6s vs. 4s?

[kingdomracer]

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

[georgec]

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

[jsr]

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!

[kingdomracer]

Originally Posted by 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

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

[jzemaxx]

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.

[suicideneil]

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.

[jzemaxx]

Originally Posted by suicideneil

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.

[suicideneil]

Hmm, good point. Buggered if I know then

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

[jzemaxx]

Originally Posted by suicideneil

Hmm, good point. Buggered if I know then

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.

[BrianG]

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.

[jzemaxx]

Originally Posted by BrianG

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.

[DCastaneda]

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?

[jsr]

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.

[lincpimp]

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

[stum]

Originally Posted by 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..

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).