according to get the same mph. I will let you guys know what I find.

Still used virtually identical MAH per 5min heat. I am wondering if the battery itself simply can not keep up with the task. I am going to try a better battery with 25C discharge and see what happens. The setup is still not good enough for 20 mins.