20c 4s lipo or 30c 3s lipo??

[T-Bro]

Which will give your car more power? The extra cell with less a lower discharge rate, or the extra 10c? Both packs are 4100 mah.

[suicideneil]

More power doesnt always mean more speed. You need a certain voltage with a certain vehicle to be reliable and run cool, and attain a certain speed- a high C & mah battery will still be discharged rather quickly if you try to gear it too high (match the kv of the motor to the voltage you plan to run, then find suitable batteries for the amount of power you will need with that combo).

What vehicle?
What motor & kv?
What purpose/ intention?

[zeropointbug]

Yes, tell us what u want to run it in, then we can help make a decision.

[T-Bro]

I have 2 motors that I'm toying with trying to get the best setup for top speeds/drag racing.
Tc3 Buggy or a tc3 wich is 1 lb lighter
Medusa 50mm 4400kv/NEU 6700kv
MGM 160amp esc 16cell/5s lipo
NEU 3s 30c 4100mah/maxamps 4s 20c 4000mah

With the Medusa I had it geared at 78/25 and it ran pretty good with the 3s until the endbell came off during a crash. It's getting repaired now. Clocked at 48 mph
The Neu, I have geared at 78/20 and it runs ok but still gets kind of hot. Haven't clocked this setup yet... but I will today.
I have a feeling after a lot of reading that if I got a lower kv motor 2000kv possibly and ran a good 5 or 6s pack I'd run much cooler and probably get higher top speeds??

[suicideneil]

Low kv & high voltage is always the best way to achieve better temps, and with a speed run machine, you could spin the motors somewhat faster than the usual 30-40k, more like upto 50-55k or so (one of the Castle guys, Joe I think, ran his 2650kv motor on 6s lipo in his TC to get about 90-100mph).

Since this isnt an MT though, I wont be much further use- sounds though like the neu was spinning rather abit faster than it liked for it to get hot. I wouldnt run less than 4s though for speed runs, lots of current being pulled during acceleration so a higher C rating would be best to spare the batts and esc.

[lincpimp]

Your ,maxamps pack is good for about 60 amps, or 900 watts.

The neu pack should handle 120 amps, or 1400 watts.

I would go with the neu pack and the neu motor, but it is spinning a bit fast at 80k rpms. Good for a couple of speed runs, but not good to use till the pack dumps. The medusa on 3s will run cooler if you plan to play with it, but will not be as fast or powerful.

[T-Bro]

I wouldnt run less than 4s though for speed runs

So it will run cooler with more cells? I thought that would make it run hotter?? I want to move up to a 4/5s pack but was just to nervous about frying another esc.

Good for a couple of speed runs, but not good to use till the pack dumps. The medusa on 3s will run cooler if you plan to play with it, but will not be as fast or powerful

That's what I learned. I can dump the pack with the Medusa and it's still pretty warm. The Neu I'm only planning on using in Drag races not playing for 15 minutes etc. Thanks.

You guys are really alot of help right now and I really appreciaite your assistance! One last question... My schulze u-force just got fried while using the Medusa and the Neu 3s pack. I think I might have fried it by over braking... which I just read about after the fact. Or could I have fried it because the pack was too much for it to handle. The esc sais 2/4s lipo but I think it's a 100amp esc. Since my pack is 120 amps does that mean I went over the esc's limit? I really need to know because I have 2 mgm 80 amp esc's and 1 160 amp esc and I don't want to fry those also with these 2 setups I have. I know I'm planning on getting one of those new 4s 40c thunderpower packs so I need to know if my esc's can handle these big lipo packs or if I need to upgrade to a bigger more powerful esc.

[T-Bro]

also here's a video of my tc3 buggy with the neu motor and neu lipo...

[magman]

Nice....you left the nitro in the dust! Wasn't really much of a race...by the time the other shifter into 2nd.. you were almost at the finish line

[T-Bro]

lol thanks and I didn't even give it full throttle until about 1/3 of the track was gone. He's moving up to the 3.3 so we'll see if that helps him... I think I'll still take him. We'll see!

[spartan805]

Originally Posted by suicideneil

More power doesnt always mean more speed. You need a certain voltage with a certain vehicle to be reliable and run cool, and attain a certain speed- a high C & mah battery will still be discharged rather quickly if you try to gear it too high (match the kv of the motor to the voltage you plan to run, then find suitable batteries for the amount of power you will need with that combo).

What vehicle?
What motor & kv?
What purpose/ intention?

With that being said..... what is recommended for a 2650kv/MMM combo with 13/46 gearing.. 3S or 4S... the 2650 gets hot with 4s and 16/46 gearing havent tried the 13/46 yet. MBX5R... RACING! Thanks

[suicideneil]

Well, according to my calculations (run for the hills!) 13/46 on 4s means you would be geared for 44mph, on 3s that would be 33mph.

4s & 16/46 = 54mph- not suprized thats running hot really.

For racing 35-40mph seems the most common speed to go for, depending on the nature of the track (lots of tight technical corners needs less speed & more acceleration, and viceversa sort of). I would say though that both 4s and 3s can be made to work in your vehicle with the right gearing, done by lots of people, just depends what works best for you and your track/ driving style.

16/46 & 3s lipo = 41mph, do able I reckon.

As always though, keep an eye temps and gear up or down as needed- if you can access the track to test the different gearing & voltage options, definately do so & record the results to see which is the right direction (testing testing testing, its the only way really, unless you're one of those guys who gets lucky with the perfect setup on the 1st attempt).

hot motor & cool esc/batts = under geared.
cool motor & hot esc/batts = over geared.
hot motor and hot esc/batts = way over geared.
warm everything = bingo.

Is the general rule of thumb.

I would also check your esc settings- set the start power to low or lowest, and the timing to medium. A little exponential on the throttle curve is always nice, and punch control to 60-70% maybe or higher (less punch = less heat buildup from stop/start throttle use). Forgive me if Im preaching to the choir though, I just assume all new guys are thick and treat them as such until I know otherwise

Good luck

[magman]

Originally Posted by T-Bro

lol thanks and I didn't even give it full throttle until about 1/3 of the track was gone. He's moving up to the 3.3 so we'll see if that helps him... I think I'll still take him. We'll see!

Even w/the 3.3 you should still beat him!

[T-Bro]

Ok... but you guys still never got to my most important question...

My schulze u-force just got fried while using the Medusa and the Neu 3s pack. I think I might have fried it by over braking... which I just read about after the fact. Or could I have fried it because the pack was too much for it to handle. The esc sais 2/4s lipo but I think it's a 100amp esc. Since my pack is 120 amps does that mean I went over the esc's limit? I really need to know because I have 2 mgm 80 amp esc's and 1 160 amp esc and I don't want to fry those also with these 2 setups I have. I know I'm planning on getting one of those new 4s 40c thunderpower packs so I need to know if my esc's can handle these big lipo packs or if I need to upgrade to a bigger more powerful esc.

[suicideneil]

Missed that bit.

Schulze = fail, quite often, if you look at them wrong. (some people have more luck than others...).

Your lipos can put out 120amps continuous (in theory), but its the peak current draw that would kill the sculze usually, or going from forwards-brake/ standstill to forwards again is a known killer.

Your Tc3 shouldnt be putting too much strain on the esc, but, dpends on alot of things- they still programmed with the little dip switch things? I would check those out carefully to make sure nothing got upset.

Your 80amp MGms wouldnt be ideal, not without extra caps and a cooling fan or two (the MM is ~100amps and works for 1:8 scale stuff with the afforementioned mods), but the 160amp esc should be fine- MGM again? Just toning down things like start power and punch can have a posistive effect, and making sure the timing is set correctly for the type of motor- some escs are alot more sensitive to that kinda thing than others.